Do CEL code clear by themself?
 

Hello all

CEL appear (2000 S), stop at indy to have it check. He told me it's O2sensor related without telling me exactly what code. He did not had time to invest about it and I had to go back Home 300km away. Back Home CEL is still on and stay for 2-3 rides. Then I connect my actron to read them, P1126, P1133. I did not erase them, but at the next ride, CEL is off.

Could it clear by itself?

Thanks
Chris

Them 2 codes as a pair indicate a bad maf .
Try removing and cleaning , and check air filter while your in there anyway .

It could also be vacuum leak , low fuel pressure etc .
But the common one is maf .

Them codes shouldn't reset afaik , although some codes will after the fault has been rectified for a few miles . Loose gas cap etc .

Out of interest , did you fill up whilst awayn, then fill up with your normal fuel upon your return ???

MAF and intake leak are out of the equation. MAF is new and tested and intake has been smoke test. Exhaust leak are also repair. It was part of the original problem that my indy has been investigating. We though everything was finaly good, and then CEL is on after about 650km.

He think O2 sensor might be worn or not heating properly, but he need to connect to the car and do testing with is computer.

I've heard some CEL could appear and disappear after a couple of cycle if the problem is not back, thats why I was asking

Chris

Some do , but I'm pretty sure anything emmissions related doesn't .
In all honesty youre better off talking to your Porsche specialist than listening to some half drunk English guy sat on a porch in Southern California on the Internet :D

It will be simple enough to test the lambda probe .
I think i remember jeff posting instructions in this section recently ?

I think the aos can also throw them codes , but to be honest , I'd try another known-good maf before I discounted it being good just because its new and tested ok ....
Is it a genuine Porsche maf ???

Yes genuine MAF. AOS is also new 2 mouths ago. Everything is being tested on a Porsche PIWIS system. My Indy do so many Porsche that he lease the system from Porsche. So I'm fairly confident when he says MAF is good. Longue story short, MAF was reading stange (19 instead of 14 x unit). After testing every sensor, they found a faulty ground. Correct the ground and reading was perfect, still they left the brand new MAF even after confirming the old one was good, as a safety)


O2 sensor might be related to all the oïl burning after AOS failed, or simply they are old, or maybe wiring. He says too many option to simply change them, he need to test stuff before.

I guest I will have to do an other 300km trip to see him.

Thanks
Chris

From what little I know them two codes in combination meani issues eith side of the engine ,
That's why I said maf .
It is an obvious choice ,

It could be vacuum leaks , lambda wiring broke down , aos piping .

Interesting stuff .
Once the experts on here have given advice , pease make sure to tell us the results .

Sorry I could not have been more help .

Ian

all CEL codes will clear themselves if the perimeters for setting them are either self corrected (which doesn't happen often) or enough key cycles have passed without a fault. check your fault code history to see which codes set and cleared themselves.

The Bentley manual describes how they clear themselves if the error conditions don't repeat for the next X drive cycles. I have got a couple that show up from time to time, and then they clear themselves. Since I have been to FL they haven't shown up, until the other day :) I haven't even read them yet;; I think it is one of the secondary O2 sensors. I have all the troubleshooting steps, but just haven't fooled with it since the car is running great, and they haven't been on (until the other day, sigh...)

Steve