CEL P2096 P2098

[rkelly]

Hi Guys,

I will start by stating that all 4 oxygen sensors were replaced on my car ~ 1 year ago.

A few months back I started getting a CEL on my 986 Boxster. The code reported was P2096 (P2096 Signal Delay Time for Oxygen Sensor Ageing - Above Limit)

I cleared this error and after ~150 miles the CEL reappeared once again with the same code. I cleared it but it reappeared once again after ~100 miles. Unfortunately, this did not point me towards which of the 4 oxygen sensors was reporting the problem.

The fault reoccured 2 weeks ago (P2096). This time I decided to swap the 2 post cat oxygen sensors to see if that resulted in a different error code. IT DID! After 50-100 miles the CEL reappeared. This time the OBD II code was P2098.

P2098 Signal Delay Time for Oxygen Sensor Ageing, Bank 2 – Above Limit

My next step would be to replace the post cat oxygen sensor on Bank 2. Does anyone have a similar experience or any further suggestions on diagnosing the fault. Could the oxygen sensor fault codes be a red herring for some other problem with the exhaust system?

[rkelly]

Hi Rockster/bobsan,

There have been no other fault codes reported and the car is running well. The sensors that were replaced ~1 year ago were done by my local (highly respected porsche specialist). They appear to have a bosch part number on them. Those sensors were changed out at that time due to similar error messages. He has told me I can leave it back with him for further investigation.

In the meantime, I have some free time this week so i'll get under it and check myself for leaks.

Incidentally, there was a rattle/buzz coming from the exhaust a few months back. At the time I was worried it was coming from one of the CAT's. I gave everything a good thump and it turned out to be just a loose heat shield.

The car passed its annual MOT test last week. I noted the following from the emissions test:
CO idle: Recorded Value 0.020 % Vol (Required limits 3.50 % Vol or less)
HC: Recorded Value 65 ppm (Required limits 1200 ppm or less)

From those values you would assume that the CAT's are working fine?

I guess this is all irrelevant though if I have misinterpreted the DTC's. To be honest I have been trawling the internet to find instances of Porsche P2096 and P2098. The most prolific hits have come from Loren on either RennTech or Rennlist.

He gets his information from the Porsche OBD II manual. Here is an example of one of his many posts on this topic.

http://www.renntech.org/forums/topic/18073-p2096-p...

I will phone OPC today and find out what version of the DME is on my car and confirm what the DTC's are.

Thanks a lot for your input lads it is greatly appreciated

Cheers,
rkelly

[rkelly]

Rockster said:

If the emissions numbers are well below the failure thresholds things are working pretty good, at the time.

As an aside: I have been nursing my 02 Boxster with a weak converter through emissions testing for several years now. Nothing illegal, I just know how to hold off the CEL for a while.

Even so the converter is working pretty good (most of the time) because the readiness monitors are set to complete and if the converter wasn't working well the converter related readiness monitor would be set to incomplete and I think that's enough to fail the car.

P2XXX DTCs are given in the SAE reference I have and I quoted from that book.

What is the MY of your Boxster? I'll see if I have anything specific on those error codes for your car.

Sincerely,

Rockster.

Hi Rockster,

The Boxster is MY 2003. I called the OPC in Belfast to see if they could offer a definitive answer on the DTC's. They checked their manual for my car and told me the following:

P2096 Signal Delay Time for Oxygen Sensor Ageing, Bank 1 – Above Limit
P2098 Signal Delay Time for Oxygen Sensor Ageing, Bank 2 – Above Limit

According to my records the following took place:
17th May P2096
20th June P2096
31st August P2096
10th September P2096 (DTC cleared and Post Cat O2 sensors swapped sides)
20th September P2098 (Bingo!!! It looks like the fault has moved with the sensor position change)

Unfortunately, It has reappeared this week however, this time I have both codes showing up!? wtf?
9th October P2096 and P2098.... contaminated sensor threads???

When I spoke to the OPC they were keen to get it in their workshop for some testing. I have it on the ramp in the garage at the minute as I have been doing a caliper refurb this week. It would have been handy to do the O2 sensor change while I was at it.

Any suggestions while I have easy access to the sensors? Maybe I should just take a chance and replace the suspected faulty sensor?

Thanks again,
rkelly

[rkelly]

I didn't really do any further investigation. Shortly after my last post I swapped the post cat oxygen sensors back to the original configuration and cleared the fault code. I also decided to start filling up at a different petrol station. The P2096 fault code reoccured once in ~1000 miles of driving and I cleared it again. I'm sure that one of the sensors is bad but I never got round to replacing it. Last month I traded it in against a cayenne S as the wife needed a bigger car. I was really sad to see it go. It had been in the family for 10 years.... after 109000 very enjoyable miles the car was still driving beautifully.