1130 CEL - MAF or AOS?
 

I tripped just the 1130 code about 2 weeks ago. I cleaned the MAF and changed the air filter. I thought all was good until just today it tripped the same 1130 code. So is it likely the MAF needs replacing or is it the AOS?

Thanks in advance for any advice!

many causes possible
 

– Incorrect signal from MAF sensor
– Intake air system leaking
– Fuel pressure too low
– Volume supply of fuel pump too low
– Fuel injectors fouled
– Exhaust system leaking

Here's an update for those of you searching for a solution to your 1130 issues.

I installed a new MAF (from Amazon.com for around $150) and my car hasn't tripped the 1130 code for about a month now. Here's some history that may help you decide what to do. About 2 years ago, I got the first 1130 CEL code. I cleaned the mass air flow sensor, put it back in and it ran fine for about 7 or 8 months. The code tripped again and I repeated the same procedure. This whole process started happening more and more frequently until it started happening about every 5 to 7 days. The car was running rough at idle and my overall gas mileage was slowly getting worse.

Along the way I changed all the spark plugs and the spark plug tubes. I checked the vacuum of the gas cap with the car running to check for possible oil/air separator issues. The cap came off easily and the amount of sucking noise was normal. The issues with the check engine light coming on more frequently should have tipped me off that it was the MAF all along. I'm surprised I got two more years out of the MAF by just cleaning it. BTW, this car has just over 80k miles on it.

IMHO...
If you can clean the MAF and go for many months without the CEL coming on, go for it.
If you easily take off the oil cap, don't start trying to replace your oil/air separator yet.
If the CEL is coming on regularly after you clear it, buy a new MAF. I got a brand new one from Bosch through Amazon for way cheaper than I expected. I paid $166 but I just checked online and the same part is now $248. You may be able to find it cheaper somewhere else.
http://www.amazon.com/gp/product/B001CO317M/ref=oh_o02_s01_i00_details


Hope that helps!

I've had my problem with P1128 and P1130 both coming on while sitting at idle.
There are many threads with P1128/P1130 that I followed to conclude that my MAF was bad.
In those threads, they describe the potential source as MAF or fuel or leak etc will reflect an error CEL for both banks; although the discussion does not negate the possibility of such influencing only one bank, is it possible that MAF replacement is only a temporary cure and not THE SOLUTION?

"...is it possible that MAF replacement is only a temporary cure and not THE SOLUTION?"

If you look at some of the other "1128/1130" threads you'll find people suggesting that it's the AOS but without the symptoms, it's not likely. Issues with fuel pressure or a bad fuel pump usually show up as complete failure and you're stuck on the side of the road.

Mike's listing of possible problems comes right from the Porsche repair manual so it makes sense to take them in order. MAF first, etc. So is it possible for a new MAF not to solve all the problems of tripping a 1128/1130 code? You already know the answer to that.

My posting was to give some direction and support to those who are having issues with these codes. I look to the boards as knowledge base, not as the perfect answer to all my Boxster problems. I could still have one of the other problems on the list and the CEL could trip in another week/month but so far so good.:dance:

And for your sake and mine, I'm hoping I'm right!:D

another good test if you have access to scan data is if the fuel trim is at the lean stop it is usually a mass air flow sensor, if the fuel trim is at the rich stop it is usually the oil separator

clarification to my previous post
 

my statement "...is it possible that MAF replacement is only a temporary cure and not THE SOLUTION?" was directed at symptom where only P1130 was recorded.
By intermixing P1128/P1130 code (as a pair) into this thread, I may have unintentionally diverted the flow of the thread.

Tad

RE: clarification
 

I'm not a 100% certain, but I think the possible faults for 1130 are the same for 1128. And thanks for the clarification!:cheers:

UPDATE!!
One month later, about 5 or 6k miles, and still no CEL.