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Engine management light 03 Boxster S

DavidHolden

DavidHolden

New member
Hi,

Being a Cayman S owner, I recently convinced my father to buy a 2003 Boxster S, which seemed like a good motor for 8k. It seems in great condition but the engine management / emissions light came on whilst test driving it. The small independent dealer (who was very helpful) that we bought it from sent it to his local specialist who replaced at least 2 of the lambda sensors and tightened the exhaust bracket (I believe the OBD codes suggested these were the problem). This seemed to sort it for a while. After owning it for about a month and doing a couple of hundred miles or so the light has come back on again, which co-incidentally happened just after filling up with super unleaded. The tank was not especially empty before refilling.

The dealer has suggested he takes it to the indy he uses in Kibworth Harcourt, Leics and following a conversation with them I think they intend to change the remaining two Lamda sensors. My reading on the net seems to suggest that failures of multiple sensors is unlikely and that the OBD codes may be misleading in that there could be another cause (MAF etc etc).

Is this a common issue and any particular problems to look out for? The dealer thinks it should be ok to drive around 20 miles or so to have it looked at again.

Thanks for any advice

Steve
 
As long as the CEL isn't flashing, it is OK to drive.

As you have read, O2 sensor fault code on both banks don't always mean sensor failures. It depends what the fault codes are. If they both record lean or rich mixture adjustment limits reached on both banks it could well be a MAF problem. UK cars won't trigger the CEL for a MAF fault. If you have PSM, then MAF faults will often trigger the PSM fault light though.

You also need to get the system diagnosed with a proper Porsche tester. Generic OBD2 testers don't usually record the Porsche-specific fault codes. With a Porsche tester you may find a fault recorded for the MAF (depending on the ECU version), but it can be used to monitor the MAF output values, which will tell you if it is over or under reading (hence causing the rich or lean errors).
 
Yes, yes, and no. Yes it will diagnose a faulty MAF on a 986. Yes it will display actual values for TPMS (which should include battery state), but no, it won't code new Porsche TPMS sensors - not that you may need to. [;)]

There is a feature matrix for all models on the Durametric site, but it would be best to drop them an email to check that it can test the battery state before taking the plunge.

Edit: Bear in mind it is only the Professional version which will code control modules.
 

ORIGINAL: Richard Hamilton

As long as the CEL isn't flashing, it is OK to drive.

As you have read, O2 sensor fault code on both banks don't always mean sensor failures. It depends what the fault codes are. If they both record lean or rich mixture adjustment limits reached on both banks it could well be a MAF problem. UK cars won't trigger the CEL for a MAF fault. If you have PSM, then MAF faults will often trigger the PSM fault light though.

You also need to get the system diagnosed with a proper Porsche tester. Generic OBD2 testers don't usually record the Porsche-specific fault codes. With a Porsche tester you may find a fault recorded for the MAF (depending on the ECU version), but it can be used to monitor the MAF output values, which will tell you if it is over or under reading (hence causing the rich or lean errors).
Click to expand...

Thanks - that's really helpful. We will
see what sort of OBD reader they're using. The car was originally imported from Cyprus when new if that makes any difference?

Steve
 
I don't think it makes any difference to the engine or ECU that it was built for the Cyprus market. The fuel map should be the same standard (EU3 iirc) program for Europe. There were a lot of imports at that time by non-franchise dealers, so not unusual. There can be minor differences to the alarm system, but that's about all.
 
In case you didn't know:
If the CEL is on then the fault code should be logged. Cheap, generic OBD readers won't really point to the problem, you need Durametric, PIWIS etc...
The indy should be able to look at the levels from the 02 sensors to verify they are working correctly.
A common 02 failure is the heating element. You can check this at home with a resistance meter. Typical 'good' values 4-10ohms.
MAF sensor failures only show up on OBD when they are really bad. The early clue is the way the car drives i.e. badly.
You can look at actual values from the MAF on OBD - this will indicate health.
 
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