BigHeadDennis

Any thoughts or suggestions to my problem? I'd greatly appreciate any help or experience you might have...

When OBD-II came out, I just KNEW that I would get annoyed by this eventually. So, of course, the "check engine" light came on recently, just after the car passed out of the warranty period.

I went to my friendly Ferrari mechanic and borrowed his OBD-II tool (a windows program, a serial cable, and an OBD-II adaptor). Plugged it into the 996, and it read two proprietary codes - one that was stored (P1125) and one that was active (P1123).

Thanks to the list provided by Stephan Kaspar (www.imagineauto.com), I know that P1125 = "Oxygen Sensing Adaptation, Upper Load Range, Bank 1". But P1123 wasn't listed (???).

I then "cleared" the memory, which reset the light. After three days at Watkins Glen, no check engine light re-lighting up. But then my wife takes it to work a couple of times, and voila, it reappears.

So I hook it up to the generic OBDII tool again, and there are two error codes: P1124 and P1126, each read as "O2 sensing range 1", P1124 for cyl 1-3 and P1126 for cyl 4-6.

I cleared the codes, but then the light came back on again as my wife was driving to work. I guess an O2 sensor needs to be replaced? Any other ideas/suggestions? I had also heard that the MAF sensor is a weak spot on the '99 996. Is that tough to replace? Can I do it myself?

My service advisor at the dealership tells me that O2 sensors are NOT covered under the federally mandated 8 year emissions warranty. Darn it. So, how tough is it for me to replace the O2 sensors or MAF myself? And given the error codes, how likely is it that replacing the sensors will fix the problem?

thanks!

vty,

--Dennis

Loren

According to my troubleshooting tree:

P1124 Oxygen Sensing Adaptation Area 1 (Cylinders 1 - 3) - Rich Threshold
P1126 Oxygen Sensing Adaptation Area 1 (Cylinders 4 - 6) - Rich Threshold
Meaning: Fuel/Air mixture is so lean that it has reached its rich threshhold. (i.e. it can not richen the mixture enough).

Potential causes: Intake air system leaking, fuel pressure too low, fuel pump volume too low, fuel injectors plugged.

Have you done anything with the air filter/intake?

Ash996

I had the same issues about two months back. After several trips to the dealer and an indenpendant shop (my car is also out of warranty), the MAF was replaced and the problem went away. Basically the light kep[t coming on and being reset, then it would come on again. Be careful not to replace anything that doesnt need replacing. The O2 code could be a symptom of another issue (bad MAF for example). If it is any help, I had some hesitation at cold start up which was the real clue to let us now that the MAF was not sensing properly and had been shot. I think it is easy to replace but very expensive to buy from the dealer (~$500)
Good luck.

stratpa

This is not as technical an answer but I have heard that certain forms of car wash can damage the sensor and set it off. For instance if you try to steam clean the engine compartment you are bound to cause such an issue.

Loren

Uh..... folks the oxygen sensor detects the fault (based on the air/fuel mixture) -- it is NOT the fault.

Alfie

Dennis, Check your PM's...

Eric - Plug Guy

Had this happen on my 996 a few months back, and first the MAF was replaced, but light came back. Next repair was a replaced Bellows Tube. Parts are about $20, labor takes 30 mins but you'll get charged an hour or two.

Was frustrating, but my tech would not give up. Make sure they take a look at that as well.