Check engine light and fault code.

[paterson12]

Hello.

Last night while driving home my check engine light illuminated. I plugged in my cheap OBD code reader and pulled a code; P2098 "post catalyst fuel trim system too lean bank 2"

Im assuming this is just a Lambda sensor? Could it be anything else?

Ive actually deleted the code and the light has gone. Chances are it'll come back but you never know, worth a try!

Many thanks
Joe

 

[jmaddox]

I had similar on the day I bought my Cayman S. Needed a new catalyst and OPC charged £2200 to replace one side only including new sensor. Luckily dealer picked up cost. Fine since.

I would start start by filling with Shell Nitro and monitoring fault codes. The problem with obd fault codes can be you sort one thing and then another pops up.

 

[paterson12]

I have heard about the cats on the US forums.

The fault code I received was the front Lambda sensor (in front of the cat) and there's no rattles or weird noises from the exhaust system so I'm doubtful that the catalyst is knackered.

Nevertheless you're right, I will monitor it.

 

[Motorhead]

Certainly sounds like a possible lambda sensor fault Joe. Put in some decent fuel and give it a good blast to see what happens and also I'd check for an exhaust leak on that bank. It could just be a loose clamp due to bolt corrosion or failure. What year/mileage is your car?

If John was charged £2,200 for just one cat and sensor and it turns out that you need a replacement, I'd be inclined to look for a new after-market system at that price as the second cat might start to be troublesome in the near future.

Jeff

 

[paterson12]

I always run the car on Shell Nirto+ anyway (personally I think it makes I noticeable difference) and I've recently had the exhaust bolts/gaskets changed on the exhaust flange with no evidence of cracks or leaks anywhere.

I did notice a considerable difference in the in the prices of the Lambda sensors. Porsche: £120, Bosch £85 and Bosch 'universal': £50. I'm thinking that the universal are probably adequate but I stand to by corrected if anyone doesn't recommend that option??

As for the catalysts, I would probably find some salvage replacement or as Jeff has said, aftermarket replacements if they do turn out to be knackered.

Car is an 2006 with 31500 miles.

 

[Motorhead]

Joe,

If the bolts and gaskets were replaced recently it may be useful just to check that everything is still tight after the bedding-in process.

From what you say I think it's doubtful that the cat has failed on such a low mileage car, but you never know; especially if the car has been used for very short runs and the cats haven't got up to full temperature.

Sorry, I can't advise on the Lambda sensor option but I would think that Porsche just adds £35 to the Bosch-supplied item.

Jeff

 

[paterson12]

I did check the flange/bolts as I did think that the bolts may have come loose but all was still tight with nothing obviously wrong.

The car car has come up with a false warning before. 'Check oil level' once flagged up, it quickly disappeared and the oil level was fine (between the level markers on the digital display) so I'm wondering whether this was also a false warning. The 'check engine light' is still off after the reset, if it reappears then I will probably swap the Lambda sensor and take it from there. Maybe a software update is required if it never reappears.

The car car has done 2k miles a year according to the MOT's. The cats may still be at fault but I'm remaining optimistically hopeful that they're not.

 

[jmaddox]

The cleared check light will usually come back on the third full heat cycle. The supplying dealer bought two after market catalysts at about £1200 for my car but the installer/fitter refused to install them as the fit and finish was so poor. Hence the OPC solution.

 

[paterson12]

Fortunately I've got a 30 mile drive this afternoon with stops inbetween so I'll see if the light reappears.

Thats useful to know. Were they performance cats or just non-OPC replacements?

 

[jmaddox]

It has to be a full heat cycle from fully cold to fully hot. They were I think the 200 element semi sport cats. The other side cat had already been replaced by an OPC before I bought it for similar money. It's no wonder early boxsters are being scrapped when the cats fail. Quite ridiculous really they cost up to £4K a pair fitted.

 

[paterson12]

Update: the 'check engine light' hasn't returned but unfortunately my OBD reader now has a code: P0431, shortcoming in the catalyst :-(.

This is a pending code and hasn't yet matured into a full fault code. I will delete it and see if it reappears.

So much for being optimistically hopeful

Joe

 

[jmaddox]

That's not good news. If you do start replacing bits consider the before and after sensors first. These usually have to be replaced anyway as they are often rusted in so badly they cannot be removed and refitted to new cat.

 

[paterson12]

I've decided to delete the pending code and again, see if it reappears in the near future.

You're right though, I will swap the before and after sensors if these codes persist before changing the catalyst.

To be honest I'm not particularly technically minded but these fault codes seem a little random. Logically I would have thought that if the cat was faulty I would get a rear o2 sensor fault, a front o2 code or all three fault codes occuring at the same time. I've done 90 miles today with the original o2 front code not making a reappearance since yesterday. I've also done 25 miles since deleting the catalyst code with no reappearance oF that or any other code.

Anyway, I guess I'll keep monitoring it.

 

[jmaddox]

I am sure you are doing the right thing in monitoring the codes. Sometimes it settles down on it's own. Fingers crossed for you. Mine was a low mileage car as well and I am sure they prefer being used on a regular basis.

 

[C2dweller]

The car has to go through a number of driving cycles (3 I believe) before the code is confirmed or CEL is illuminated on the dash ... about 350-500 miles for nirmal driving. More serious faults will illuminate sooner.

Early Caymans do seem sensitive to CAT faults. I believe a software update

helps with this but cannot confirm. If this were the fault I would expect an 'ageing fault'.

As well as looking for leaks on the exhaust side, do look on the inlet side and possibly clean the MAF. This might be a slim chance if you have just one lambda side at fault, but cheap and quick.

KR Lee

 

[paterson12]

I have heard that the 2006 caymans had different cats to the later models which causes fault codes which was cured with new cats and a software update but that was on the US forums.

Ive got 1000 miles worth of driving next week so we'll see what happens.

I will keep you updated.