Help with my CEL code

[Rated-S]

My 01 Boxster S has been throwing a P1126 code for about 6 months now. I know this means that cylinders 4,5,6 are running lean and the DME has richened that side up as far as it can. I thought it was a bad AOS but I replaced it yesterday and took it for a drive and the CEL came back on again. I also noticed when I had the engine cover off and started it that there is a slight air sucking sound as soon as you crack the throttle open. Does every Boxster make that noise? Or should I be looking for a vacuum leak? If it's a vacuum leak where should I start my search?

[Loren]

Please doa search for P1126 - this has been covered many many times.

[Rated-S]

I did a search on P1126 well before I made this thread. What I don't get is everyone who is getting P1126 is also getting other codes with it and it's usually a MAF they replace and it's fixed. I can't find a single other person who is only getting the P1126 code and nothing else.

[Loren]

P1126 Oxygen Sensing Adaptation, Lower Load Range, Bank 1 – Above Limit

Possible causes:

– Incorrect signal from MAF sensor

– Intake air system leaking

– Fuel pressure too low

– Volume supply of fuel pump too low

– Fuel injectors fouled

Look for leaks and try cleaning and/or replacing your MAF.

[Rated-S]

P1126 Oxygen Sensing Adaptation, Lower Load Range, Bank 1 – Above Limit

Possible causes:

– Incorrect signal from MAF sensor

– Intake air system leaking

– Fuel pressure too low

– Volume supply of fuel pump too low

– Fuel injectors fouled

Look for leaks and try cleaning and/or replacing your MAF.

Got that much but do you think a MAF would only throw one side out of whack?

[Loren]

Without seeing the MAF air flow readings at idle and 2500 RPM - you do not know that it is good. Perhaps the other bank just hasn't faulted yet.

[Rated-S]

Ok I'm going to go try one more time to see if I have a vacuum leak and then I guess I will be ordering a new MAF.

[ericinboca]

Ok I'm going to go try one more time to see if I have a vacuum leak and then I guess I will be ordering a new MAF.

The big tubes that cross the motor from one air distributor to the other - the ones clamped on with the rubber collar boots - they are a frequent cause of vacuum leaks. You need to get your hands in there and press on the edges of the collars to be sure it is placed far enough on the tube on one side and the air distributor on the other. The may look like they are on right, but if you press them and they are not, the edge will collapse some showing you where it is off. Doesn't take much of a leak. Be sure you get your hands underneath them too.

Hope that helps.

[Rated-S]

Yeah I just finished checking everything. I tightened every clamp and sprayed two cans of carb cleaner around to see if the engine RPM would change and nothing. I swear I hear a Vac leak but I tried every spot there is and nothing. And to top it off while I was under the car looking around I noticed my RMS is leaking :rolleyes: 22,000 miles and this car has had a Wheel bearing, CEL, CV boots and now an RMS.

[ericinboca]

Yeah I just finished checking everything. I tightened every clamp and sprayed two cans of carb cleaner around to see if the engine RPM would change and nothing. I swear I hear a Vac leak but I tried every spot there is and nothing. And to top it off while I was under the car looking around I noticed my RMS is leaking :rolleyes: 22,000 miles and this car has had a Wheel bearing, CEL, CV boots and now an RMS.

Wow, that's tough luck. I go through wheel bearings fast - especially the left front on my track car - at least have to replace it once a year, but the track use explains it. Boots can deteriorate in time, especially if something like a brake cleaner got on it somehow along the way. RMS leak just bites. No good explanation for that.