7 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHDiagnosing bad MAF vs bad AOS?
Leading reported evidence
Reset code
Performed · outcome unconfirmed
No successful repair reported for this finding.
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0
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1
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Performed · outcome unconfirmed · Original poster
I thought it was just emissions, no big deal, so I reset the code.
Leading evidence: 'Reset code' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Check intake/vacuum leaks' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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Suggestion
Then check the vacuum line run just above your oil dipstick in the pic above as there is a connection under the intake that can come undone.
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Suggestion
Also, disconnect the negative battery terminal to reset the DME so it returns to base default values (as opposed to learned values).
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.
7 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 1 discussions
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Generation: 20261027T035758Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources
Hi all, I have a 2001 911 c4 cab. After sitting for around 3 months for a garage clutch job, and an incident with a loose coolant tank cap, another problem has risen.
First the car was throwing codes P1128 and P1130. I thought it was just emissions, no big deal, so I reset the code. After removing the air box to look at the water pump, the car now has significantly reduced power below 3k RPMs and no power at all at 3-3.5k RPMs. It is also throwing codes P0102 and P1126. MAF is less than 3 years/8k miles old.
The oil filler has what I would consider normal suction while the engine is running and there is a not insignificant amount of oil buildup around where the intake plenum and the throttle body meet.
I�m assuming this means that it is the AOS that failed? It�s had oil around the throttle body for as long as I can remember. The MAF seems clean and fine. Clearing the recent check engine codes made the below 3k RPM problem much much worse. Any good way to be sure?
Throttle body on the right, intake plenum (covered in oil and dirt) in the middle.
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
.
P0102
Mass Air Flow Sensor - Below Lower Limit ...
P1126
Oxygen Sensing Adaptation Area 1 (Cylinders 4 - 6) - Rich Threshold.
I would start by replacing the MAF sensor. The DME is confused by the readings it is getting. Also, disconnect the negative battery terminal to reset the DME so it returns to base default values (as opposed to learned values). Run it and see if the codes come back. To test the AOS you will need a manometer and an oil filter cap that you can mount the fitting to. A lot of good threads on testing the AOS. Use search function.
Check for vacuum leaks. A good place to start would be your aftermarket rubber tube between you MAF and TB as they sometimes don't fit as well as they should. Then check the vacuum line run just above your oil dipstick in the pic above as there is a connection under the intake that can come undone. Then check the oil filler tube for cracks.
Thanks, will do! I don�t think the oil filler tube is leaking. It doesn�t give a whistle sound when the engine is running and the suction is there but not excessive.
