OBDII codes

[Jim]

Love the site!

Maybe you can help.

I have a 99 C2 and my check engine light keeps coming on. Bought a scanner to get codes today, hoping I could fix this myself. (Thinking MAF sensor or something easy)

Here are the codes I got

P1125 = Oxygen Sensor Adaptation, Upper Load Range, Bank 1, Above Limit

P1123 =O2S Sensing Range 1 Cyl. 1-3

Seems to me like I have an air leak, and I did find one on a hose that was abraided on the air intake inlet.(looked to my like a PCV hose) I taped the holes there were three pin holes in the height of the ridges. Cleared the codes and about an hour later the light is back on. I'm thinking another leak somewhere but it is so hard to see these hoses.

Do these codes seem like a vacuum leak?

Is there another common area to develop a leak? ( I found posts on bellows before, but not sure where that is)

Do the ranges above indicate O2 sensor before cat or after ? ( I believe there are four)

Should I be looking on the right or left ? (which side is Cyls 1-3 on )

Any help would be appreciated, Jim

[Loren]

Hmmm... my code list says:

P1123 Oxygen Sensing Adaptation Area 1 (Cylinders 1 - 3) - Lean Threshold

P1125 Oxygen Sensing Adaptation Area 1 (Cylinders 4 - 6) - Lean Threshold

This would mean that the fuel/air mixture is so rich that sensing is up to it's lean threshold.

My list of probable causes are: fuel pressure too high; fuels injector(s) leaking; EVAP canister purge valve open.

Could be the charcoal canister (which should be covered under emissions warranty) or fuel pressure too high because of dirt stuck in one of the valves or a bad fuel pressure regulator vacuum connection. In the end all of these may be covered by your emissions warranty (unless it was caused by a dirty fuel filter/fuel).

[Jim]

Man your fast!

Guess I'll make an appt.. I'm not the detective I thought I was. I have an extended warranty that may help if not emmissions related. Just a pain to bring it in, and I love fix things myself.

Would spark plugs cause this( too weak to burn )? they are due for a change.

Would you run fuel system cleaner, like techron?

Where is the fuel filter?

I got the codes off the website that came with the scanner, and could not find porsche codes listed on the web. Do you have a place I can reference these?

Thank you for your help.

Jim

[Loren]

Would spark plugs cause this( too weak to burn )? they are due for a change.

Would you run fuel system cleaner, like techron?

Where is the fuel filter?

I got the codes off the website that came with the scanner, and could not find porsche codes listed on the web. Do you have a place I can reference these?

I doubt even really bad plugs would cause this. I think the car would run really bad first.

I use Techron about every 4,000 miles... cheap insurance.

The fuel filter is at the front end of the center tunnel of the car. It's under a belly cover... If you get the car up on the lift, or on jack stands, follow the fuel lines out of the tank, it's the first stop the main supply line makes. The correct fuel filter for a MY99 C2 is: 996 110 253 01

I get my Porsche P-codes from my subscription to AllDataDIY.com AND my Porsche OBD II Manual.

[Jim]

Thanks for your help Loren

I spoke with my dealer today and they want to replace the MAF and oil separator as well as the hose I mentioned earlier. They also want to reseal my oil pan. all for the cost of over $1200 They stated the emissions warranty does not cover this nor does the extended waranty I purchased through them . I'm thinking of just fixing the oil separator and other hose then see if throws another CEL. They want $850 for MAF alone.

[Tool Pants]

According to my 2002 price list the full list price of the sensor for a C2 is $231.55 and for a C4 it is $171.20. Guess I will not be buying parts for your local dealer. :angry:

This is the fuel filter for future reference. A pain to get to if the car is not on a lift but it can be done if you are thin. Jeff

[Jim]

Thanks Jeff

Do you know if changing the MAF is simple ?

The dealer said it would take an hour, but I can't believe it.

I will order one and install it myself unless very difficult.

[Loren]

5 minutes to change... 55 minutes to hook up the PST2 and make sure they were right :huh:

[Flakarter]

Loren: I am new to this forum and just bought a used 99 C2 last week, with 19k on the odo. It has now been diagnosed with a P1123 code by the dealer. :angry: You said your Alldata reference shows that code as a rich condition and that the car is trying to lean out the fuel mixture to compensate. That sounds like what my dealer said: "Detected 02 sensing fault. Taking away fuel because mixture is too rich. Reccomend replacing mass air flow sensor..."

The sensor is, like you said, a 5 minute R&R (had it out yesterday to get the part number).

Question: You indicated that it was 5 min to R&R, but 55 min to hook up to the PST2 and make sure that is the problem. What is a PST2, and exactly what are they doing for 55 minutes? Does it mean that I can't replace the sensor becuase there is some electronic equipment that needs to confirm the repair? I was hoping that I could simply replace the MAF sensor, have the check engine light turned off (code cleared???), and then simply see if it comes back on. I know that is low tech, but it pains me to pay $500 for a part that costs $200-300, and I can install it in a heartbeat.

I have a copy of the computer printout from the computer diagnosis. Does that provide any additional information that might help?

Thoughts?

Thanks

Dean

[Loren]

Question:  You indicated that it was 5 min to R&R, but 55 min to hook up to the PST2 and make sure that is the problem.  What is a PST2, and exactly what are they doing for 55 minutes?  Does it mean that I can't replace the sensor becuase there is some electronic equipment that needs to confirm the repair?  I was hoping that I could simply replace the MAF sensor, have the check engine light turned off (code cleared???), and then simply see if it comes back on.  I know that is low tech, but it pains me to pay $500 for a part that costs $200-300, and I can install it in a heartbeat.

I have a copy of the computer printout from the computer diagnosis.  Does that provide any additional information that might help?

The PST2 is the ($8000) Porsche diagnostic computer. It does much more than OBDII as it is used for the ABS, OBC, Instrument Cluster and new MOST bus computers.

Your MIL and fault can likely be reset with any commercially available scan tool. The 55 minutes I spoke of is really to check that another fault (same or different fault) is not triggered after replacing the suspect part. The fault number usually points to a list of suspected causes -- so if the dealer told you MAF sensor that is likely at the top of the list. The dealer would do the same, replace the part and see if you get another fault... then if you do replace the next item on the list etc. So, you can certainly do this yourself but if it throws another MIL and fault you will then need to diagnose that fault also.

[Flakarter]

I guess I don't have much to lose by replacing the MAF myself. If I replace the part, and have the sensor reset, and it comes back on, then I'm no worse off (in fact better off - saved $200-300 from dealer's $500 estimate). then back to the dealer for the next diagnosis (which will then probably be something I can't replace this easy).

Thanks for the reply Loren. :thumbup: Just amazingly helpful.

Dean

[Loren]

You can check out this $125 scan software and cable (if you have a laptop to use)...

See this post