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Cranks but won't start :( Help Please

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1997 Boxster - Here is whats going on:

Everything has been running fine. The other day I was driving around. Then Stopped and filled up with gas. Went to my office to pick up a few things. Went out to leave and it won't start. Cranks just fine, battery sounds strong, just will not start. I call my brother-in-law comes a little while longer to see whats going on. He starts it after one or so attempts and it starts. We let it run for a while. Everything sounds great and normal. You can rev it, no problems. So he leaves and says well maybe it was flooded. Makes sense, not sure hot it got there but possible. I go inside to grab a few things in my office and get ready to leave. Just to make sure, I turn the engine on and office a few times. Starts right up no problem. I start driving, a few minutes later... all lights go on, engine completely shuts down. Same thing, cranks but won't start.

Day 2 -

Next day, I've decided to go to the office and have it towed to my brother-in-laws garage to have him take a look. But... I decide to see if it starts. Started right up, first try. Turn it off and on a few times. No problems. Drive it around my building twice, no problems. So I drive it all the way to my brother-in-laws garage... 30mins. I stop at my other office along the way to remove the hard top and store it. then go to the garage. No problems.

At the garage. He cleans the EVO air filter (it was pretty dirty), he cleans the MAS & MAF, he cleans the carb.

Yesterday I picked it up. It ran great! You could tell it was running smoother from the cleanings. My wife and I drive to my parents, then we go to eat, then we drive home. About one hour we drive. Just minutes before we get home... all lights go on. Lucky there was a parking lot where it stalled and so I quick navigated in there and parked. Same thing, cranks... won't start. Just went a little ago to try to start the car. No luck. Now she just cranks and will not start :(

So the magic question is... Does anyone know whats going on or have had this problem before??? Is a sensor getting hot and failing? Someone said maybe the ignition switch, but I was thinking that is not the problem because my key is not stuck or anything and the car shut off as I was driving but I am not mechanically savy so I am not sure.

Thanks so much for any help you guys can give!!!


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So much it could be, loose or bad connection, relays etc. One thing that unlikely is flooding, I've know fuel inject cars won't let you flood them+the implication is that you cranked away on it till you flooded it...begs the question, why wouldn't it start in the first place.

One thing, has rained? do you have a leak, water under the seat? That floods your security box down there and depending on how much, can wreak havok or kill itself. My guess though, bad connection including ones in the ignition switch. or in a relay or connector.

Regards, PK

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  • Moderators

I would check the DME relay, fuel pump relay and fuses to start with. A quick check with a good diagnostic tool is recommended too, fault codes are crucial for a good and reliable diagnosis.

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Fuses are all good. I have a dumb question. I have the Durametric device. Gonna hook it up. If the engine will not start, do you think the CE light could still be on for the device to tell me a code? Reason I am asking is before when the engine would start up after I let it sit overnight, there were no CE or other lights. Thanks! I am gonna give it a shot within the hour and cross my fingers it tells me something so I go on a wild goose chase.

Edited by PABoxster
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So I plugged in the Duremetric and crossed my fingers that it would read any faults and it did. Can anyone tell me the approximate costs for parts and difficulty in repairing this problem?


Porsche fault code 660

CAN timeout - Instrument Cluster


Porsche fault code 39 Immobilizer

Thanks again for everyone's suggestions!


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  • Admin

P1602 Voltage Supply - Open Circuit

Probably an old fault from a battery change.

I would erase this one and see if it comes back.

P1571 Immobilizer - Open Circuit / No Sign

Possible causes:

- Open circuit in wiring between DME / no signal. control module and alarm system.

- Short circuit to ground or short circuit to B+.

- Alarm system control module faulty.

Chances are this is your problem.

Did your alarm control box under the drivers seat (LHD) get wet? or is the carpet wet?

If so, it is likely ruined.

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I will check the carpet but I am thinking that it is not wet. No reason for it to be wet. I have never even used the factory alarm unit. When I purchased the car, the dealer only had one key and it did not unlock or lock the doors so they had a second spare key made but that too did not have a remote on it. I had an alarm put in from tweeter over 5 years ago. How much will it cost to have this alarm control repaired or replaced? Any ideas? Could the chip in my key be faulty as well?

Thanks for your help!

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  • Admin

It does not matter if you ever used the alarm - that box also has the central locking circuitry and the immobilizer.

It would be best to find someone with a a PST2 or PIWIS that can confirm the problem. In a few rare occurrences the problem was corroded connections that could be cleaned - but that still not be the best solution. In the long run it is best to get the new immobilizer and make you keep the top drains clear so it odes not happen again.

Are you in the US?

A new immobilizer control box is about $350 US MSRP. It will also require about 1 hour of programming for your car and to match your keys to the new immobilizer.

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Yes, I am in the US. Do you know where I can get the immobilizer control box besides the Dealer? Is that $350 from the dealer or an internet price.

Is it easy for me to get to the immobilizer to see if there is corroded leads? I know it is under the seat but I have never taken the seat out before and not sure how hard it is to remove the seat.

Thanks so much for all the great posts! Yours seems to make the most sense so far.

Oh, and no way it would be a faulty chip in the key right?



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You don' actually have to take the seat out your seat, you can reach in and under and pull it out from behind but youhave to know what to twiddle and how. The seats really easy to take out. Slide it back , and you either see plastic covers on either side at the end of the tracks (in which case take them of) or just weird star bolts of some sort (forget) sticking up. Take them out, roll the seat all the way forward and you'll see and do the same. There's also a wiring harness to disconnect. Your done.

The carpet is on a pretty thick foam pad under the carpet, it can hold a lot of water without getting the carpet wet.

You must have it wet recently for it to cause such brief failure. No-one believes me but you can get them wet and not ruin them if you catch it soon enough. I had one that I pulled out thrice right after storms, completely full. Dumped it out dried it out etc asap. It worked. I'd take it out and dry it out and be on your way. Fix your leak/drains to.

But your not me so you might look online for a replacement.

Regards, PK

Regards, PK

Edited by pk2
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  • 5 weeks later...

Chris, before you spend a penny it would be best to as you have read to check for water contamination 1st and if found you have your answer.

If not you might want to look at the seat and see if the 3 pieces of plastic that sheild the underside are broken especially on the driver right side of the seat next to the center console.

I had a very similar situation as you described but my 986 gave me an indication when the windows 'twitched' and wouldnt go all the way up or down then pffffttt they were ok UNTIL I drove it normally and then DEAD...all the lights came on....plenty of juice in the battery but alas it would not crank over.

I had it towed to the local dealer and in 15 mins they had the seat out and saw the problem. That silly piece of plastic had broken and had caught on the wire harness and pulled out ever so slightly one of the wires and it IMMOBILIZED the car. 1 hour in labor and $85.00 in parts fixed the problem. I hope this helps you find the trouble.


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  • 2 weeks later...

can anyone tell me where the dme relay is i have recently upgraded my car to a 2002 3.2 engine the complete wiring loom and electrics have been swapped but the ecu alarm and transponder came from another car the alarm works with the key but am unbale to turn the car over all the lights on the instument cluster light up but it doesnt even try to crank


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You need the DME, Alarm control box and transponders (Tiptronic to manual and vice versa is not possible) from the donor car to start with. The car should crank with that, if he doesn't, search the problem elsewhere (wiring - connectors etc.) A diagnostic tool should help *** well.

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You need the DME, Alarm control box and transponders (Tiptronic to manual and vice versa is not possible) from the donor car to start with. The car should crank with that, if he doesn't, search the problem elsewhere (wiring - connectors etc.) A diagnostic tool should help *** well.

my dme alarm box and transponder all came from the same car. im not convinced that the dme is getting power can someone tell me where the dme relay is so i can swap it and test also which one of the dme wires is the power so i can stick a multi meter on it

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