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THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHMy AOS failure symptoms - please take a look
Reported repair
Replace $20 aos bellows
Reported resolution
1
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0
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1
Discussions
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Leading evidence: 'Replace $20 aos bellows' (1 discussions report resolution; 0 report an unsuccessful attempt). Across 1 matching discussions, The most frequently discussed action is 'Replace $20 aos bellows' (1 discussions). For that action, 1 discussions report a resolution and 0 report an unsuccessful attempt. The most frequently reported fix is 'Replace $20 aos bellows', supported by resolution reports in 1 discussions. These are forum reports and suggestions, not a confirmed diagnosis.
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Reported fix
Last summer I replaced the MAF. So a few weeks ago I changed the spark plugs, coil packs and AOS and now no more codes.
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Performed · outcome unconfirmed
– 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 Likely causes are air leaks - like AOS, AOS bellows, oil filler cap, or disconnected /loose intake hoses.
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Suggestion
Check all of the vacuum lines and might as well replace the oil filler tube while in there.
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Performed · outcome unconfirmed
– 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 Likely causes are air leaks - like AOS, AOS bellows, oil filler cap, or disconnected /loose intake hoses.
Counts describe captured discussions, not unique people or a diagnosis. Author identities are not reliably stored. Exact duplicate evidence is counted once across matching discussions; one discussion counts at most once per action/state. Multiple repairs reported together remain a combination. Suggestions and failed attempts do not establish a fix. Matches cover whole discussions and can include related faults, model variants and incomplete threads.
14 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 1 discussions
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Generation: 20261026T124918Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources
Hi all!
Some background on the car, 2001 C2, 87k, just got it two weeks ago, and suposedly in only did 7000miles since 2009, so it was sitting somewhere for long time I guess
So here is the list of symptoms :
P1128 + P1130, LongTerm Fuel Trims are at -17%
Extremely hard to startup, have to crank for 20 seconds and it gets worse everyday
Oil Filler Cup off - good suction can be heard, but cap does come out. Blocking with my hand does change the idle
Thanks
From Loren at RennTech
Covered many many times here... – 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 Likely causes are air leaks - like AOS, AOS bellows, oil filler cap, or disconnected /loose intake hoses. Could also be a bad MAF but that is easy to check with Durametric - just look at the MAF voltage at idle and see if it increases with RPM. If it doesn't then it is bad.
First things first - clean or replace the MAF sensor.
p1128 corresponds to: "Long Term Fuel Trim B1 System Too Lean" which means that the car thinks it's running leaner than it should be.
p1130 corresponds to: "Air/Fuel Sensor Circuit Range/Performance (Bank 1 Sensor 1)" which basically means the same as the p1128.
Then run a tank of fuel with some Techron in it.
^^^^^ This.
If you are replacing the starter, and the AOS, all sorts of these things need to be taken out. Why not clean the MAF sensor? And the TB, ICV at the same time. Check all of the vacuum lines and might as well replace the oil filler tube while in there.
I had the identical pcodes a few weeks ago along with smoke from the exhaust and it was hard to remove the oil filler cap. Last summer I replaced the MAF.
So a few weeks ago I changed the spark plugs, coil packs and AOS and now no more codes. I'm at 160,000 km.
Had the same codes on my '99 Boxster. Usually some sort of vacuum leak. Particularly if the car has been sitting outside, the plastics can just dry rot.
My AOS bellows was dry-rotted and cracked.
A $20 AOS bellows replacement fixed the issue.
I would plug a smoke machine in before you just start replacing parts ***** nilly.
Sounds like a MAF, or the MAF and AOS are failing simultaneously. Hard starting also comes from one of the camshaft hall effect sensors failing, as the engine's "fast start" is not active with only one sensor being read.
Lots of times there are no fault codes of this.
