Bretech

Hi guys the 996 has been pretty good and has no signs of being sick. CEL came on about 2 weeks ago. I replaced plugs and seals, the fuel filter, air filter, cleaned the MAF, Checked for AOS leak via the Oil Cap Test, and added a bottle of Techron about 3 months ago. I run the car on weekends only. I checked for air leaks and tightened the clamps on the intake runners just in case. What could be throwing these 2 codes. Mind you the it pops up after 60 miles of driving. If anyone could help I thank thee

Macster

AOS certainly comes to mind. The codes indicate the DME is at its enrichment limit. That's a strong sign of an intake air leak.

Keep that in mind.

But consider this too: My 02 Boxster generated at least one error code related to running too lean more than a few times. I finally decided it was the MAF.

Then the error code or codes came back. A co-worker with me at the car while the engine was idling and the rear trunk lid open heard an air leak that turned out to the oil tube filler cap. The MAF was fine. When the replacement MAF finally quit I installed the old/original MAF and it is still going strong.

Anyhow, at idle/low speed the leak represented a big leak. But at higher engine speeds not so much.

As a result the CEL and code would only show up after some driving, generally after 30 miles (my work commute) as I was driving nice and easy through town after 28+ miles of freeway driving.

Bretech

Thanks! Gonna look at the oil filler tube sometime over the weekend. other than that, how can i check the aos bellows?

Macster

The bellows or hose that connects the AOS to the engine you can inspect with I suspect some difficultly.

The AOS diaphragm you can't check directly. Some have reported checking engine vacuum at idle and if it is out of spec -- I do not what this is -- the AOS is considered bad.

The AOS may be going bad but you may not be able to detect this for some time.

The 2nd AOS on my Boxster failed upon cold start one day at a motel parking lot but this was after a 3 day slog of over 2K miles. All the AOS (as it turned out) would do is trigger a CEL generally at the end of the day's drive (hundreds of miles at highway speeds) as I was coming off the freeway followed by sitting at a stop light on my way to a hotel for the night.

The behavior (when the CEL came on and the error codes -- which I can't recall now) had me thinking MAF and I decided to push on thinking if the MAF failed I could disconnect it or buy an OE or EOM replacement on the road.

Was not the MAF as it turned out.

So the bad AOS was sort of ok until it obviously was not ok. That cold start had the old oil smoke just billowing from the exhaust and I knew. I just knew what was wrong.

Hurdigurdiman

about 3 months ago I got a CEL. I needed a job on the gearbox and a pre maintenance AOS as well so I had an INDI do it. Then I told him about the CEL which has never been cured so far. After about 60 miles of normal driving under 3000 revs I got the po1124 and po1126 when stopped idling at a red light this morning AGAIN. At that time it was idling at 800revs or slightly under.Never had white smoke. Car runs great. Since the Aos job, I replaced the MAFS exact same Bosche. I or should I say, WE, have been getting a CEL for months. Work done so far Carbon filter shut off valve, also the double valve at top of carbon canister next to gas tank locking door. He changed a large unit on top of the gas tank under the battery after a smoke test. New same oil filler cap. I am running out of ideas. Another smoke test may be in order. What dyu all think?

Hurdigurdiman

I just got the same P1124 and P1126 via my OBD11 scanner but no CEL. I am expecting the CEL to come on AGAIN in the near future. HEEEELP anyone.

OK the CEL is back.

I found a split in AOS lower accordion boot and replaced the boot. Also a broken wire strand on the gas cable behind the throttle. (1999 has the gas cable. Not egas). The accelerator cable hangs up just short of closing which throws the short term fuel trim into convulsions because of broken strand. So I think the 1124 and 1126 codes are caused by a small leak or broken strand or combination of both. The small vacuum leak only contributes to 1% of the air intake at speed. At idle it contributes to 25% and throws the STF trim for a loop and the 2 codes and CEL up at idle. BTW I am awaiting delivery of a new Gas Cable.