03 Boxster S Check engine light
Discussion
Hi,
I recently convinced my father to buy a 2003 manual 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. The car is driving fine.
Thanks for any advice
Steve
I recently convinced my father to buy a 2003 manual 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. The car is driving fine.
Thanks for any advice
Steve
03 Boxster S dme maps have an anomaly that causes the check light to come on too early durng adaption. Take the car to an OPC, get them to check the PPN TI in gr.2 ; fuel and ignition/exhaust. I would bet the dme needs to be remapped to the latest version and the o2 sensors replaced were probably fine (should have been scoped before replacement but who checks when the fault code MUST be right).
If you're near Swindon next week I'll do it for you
If you're near Swindon next week I'll do it for you
Pope said:
03 Boxster S dme maps have an anomaly that causes the check light to come on too early durng adaption. Take the car to an OPC, get them to check the PPN TI in gr.2 ; fuel and ignition/exhaust. I would bet the dme needs to be remapped to the latest version and the o2 sensors replaced were probably fine (should have been scoped before replacement but who checks when the fault code MUST be right).
If you're near Swindon next week I'll do it for you
Pope talks sense and has made a very kind offer, if I was near Swindon I would accept. If you're near Swindon next week I'll do it for you
Thanks for all the info folks - great to know there's so many genuine people out there offering assistance. He lives on the Lincs/Leics border and as he only bought it recently he did take it back to the vendor's indy who said the fault code reported a rear O2 sensor. He said he thought this was unlikely to be the issue, swapped them round and reset it. He reckons if it comes on again and it reports a different sensor it probably needs a new ECU, although from the above it sounds like it may just need an update.
Thanks again, will see how it goes. It seems an awesome car for 8k, considering I paid over 50k for my Cayman S, which is clearly a better motor but perhaps not THAT much better :-)
Thanks again, will see how it goes. It seems an awesome car for 8k, considering I paid over 50k for my Cayman S, which is clearly a better motor but perhaps not THAT much better :-)
Rockster said:
REALIST123 said:
Is that so? How does that work then?
The DME runs a pressure test to ensure the tank is vapor tight. With the cap off the pressure test fails. This turns on the CEL.Seems a bit OTT to me.
REALIST123 said:
Interesting. Do you know how it checks the pressure? Presumably it links this to temperature which will significantly vary the vapour pressure or dies it just report a failure if the pressure is atmospheric?
Seems a bit OTT to me.
There are two basic techniques. One involves raising the pressure in the tank using a small air pump another involves lowering the air pressure using engine vacuum. In both cases once the target pressure is reached (and there is probably a time component to this) the pressure is monitored. Too much change in pressure (a drop in a pressure test or a rise in a vacuum test) and this is a failure.Seems a bit OTT to me.
Of course, failure to reach the starting target pressure is a leak too. A big leak.
Open to atmosphere fuel tanks and hot fuel systems (carburetor float bowls when engines had carburetors) open to atmosphere used to contribute greatly to hydrocarbon emissions. Another large contributor was the air escaping from a fuel tank during fueling.
(Some vehicles, my 03 Turbo for instance, have a fuel cooler that is cooled by the A/C. When the A/C is on some chilled refrigerant is routed to this fuel cooler to help keep the fuel in the fuel tank cooler and keep emissions down among other benefits.)
Most emissions regulatory agencies have strict limits on how much hydrocarbon a vehicle can emit over a period of time when the vehicle is in a special enclosed/sealed test chamber and pity the poor automaker and his vehicles that fail this test.
So, OTT? Well, opinions differ.
Rockster said:
There are two basic techniques. One involves raising the pressure in the tank using a small air pump another involves lowering the air pressure using engine vacuum. In both cases once the target pressure is reached (and there is probably a time component to this) the pressure is monitored. Too much change in pressure (a drop in a pressure test or a rise in a vacuum test) and this is .
So which system is used on Porsches and where is the pump located? USA cars have a different system to UK variants - the tank pressure is not measured / regulated in the same way as it is not a legal requirement. From 02 on most Porsches got a returnless fuel system (fuel is supplied to the engine and the pressure is regulated but no fuel is able to return to the tank like earlier systems - this reduces evaporation through warming of the fuel by the engine).
REALIST123 said:
So which system is used on Porsches and where is the pump located?
I think Porsche uses the vacuum system as I've never found a pressure pump anywhere in the parts diagrams.Furthermore test steps for trouble shooting fuel tank ventilation problems refer to connecting a vacuum pump to the system to check for leaks. There is not one test step that refers to switching on a pump to pressurize the vent lines or the tank.
The tank can develop positive pressure as the fuel heats up from ambient temperature and from being heated by the fuel pump. The system might rely upon this natural build up of pressure to test for pressure leaks too.
I have a 2002 3.2s boxster and had the same problem when I bought it 2 years ago. Took it to main dealer porsche who connected it to their laptop and said the problem was either lambda sensors or ignition coils. Wanted £1000 to do the work. Took it to a porsche specialist who said he was sure it wasnt the cause of the ignition light coming on. He found (believe it or not) that the problem was a hose which is just under the starter motor which had came loose . He put it back on, tightened it up and the light has never came on since !
I was interested in this thread and the comments/advice as I have a similar problem. I have a 2004 Anniversary Boxster which I bought last November and have used it on about nine track days. The day after a track day in June the emission light came on. I took it to the "indy" where I have had the car serviced and they put their diagnostic kit on it and it came up with defective oxygen sensors. The guy in the garage was not convinced and "reset" the light and suggested I see how I get on. I did a couple more track days in France (driving there and back) and had no problem. Last week I did another track day (Donington Park) and the day after on the drive home the light came on. I have one more track day booked before the car goes to the "indy" for a full service and also sort out the compressor on the A/C as this is making a noise although the A/C is working. The noisy compressor only started when I was driving up to Donington so the comments about the A/C playing a part in the emission control could be pertinent. But if anyone has had any recent experience of this problem I would be interested to know. May have to cancel the last track day.....
Some things have changed since 2013....
My offer wouldn't stand in Swindon any more - I am in Reading now - the Swindon lads would still be a valid choice if location is easier (though only 40 miles different if you are further afield anyway)
2004 cars didn't suffer the map anomaly like the 2003 cars; but the easy way to check is the RKAT values - they start at 0.00; if they increase in a positive direction an adaption is being made to richen the mixture; negative adaption reduces fuelling, weakening the mixture. The erroneous map placed the RKAT values at 3.00% meaning a very small window until CEL (threshold is +/-4.50%).
I have lost count the number of times I've seen O2 sensors fitted because the fault codes say so.
My offer wouldn't stand in Swindon any more - I am in Reading now - the Swindon lads would still be a valid choice if location is easier (though only 40 miles different if you are further afield anyway)
2004 cars didn't suffer the map anomaly like the 2003 cars; but the easy way to check is the RKAT values - they start at 0.00; if they increase in a positive direction an adaption is being made to richen the mixture; negative adaption reduces fuelling, weakening the mixture. The erroneous map placed the RKAT values at 3.00% meaning a very small window until CEL (threshold is +/-4.50%).
I have lost count the number of times I've seen O2 sensors fitted because the fault codes say so.
Hi Doc, I would question the diagnostics, as its almost unheard of for all sensors to fail.
I would ask them what the fault codes were, and look at the RKAT value, which should ideally 0 but can go to +/- 5%, when it reaches the 5% adaption value, then it will turn the engine management light back on.
Chris
I would ask them what the fault codes were, and look at the RKAT value, which should ideally 0 but can go to +/- 5%, when it reaches the 5% adaption value, then it will turn the engine management light back on.
Chris
Pope said:
Some things have changed since 2013....
My offer wouldn't stand in Swindon any more - I am in Reading now - the Swindon lads would still be a valid choice if location is easier (though only 40 miles different if you are further afield anyway)
2004 cars didn't suffer the map anomaly like the 2003 cars; but the easy way to check is the RKAT values - they start at 0.00; if they increase in a positive direction an adaption is being made to richen the mixture; negative adaption reduces fuelling, weakening the mixture. The erroneous map placed the RKAT values at 3.00% meaning a very small window until CEL (threshold is +/-4.50%).
I have lost count the number of times I've seen O2 sensors fitted because the fault codes say so.
Hi Pope, My offer wouldn't stand in Swindon any more - I am in Reading now - the Swindon lads would still be a valid choice if location is easier (though only 40 miles different if you are further afield anyway)
2004 cars didn't suffer the map anomaly like the 2003 cars; but the easy way to check is the RKAT values - they start at 0.00; if they increase in a positive direction an adaption is being made to richen the mixture; negative adaption reduces fuelling, weakening the mixture. The erroneous map placed the RKAT values at 3.00% meaning a very small window until CEL (threshold is +/-4.50%).
I have lost count the number of times I've seen O2 sensors fitted because the fault codes say so.
I hope you don't mind me asking... What is your back ground? Do you work for a Porsche specialist? You seem very knowledgeable!
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