P1128 & P1130 Fault codes advice

[Mike o]

Originally Posted by mikesz

I got my durametric working on my 99 boxster. I got a P1128 & P1130 code which tells me oxygen sensing range 2 cylinder (1-3) and oxygen sensing range 2 cylinder (4-6). should I replace oxygens sensors? car has 77k on it. is replacing oxygen sensors difficult to do for a diy? Can anyone give me advice on how to resolve these issues?

Same thing happens to me a few months ago. I cleaned the MAF and cleared the error codes. Another 50 miles same codes again. Found out it was my AOS failing. I replaced it, cleaned the throttle body and MAF again. Throttle body was really gunked up. Problem solved and car runs better than ever!

[Mike o]

AOS thread


Oxygen sensors usually are not the problem, they are making you aware (warning) that you have a problem somewhere else.
The oil cap removal method is a very good test for AOS failure. If you experience dramatic RPM fluctuations when removing the oil cap, AOS failure is the problem, not the cap o ring.

[kiyakubuke]

this is an old thread but I'll see if anyone is still watching it.

I was getting codes 1126 and 1133. replaced the AOS, oil filler pipe and tube. still ran like crap. replaced the MAF, immediately started running better. cleared the codes thought everything was great.
after about 100 miles CEL came on again. this time with codes 1128 and 1130.
I haven't had time to check the usual suspects yet, but I think I can eliminate the MAF. the old one was obviously bad. not only was there a noticeable difference in how the engine ran, acceleration etc... but my LTFT readings went from 35.1 down to 0 +/- 5.
I know it is possible that the new AOS is also bad. but that would not be my first suspect. I had some difficulty getting the bellow on, so it is possible I torn it. that will be the first thing I check. then I guess a smoke test to check for leaks. I know that fuel delivery can also cause these codes, but I am not seeing any performance issues and acceleration is fine. no hesitation or stumbling.

Anyone else ever seen these codes come up after replacing AOS, MAF?