Over the weekend I was completing another trip to the mountains in NH, and after exiting the highway I noticed a CEL(non-blinking).Luckily, I carry a code reader with me in my '99 Porsche and it read P1123(which indicates a lean threshold in cylinders 1-3...oxygen sensing adaptation area 1). This CEL has come on about 4 or 5 times in the last 2 1/2 years of ownership. Can someone tell me what is going on, and whether I should start worrying? .By the way, I reached triple digit speeds a few times for short distances and then saw the CEL after stopping at a light a few minutes later.TIA.

 

I had this code a while back, and found that there was a leak in the exhaust system. That's only one of many things that could cause it, including a bad O2 sensor.

 

What have you done before to fix it? Recent services?

'Lean threashold' makes me think that the ECU is trying to pull fuel out of the mixture to the point where it can't any longer. Leaky fuel injector maybe? Bad MAF? Bad plugs? IDK, just brainstorming here.

 

Have you cleaned the maf during the 2.5 years?
this guy had a bad maf... http://www.renntech.org/forums/index...opic=3834&st=0

 

Thanks everyone. After reading the 3 pages that you referenced redridge, it looks like MAF and the O2 sensors were the culprits for the person with the same error code. I think I'll try that route if I get another CEL code again. Great information from a great forum.

 

Replace the MAF.

My car started generating P1123 codes after interstate highway blasts followed by stops on exit ramps. I'd clear the code and clean the MAF, but a week later after the same trip the code would be back. And then the P1123 code started being accompanied by a P1125 code.

Replaced the MAF, cleared the codes, and no problems.

 

Thanks Doug. You hit the nail on the head with your desription. Where did you order your MAF from?

 

I bought mine from Autopartsworld.com but I believe it is available for a lower price from Autohausaz.com. I've done quite a bit of business with both of those vendors and have always been completely satisfied with them.

BTW, you'll notice the car runs much better with the new MAF.

 

Barn: Clean the MAF with some electronic parts cleaner and also clean your throttle body with some carb cleaner you will be surprised by all the carbon built up in the throttle body.
If this doesn't work THEN buy a new MAF.

 

Thanks Maurice, worth doing before I buy a new MAF.

 

I had this code and tried the cleaning method. CE light would return in a couple of months. Did this for 6 months or so, finally got tired of cleaning and bought new maf from Autohausaz. As Doug mentioned the engine will run much more smoothly with a new maf. Like a new engine. The cleaning may delay the activation of the CE light, but it apparently does not return the maf to proper function, IMO.