Erratic Idle Code P1502

[RG Najarian]

Coincidence? Perhaps But Annoying as HELL!

I was trying out the latest software 6.0 from Durametric on my 2000 2.7 when all of a sudden it started Idling very erratically. VERY rough. I pulled the following code,

P1502:

Porsche fault code 412 - DVE fault during spring test exceeds limit value

When I reset the code the car levels out and runs normally.

However, when I shut off the motor and start it up again I get the same code and same erratic idle.

Any thoughts? Is this a DIY?

[Loren]

P1502 Throttle Jacking Unit, Spring Test – Above Limit

Fault area

– Throttle part

[RG Najarian]

Thanks Loren

This is looking like a Dealer/Mechanic type fix and not a DIY.

Weird coincidence it started after I hooked up the ODB II scanner.

[Loren]

If you can clean a throttle body then you can likely do this.

It comes down to whether the connector is bad or their is a damaged wire - if not you will need the throttle jacking sensor or a new throttle body.

[minny]

I am resurrecting this thread for some help and advice. After an oil change on a friend's car, it ran fine for a couple of days then the MIL lit. The car wouldn't rev and idled roughly. The PIWIS code was P1502. Connectors and wiring were checked and all was fine. The output from the DME to the throttle body reads 0-14v. With the car running and the code cleared, it runs fine until the the car is switched off and restarted then the MIL comes back on and the same code arises. We replaced the throttle body and air mass meter but there is no difference. The airmass meter reading is 17.5kg/hr at idle. The spanner in the works is that the car runs fine with the airmass meter disconnected.

[Loren]

I am resurrecting this thread for some help and advice. After an oil change on a friend's car, it ran fine for a couple of days then the MIL lit. The car wouldn't rev and idled roughly. The PIWIS code was P1502. Connectors and wiring were checked and all was fine. The output from the DME to the throttle body reads 0-14v. With the car running and the code cleared, it runs fine until the the car is switched off and restarted then the MIL comes back on and the same code arises. We replaced the throttle body and air mass meter but there is no difference. The airmass meter reading is 17.5kg/hr at idle. The spanner in the works is that the car runs fine with the airmass meter disconnected.

P1502 Throttle Jacking Unit, Spring Test – Above Limit

Possible casue:

- Throttle return time too long.

Try cleaning the throttle jacking unit and the throttle body well with carburetor or fuel injector cleaner.

If that does not clear the problem you will likely need to replace the throttle jacking unit.

[minny]

Thank you. I will give that a try. The throttle body was replaced after all the wiring and connector checks so that should not be the problem.

[minny]

Hi Loren, we replaced the throttle body and jacking unit but the light came back on so we replaced the units from a same model year identical car that was working fine but to no avail. There are 2 MAFs listed for MY 2000 boxster s so we tried both but there was no joy. Checked the wiring and connectors again but all seems well. Could it be a faulty DME. There are no other codes recorded.

[Loren]

If you want to use the newer style MAF the DME programming has to be updated for it to work right. Best to stick with the original part number until you get the first problem sorted.

The MAF has very little to do with idle - it is used at 4000 RPM and above to to adjust for air flow changes.

As I said clean the throttle body and inspect the throttle butterfly for damage or sticking.

[coleta]

Loren, that 4k rpm figure is an industry standard or is there a Porsche doc on it?

[Loren]

You can read the Porsche Service Information Book and/or the After Sales Training - Advanced Engine Management Systems book -- for information than you likely want to know... ;)

[minny]

An update on the above P1502 code. After replacing the throttle body and throttle jacking unit, the light still appeared. Connections were checked and the DME was finally replaced which solved the problem.

[wickedst]

Sorry for bringing this issue up from the past but any help would be greatly appreciated.  I have a 2002 boxster 986 w the e throttle also.  I have very similar issues as above.  I have replaced the throttle body assembly and the accelerator pedal potentiometer at the pedal assembly.  Both with now resolve.  My code is P1503 DVE fault position deviation which i believe is also the throttle body.   Your post is the only one which says replace the DME resolved the issue.  May I ask how you replaced the DME?  Does it have to be new (from dealer and programmed to vehicle) or used is ok?  And if used do I have to get the immobilizer also?   How did you do it is what im asking.  

[Loren]

P1503 Throttle Jacking Unit, Position Error – Signal Implausible

 

Possible causes:

– Short circuit in wiring harness
– Sluggish throttle (throttle butterfly and ports dirty)

 

[wickedst]

Loren thanks for your response.   I dont feel like its the throttle body as i have tried 3 separate throttle bodies and all three are clean.  The check engine code for P1503 can not be erased and immediately comes on before the engine even starts up.  I will try to examine the wiring harness from the throttle body to the dme and hope to find something.   Any help or insight you give me is much appreciated.  Would you happen to know the wiring schematics from throttle body to dme?

[wickedst]

i was able to find the wiring schematics.   I will check the wiring and let you know if i resolved the issue or need more assistance.  thanks.

[Loren]

DId you perform a throttle adaption after replacing the throttle body?

 

Perform adaptation:
1. Switch on the ignition.
2. Wait one minute. Do not press the accelerator.
3. Switch off the ignition for at least 10 seconds.
4. Read out the fault memory.

[wickedst]

Hello Loren,  thanks for all your suggestions.  I did finally fix the boxster.  I found the wiring schematics for the dme and with your first suggestion of a short circuit of the wiring harness.  I decided to work on the throttle body wiring to the dme.  I initially thought something was wrong w the dme as it was not sending the signal that i needed but upon further investigation and the intake  connections removal i found the issue.   Rats had chewed into the harness at two locations under the intake manifold.  I had the throttle problem and oil level sensor problem and both were attributed to chewed up wires.

I was able to repair the harness and i performed the throttle adaptation.   The engine started right up and problem fixed.   Thanks for your input.   Much appreciated.   

[Loren]