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Error P1502 2000 Boxster S


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I've searched and seen several older posts on this topic but no solution. I have a 2000 Boxster S. Replaced bad fuel pump, had to remove battery of course to do it. Hooked everything back up and I have a P1502 stored as a pending error code and car won't rev past 1200 rpm, scan indicates that elec throttle is not opening past 5.8% in fact it is not moving at all, just stuck at 5.8%. I can go through the throttle adaption procedure with no change whatsoever. If I clear the code I can hear the elec throttle begin to buzz immediately and car runs fine until it is shut down. Upon restart code is set again. Anyone ever come with a solution for this??

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I've searched and seen several older posts on this topic but no solution. I have a 2000 Boxster S. Replaced bad fuel pump, had to remove battery of course to do it. Hooked everything back up and I have a P1502 stored as a pending error code and car won't rev past 1200 rpm, scan indicates that elec throttle is not opening past 5.8% in fact it is not moving at all, just stuck at 5.8%. I can go through the throttle adaption procedure with no change whatsoever. If I clear the code I can hear the elec throttle begin to buzz immediately and car runs fine until it is shut down. Upon restart code is set again. Anyone ever come with a solution for this??

P1502 Throttle Jacking Unit, Spring Test – Above Limit

Clean the connectors, check the wiring for damage - clear the code and see if it comes back.

If it does, you will likely need a new throttle jacking unit.

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I've searched and seen several older posts on this topic but no solution. I have a 2000 Boxster S. Replaced bad fuel pump, had to remove battery of course to do it. Hooked everything back up and I have a P1502 stored as a pending error code and car won't rev past 1200 rpm, scan indicates that elec throttle is not opening past 5.8% in fact it is not moving at all, just stuck at 5.8%. I can go through the throttle adaption procedure with no change whatsoever. If I clear the code I can hear the elec throttle begin to buzz immediately and car runs fine until it is shut down. Upon restart code is set again. Anyone ever come with a solution for this??

P1502 Throttle Jacking Unit, Spring Test – Above Limit

Clean the connectors, check the wiring for damage - clear the code and see if it comes back.

If it does, you will likely need a new throttle jacking unit.

Thanks for the quick reply, I have seen other posts where this problem manifested itself solely due to disconnecting the battery or by having the battery become low. I have also read of several other's replacing the e-throttle assembly itself without success. Hopefully someone can chime in with an actual successful repair.

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I've searched and seen several older posts on this topic but no solution. I have a 2000 Boxster S. Replaced bad fuel pump, had to remove battery of course to do it. Hooked everything back up and I have a P1502 stored as a pending error code and car won't rev past 1200 rpm, scan indicates that elec throttle is not opening past 5.8% in fact it is not moving at all, just stuck at 5.8%. I can go through the throttle adaption procedure with no change whatsoever. If I clear the code I can hear the elec throttle begin to buzz immediately and car runs fine until it is shut down. Upon restart code is set again. Anyone ever come with a solution for this??

P1502 Throttle Jacking Unit, Spring Test – Above Limit

Clean the connectors, check the wiring for damage - clear the code and see if it comes back.

If it does, you will likely need a new throttle jacking unit.

Thanks for the quick reply, I have seen other posts where this problem manifested itself solely due to disconnecting the battery or by having the battery become low. I have also read of several other's replacing the e-throttle assembly itself without success. Hopefully someone can chime in with an actual successful repair.

Please do as I suggested.
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I've searched and seen several older posts on this topic but no solution. I have a 2000 Boxster S. Replaced bad fuel pump, had to remove battery of course to do it. Hooked everything back up and I have a P1502 stored as a pending error code and car won't rev past 1200 rpm, scan indicates that elec throttle is not opening past 5.8% in fact it is not moving at all, just stuck at 5.8%. I can go through the throttle adaption procedure with no change whatsoever. If I clear the code I can hear the elec throttle begin to buzz immediately and car runs fine until it is shut down. Upon restart code is set again. Anyone ever come with a solution for this??

Finally changing throttle valve helped we this issue, Boxster S 2000.

P1502, finally brought me to change the throttle valve unit. First tried the one of friends car (the same) and knew enough, problem was fianlly solved. After changing mass meter and all other electric things, it finally was the throttle valve.

good luck , Boris

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  • 7 months later...
I've searched and seen several older posts on this topic but no solution. I have a 2000 Boxster S. Replaced bad fuel pump, had to remove battery of course to do it. Hooked everything back up and I have a P1502 stored as a pending error code and car won't rev past 1200 rpm, scan indicates that elec throttle is not opening past 5.8% in fact it is not moving at all, just stuck at 5.8%. I can go through the throttle adaption procedure with no change whatsoever. If I clear the code I can hear the elec throttle begin to buzz immediately and car runs fine until it is shut down. Upon restart code is set again. Anyone ever come with a solution for this??

P1502 Throttle Jacking Unit, Spring Test – Above Limit

Clean the connectors, check the wiring for damage - clear the code and see if it comes back.

If it does, you will likely need a new throttle jacking unit.

Thanks for the quick reply, I have seen other posts where this problem manifested itself solely due to disconnecting the battery or by having the battery become low. I have also read of several other's replacing the e-throttle assembly itself without success. Hopefully someone can chime in with an actual successful repair.

This is getting frustrating. I'm having the exact same problem with a 2000 Boxster S. DTC P1502 is the only code present and the symptoms are identical. After performing the diagnosis and adaptation procedure outlined in the service manual, the throttle assembly was replaced (as instructed in the test procedures) with a new unit from Porsche and the adaptation procedure was done again. There was no change in the condition, and after following the test procedure again, it (again) pointed to the throttle assembly as being defective, since (apparently) there is no other possible cause...at least according to Porsche.

After doing a search of the web I've found well over a dozen instances of this happening. In all cases it seems to be related to the battery going dead or being disconnected for some reason. Some have replaced both the throttle assembly, as well as the air flow sensor - with no change. (I think I've only found one or two instances where the throttle assembly was actually defective and truly causing this problem.) There are no TSB's from Porsche addressing this issue, and no one ever seems to post the actual fix if (or when) they find it.

Does ANYONE know what's causing this issue? If so, what did you finally find it to be?

thanks,

Erick

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  • 2 years later...

Interested to spot this as I have exactly the same problem on my 2000 2.7 Boxster 986.

I've fitted a new throttle body and done the adaption procedure....but still get the same P1502 code.

If I clear the code with a Durametric it runs fine, if I disconnect the MAF sensor lead it runs fine, but if I reconnect the MAF and turn the ignition off/on I get the same problem.

I've thought about changing the MAF, but others posting on the web with a P1502 have done it and it made no difference, so I'm not convinced - also I get no MAF errors from the Durametric, just the P1502.

I thought it might be the DME - sent it away to be tested, but no errors found.

I also get no CEL light, just the P1502 from the Durametric?

If I disconnect the MAF lead I can hear what sounds like a high pitched motor from the engine bay (different from the sound the throttle body makes as the pedal is pushed) when I turn on the ignition, but I don't get that when the MAF sensor is connected?

Could it be failing another initialisation procedure before it even gets to try to initialise the throttle?

The Durametric shows that the pedal potentiometer is ok (plus it works fine when the code is cleared).

As has been said, the fault is mentioned a fair bit on the web but nobody has listed the fix (other than a few posts which said fitting a new DME fixed it or leaving the DME 'out on the bench for a few days' and then re-fitting it fixed it (not sure why that would repair a faulty DME?)

If it happened intermittently after using the car I could accept that one of the chips on the board was failing when it got hot, but because it works fine when you clear the code I'm at a loss as to what it could be.

If one of the six lead to the throttle body connector was broken or shorting out, surely it would still not work after you had cleared the P1502 fault?

Any ideas?

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Ok - I've managed to fix it!

Here is what was NOT the cause of the problem:

- Throttle Body

- MAF sensor

- DME

- Wiring loom

(I had already changed the throttle body and had checked the wiring between the DME and throttle body connector)

Today I did the following:

a. Checked that the relays in the rear trunk (DME and Ignition) were seated ok - they seemed to be

b. Connected jump leads from another car to the Porsche battery - my battery has completely died a few times over the last year (the car is used fairly infrequently)

c. Turned the ignition key to position 2 (dashboard lights on) and then off about a dozen times (fairly quickly)

I did a. because I wondered whether the DME was being powered up correctly - there are a lot of posts on the web about poorly manufactured Porsche relays (which have a habit of failing).

I'm not convinced this solved the problem (I could hear the relay clicking when the ignition key was turned on), but I'll probably change the relays as they're cheap to buy and it will be useful to have a spare one in the car.

I did b. because I wondered whether the battery might be 'on the way out' - I was concerned that the battery voltage might be low and that this could cause the DME a problem.

I checked the voltage across the Porsche battery with a multimeter (about 12.2 V) - not significantly low, but the battery in the other car was 12.8V.

Again, I'm not convinced this solved the problem - I still couldn't hear the throttle body motor when I turned the ignition key on.

I then tried c. and on about the 12th time I left the ignition key in Position 2 (on) - this time I could hear the throttle body motor running!

Definitely a good sign, so I turned the key further to start the car...full revs, no limp mode, no poor idle, no flat spots...Christmas had come f'kin early!!!

With the engine running I used the Durametric to clear the codes.

I then turned the engine off and started it again...all still ok....did this a couple more times to check....problem solved.

Later I ran another Durametric test - no dreaded P1502, everything ok.

I have no idea why the 'ignition cycling' fixed it - could it be a faulty battery (will fit a new one tomorrow), or relay (will replace it when I get a chance) or ignition key barrel (unlikely) or perhaps the DME was in some 'fault state' and the power on/off corrected it (unlikely as I had previously disconnected it for a day which would have reset the DME)?

However, I know that Porsche Guildford wanted to start by fitting a new throttle body (£1500 just for the part - identical to a new Bosch one that I bought online for £370), would probably have then recommended fitting a new MAF sensor (£600 just for the part - identical to new Bosch one at a local motor factors for £200), and might then have recommended fitting a new DME (god knows how much that would have cost from Porsche....).

I'm guessing that I didn't need to buy the throttle body (or pay £70 to get the DME tested), but who cares - I'm still on a high from getting the car working again!

(Actually, the engine is responding brilliantly, so perhaps a new and clean throttle body did make a difference)

I also purchased a Durametric tester - well worth the money as I wouldn't have known it was a P1502 fault otherwise.

I hope the above helps someone else....and saves them 2 frustrating weeks trying to work out what it could be!

Regards,

Nick.

Edited by Nick2508
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Actually, I've since seen a lot of posts on the web about the electrical portion of the ignition key switch.

It's another cheap and easy part to change, so may do that as well after I've fitted new DME and Ignition relays.

I'll post an update if I get any further info after changing/inspecting the relays and switch...

Edited by Nick2508
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Yup nobody knows what's causing this or what the cure is,,,,,every time your battery goes low or replace one, you need a new throttle assembly? Yeah right!

One thing I notiiced is this only happens to MY 2000. A few solved it by cycling the key hundred times,keeping your DME on the bench and reconnecting it,,,I wish I can get lucky like that.

Now I don't even get that P1502 code anymore but my air bag light is ON. Maybe it has something to do with the alarm box under the seat.

Scanned a few things while she is running,,,throttle stuck at 5% rpm does go over a bit over 2000 scanner still reads 5%. Interesting thing is, intake temp was reading 90degrees when my garage was not even 60 degrees???

Gotta ask this to nick,,, after your 12th time when u heard the motor buzz how long was that motor on for?

Any possibility it was just the bad ignition switch perhaps u kinda fixed the tumbler while cycling it.

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It was a 'high pitched hum' - which went away when I pressed the throttle pedal (I could then hear the butterfly valve moving).

A bit confusing, as presumably the motor in the throttle body only turns when the pedal is pressed?

I had the engine cover off at the time - when it was replaced you couldn't hear it (unless you opened the door and listened carefully)...so, not a problem.

Once the problem was fixed I could hear the throttle body 'initialize' when I turned the ignition on and waited 1 minute (without touching the pedal) - hadn't heard that before.

I'm starting to think that it was the electrical portion of the ignition key switch - agreed, perhaps the internal tumbler/contacts had become misaligned and the 'ignition cycling' moved them back into the correct position.

I've only just got back from holiday so haven't had a chance to swap out the relays or switch - I'll open them up after I change them and let you know if I see any possible fault/cause.

I also wondered about the alarm box under the seat - but the carpet was bone dry and so I didn't bother to take the seat out and check it further (other than pushing the electrical connectors to make sure they were plugged in ok - they were).

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Yes, she has woken up!

Don't waste your time Nick,,,at least in my case it Was none of the above.

No durametric this point so waited til heard the throttle body engage for about 2seconds, left the key for a minute, off for 10 seconds,disconnected -battery cable for 2days,first try today all gravy.

My 2cents on this,,, once you lose your throttle adaption, is very tricky to get it reprogrammed again.

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Good news!

It's a mystery what causes it - perhaps the DME gets into an inconsistent state, that the 'ignition cycling' or 'leaving the DME on the bench for a day' sorts out?

Disconnecting the battery for 2 days would have cleared the DME fault codes - have you managed to 'lose' the air bag fault light?

Perhaps the problem was fixed before you did the adaption (did you try the 'ignition cycling'?) but you needed to clear the fault code (by removing the battery) for it to be saved by the DME.

Who knows, but we'll quit while we're ahead....:o)

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  • 1 year later...
  • Admin

Sorry for resurrecting an old thread but my 2000 boxster is also having this problem. Did any of you solve this problem?

Thanks!

P1502 Throttle Jacking Unit, Spring Test – Above Limit

Clean the connectors, check the wiring for damage - clear the code and see if it comes back.

If it does, you will likely need a new throttle jacking unit.

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  • 3 months later...

It's 18 months since I had the 'throttle body limp mode' problem and it hasn't happened since.

As mentioned, I changed the DME relays and ignition switch shortly afterwards - I don't think there was a problem with the relays, but they were inexpensive and I now have a couple of spares.

I think the cause of the problem was the ignition switch - when I changed it I had a look at the old one, it seemed to be slightly worn and there was a bit of play in the mechanism. Inside there are a lot (about 8 if I remember correctly) of contacts and a couple looked slightly pitted and had traces of carbon on them - perhaps the tumblers had come out of alignment?

If you have a similar problem, I would try turning the ignition on and off a dozen times in quick succession to see if that fixes it, before bothering to buy a new throttle body, MAF sensor, DME, etc.

No guarantees, but worth trying as it won't cost you a penny....!

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  • 2 months later...
I reopened this thread to add my experience and outcome. Like many, the P1509 fault occurred after disconnecting the battery for other work. I went through the same t-shooting steps i.e., disconnected the MAF, removed and cleaned the throttle body, performed the throttle adaptation adjustment, removed the DME for 24 hours, etc.


I found in another thread if disconnecting the MAF took it out of limp mode, then the MAF was bad. With that advice I purchased another MAF only to find the fault continued. Like many, I was able to get it out of limp mode by clearing the code with my code reader while the car was running. Only to have the code return during the next start.


I finally made the decision to purchase the throttle body. Afterall as Loren continues to point out in this thread: Clean the connectors, check the wiring for damage - clear the code and see if it comes back. If it does, you will likely need a new throttle jacking unit.


When I received the new throttle body, I compared it with the old unit. I could tell immediately the butterfly valve was slower to return on the old unit. That seems to fit the descripton of the code: Throttle Jacking Unit, Spring Test – Above Limit.


I installed the new throttle body and first performed the adaptation calibration. With the old unit, I could hear the butterfly valve open and close once immediately after turning on the ignition. I'm certain that is to test the throttle response. With the new unit, I could here the valve cycle immediately, and then 30 - 40 seconds in to the adaptation calibration. I suspect after the DME received the delayed pulse from the old unit, it immediately generated the P1509 code.


After replacement of the throttle body, the car (roughly at 100k miles) has run flawlessly. In fact, the throttle response has slightly improved. One question I do have for all this misery: Why did Porsche program the DME to basically shut down the car for the P1502 condition? I can understand generating a check engine condition, but to render the car basically useless seems a bit overkill; and can ruin your day if you are driving it miles from home.

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  • Moderators
I reopened this thread to add my experience and outcome. Like many, the P1509 fault occurred after disconnecting the battery for other work. I went through the same t-shooting steps i.e., disconnected the MAF, removed and cleaned the throttle body, performed the throttle adaptation adjustment, removed the DME for 24 hours, etc.
I found in another thread if disconnecting the MAF took it out of limp mode, then the MAF was bad. With that advice I purchased another MAF only to find the fault continued. Like many, I was able to get it out of limp mode by clearing the code with my code reader while the car was running. Only to have the code return during the next start.
I finally made the decision to purchase the throttle body. Afterall as Loren continues to point out in this thread: Clean the connectors, check the wiring for damage - clear the code and see if it comes back. If it does, you will likely need a new throttle jacking unit.
When I received the new throttle body, I compared it with the old unit. I could tell immediately the butterfly valve was slower to return on the old unit. That seems to fit the descripton of the code: Throttle Jacking Unit, Spring Test – Above Limit.
I installed the new throttle body and first performed the adaptation calibration. With the old unit, I could hear the butterfly valve open and close once immediately after turning on the ignition. I'm certain that is to test the throttle response. With the new unit, I could here the valve cycle immediately, and then 30 - 40 seconds in to the adaptation calibration. I suspect after the DME received the delayed pulse from the old unit, it immediately generated the P1509 code.
After replacement of the throttle body, the car (roughly at 100k miles) has run flawlessly. In fact, the throttle response has slightly improved. One question I do have for all this misery: Why did Porsche program the DME to basically shut down the car for the P1502 condition? I can understand generating a check engine condition, but to render the car basically useless seems a bit overkill; and can ruin your day if you are driving it miles from home.

Like all OEM's, Porsche has selected several faults that can trigger "limp mode", most of which related to either what they consider safety issue or severe emission related problems that could result in damage to the vehicle.

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  • 1 year later...

Ok - I've managed to fix it! Here is what was NOT the cause of the problem: - Throttle Body - MAF sensor - DME - Wiring loom (I had already changed the throttle body and had checked the wiring between the DME and throttle body connector) Today I did the following: a. Checked that the relays in the rear trunk (DME and Ignition) were seated ok - they seemed to be b. Connected jump leads from another car to the Porsche battery - my battery has completely died a few times over the last year (the car is used fairly infrequently) c. Turned the ignition key to position 2 (dashboard lights on) and then off about a dozen times (fairly quickly) I did a. because I wondered whether the DME was being powered up correctly - there are a lot of posts on the web about poorly manufactured Porsche relays (which have a habit of failing). I'm not convinced this solved the problem (I could hear the relay clicking when the ignition key was turned on), but I'll probably change the relays as they're cheap to buy and it will be useful to have a spare one in the car. I did b. because I wondered whether the battery might be 'on the way out' - I was concerned that the battery voltage might be low and that this could cause the DME a problem. I checked the voltage across the Porsche battery with a multimeter (about 12.2 V) - not significantly low, but the battery in the other car was 12.8V. Again, I'm not convinced this solved the problem - I still couldn't hear the throttle body motor when I turned the ignition key on. I then tried c. and on about the 12th time I left the ignition key in Position 2 (on) - this time I could hear the throttle body motor running! Definitely a good sign, so I turned the key further to start the car...full revs, no limp mode, no poor idle, no flat spots...Christmas had come f'kin early!!! With the engine running I used the Durametric to clear the codes. I then turned the engine off and started it again...all still ok....did this a couple more times to check....problem solved. Later I ran another Durametric test - no dreaded P1502, everything ok. I have no idea why the 'ignition cycling' fixed it - could it be a faulty battery (will fit a new one tomorrow), or relay (will replace it when I get a chance) or ignition key barrel (unlikely) or perhaps the DME was in some 'fault state' and the power on/off corrected it (unlikely as I had previously disconnected it for a day which would have reset the DME)? However, I know that Porsche Guildford wanted to start by fitting a new throttle body (£1500 just for the part - identical to a new Bosch one that I bought online for £370), would probably have then recommended fitting a new MAF sensor (£600 just for the part - identical to new Bosch one at a local motor factors for £200), and might then have recommended fitting a new DME (god knows how much that would have cost from Porsche....). I'm guessing that I didn't need to buy the throttle body (or pay £70 to get the DME tested), but who cares - I'm still on a high from getting the car working again! (Actually, the engine is responding brilliantly, so perhaps a new and clean throttle body did make a difference) I also purchased a Durametric tester - well worth the money as I wouldn't have known it was a P1502 fault otherwise. I hope the above helps someone else....and saves them 2 frustrating weeks trying to work out what it could be! Regards, Nick.

 

Hi Nick,

I had the same problem. Took it to Porsche, they swapped throttle body, etc and then they recommended I take the DME to a local repair center.

I had a look  inside the DME and saw one of two electrolytic capacitors leaking electrolyte. I asked the repair center to replace both caps,

(100uF 40V). They said they found two poor connections in the DME and replaced the caps, they tested the unit and claimed its ok.

I installed it, same problem. I then decided to do the ignition thing, by turning the ignition rapidly on and off for about 20 times. Then stared the car without waiting and was ok! I then turned off the ignition, waited a while, turned it back on, I could then hear the throttle body do its thing.

I think it could be a poor relay connection on start up? For now its ok, but I will check what relays are involved during start up.

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  • 1 year later...

Huge thanks Nick2508 for figuring this out.

Got this issue (limp mode = rough idle, max. rpm at 1900rpm, no power) yesterday with my Boxster S 2000 after having run out of fuel. Did not check error codes, but symptoms are exactly the same.

There are numerous threads, but this is the only one I found with the solution that works = switching ignition off and on fast for about 20 times.

I was getting prepared for a TB swap, ... and was really relieved to see this worked!

 

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  • 1 month later...

Brilliant and helpful but we do not understand why this rapid cycling of the switch works.

The 'new battery' fix works because the voltage was too low to activate the throttle 'jack' mechanism?

The cycling may work because it is  just cleaning the contacts in the ignition switch ?

Either way, a new Ignition switch and battery is a cheaper & simpler solution than the MAF+DME+TB+ list  given initially.

But after battery replacement, don't forget the Initialization Procedure ! And get your radio code ready before you disconnect.

Thanks for sharing

Edited by Schnell Gelb
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  • 1 year later...

Have been fighting the P1502 issue scince I jump started my Boxster S (-00) after winter storage. Car would run fine with MAF disconnected => got new battery and new MAF, same problem => cleaned throttle and position sensor - same problem => disconnected the ECU for a couple of days - same problem => cycled ingition on and off - MANY times - same problem!

What worked for me was - with the motor cover off, so you ca hear the throttle, turn the ignition on and off until you hear the throttle opening and closing within a second or two - thats when I got my computer to store the throttle settings! If you hear a buzz when you turn the key and a second one 15-30s later it wont work - the clicks have to be within 1-2s!

So "cycling" the ignition works but you have to hear the two clicks for the computer to store the settings correctly! (in my case at least)

Edited by RCDesign
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1 hour ago, RCDesign said:

Have been fighting the P1502 issue scince I jump started my Boxster S (-00) after winter storage. Car would run fine with MAF disconnected => got new battery and new MAF, same problem => cleaned throttle and position sensor - same problem => disconnected the ECU for a couple of days - same problem => cycled ingition on and off - MANY times - same problem!

What worked for me was - with the motor cover off, so you ca hear the throttle, turn the ignition on and off until you hear the throttle opening and closing within a second or two - thats when I got my computer to store the throttle settings! If you hear a buzz when you turn the key and a second one 15-30s later it wont work - the clicks have to be within 1-2s!

So "cycling" the ignition works but you have to hear the two clicks for the computer to store the settings correctly! (in my case at least)

 

P1502 is the code for a short circuit in the end stage fuel pump relay circuit.  Check the relay, if it is OK, check the wiring from the DME to the fuel pump relay for a short to B+.

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  • 1 year later...

I have the same problem with the P1502 code on my 2000 Boxster. My car is the base model, not the S.  Is the P1502 problem and the on/off ignition switch fix  limited to the S?

 

I had a bad ignition switch last year. I replaced the switch with a aftermarket part.   Could the ignition switch be a reason for the limp mode and 1502 code?

 

My car runs great once I clear the codes while the engine is running.   Once the engine is turned off, the limp mode returns and the P1502 code

 

I took my car to an independent garage yesterday.  They want $2500 to replace the throttle body.  They said that this could fix the problem or may just be the first step

 

I would really appreciate some help!!

 

Bob

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