6 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHError code P1128, endless hole of error codes - 986 Forum - The Community for Porsche Boxster & Cayman Owners
Leading reported evidence
Replace before
Performed · outcome unconfirmed
No successful repair reported for this finding.
0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that performed work without a confirmed outcome
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Performed · outcome unconfirmed · Original poster
I have previously had issues with P0410 and P1411 before this and had my air filter replaced before that.
Error code P1128, endless hole of error codes - 986 Forum - The Community for Porsche Boxster & Cayman Owners
Frequently discussed work
Check sensors...everything
No successful repair reported for this finding.
0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
Discussions that contain suggestions
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Suggestion
My CEL came on on June 21, 2025 and I schedule a diagnostic appointment...the shop did a smoke test and checked sensors...everything checked out but the light and error codes came back...I brought it back and they checked again (another smoke test)...there were no obvious vacuum leaks from what they could tell.
Error code P1128, endless hole of error codes - 986 Forum - The Community for Porsche Boxster & Cayman Owners
Read full discussion summary
Leading evidence: 'Replace before' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Check sensors...everything' (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.
Source reports, not a diagnosis or a success probability. Counts refer to discussions and can overlap.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that contain suggestions
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Suggestion
My CEL came on on June 21, 2025 and I schedule a diagnostic appointment...the shop did a smoke test and checked sensors...everything checked out but the light and error codes came back...I brought it back and they checked again (another smoke test)...there were no obvious vacuum leaks from what they could tell.
Error code P1128, endless hole of error codes - 986 Forum - The Community for Porsche Boxster & Cayman Owners
Inspect inside...it is starting
Suggestion or failed attempt
No successful repair reported for this finding.
0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that contain suggestions
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Suggestion
The next step would be to take the intake manifolds off and inspect inside...it is starting to get a little costly and I would like to get to the bottom of it.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that contain suggestions
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Error code P1128, endless hole of error codes - 986 Forum - The Community for Porsche Boxster & Cayman Owners
Smoke-test )...there were no obvious vacuum leaks
Suggestion or failed attempt
No successful repair reported for this finding.
0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that contain suggestions
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Suggestion
My CEL came on on June 21, 2025 and I schedule a diagnostic appointment...the shop did a smoke test and checked sensors...everything checked out but the light and error codes came back...I brought it back and they checked again (another smoke test)...there were no obvious vacuum leaks from what they could tell.
Error code P1128, endless hole of error codes - 986 Forum - The Community for Porsche Boxster & Cayman Owners
Frequently discussed actions (6)
These are separate views of the same evidence. Frequency alone does not establish a fix, and these counts must not be added together.
Check sensors...everything
No successful repair reported for this finding.
0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
Discussions that contain suggestions
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Suggestion
My CEL came on on June 21, 2025 and I schedule a diagnostic appointment...the shop did a smoke test and checked sensors...everything checked out but the light and error codes came back...I brought it back and they checked again (another smoke test)...there were no obvious vacuum leaks from what they could tell.
Error code P1128, endless hole of error codes - 986 Forum - The Community for Porsche Boxster & Cayman Owners
Inspect inside...it is starting
No successful repair reported for this finding.
0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
Discussions that contain suggestions
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Suggestion
The next step would be to take the intake manifolds off and inspect inside...it is starting to get a little costly and I would like to get to the bottom of it.
Error code P1128, endless hole of error codes - 986 Forum - The Community for Porsche Boxster & Cayman Owners
Smoke-test )...there were no obvious vacuum leaks
No successful repair reported for this finding.
0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
Discussions that contain suggestions
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Suggestion
My CEL came on on June 21, 2025 and I schedule a diagnostic appointment...the shop did a smoke test and checked sensors...everything checked out but the light and error codes came back...I brought it back and they checked again (another smoke test)...there were no obvious vacuum leaks from what they could tell.
Error code P1128, endless hole of error codes - 986 Forum - The Community for Porsche Boxster & Cayman Owners
Coverage and how to read this overview
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.
6 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
986Forum: 1 discussions
0 evidence records excluded for query context · 0 excluded by outcome qualification · 0 adjusted by outcome qualification.
0 acknowledgements have no verified action link; they do not establish a repair result.
Generation: 20261027T070717Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources
So recently I had my 2002 986 in the shop for an AOS replacement and I immediately got the P1128 error code. I have previously had issues with P0410 and P1411 before this and had my air filter replaced before that. There have been a few other unrelated (I think) times it has been in the shop for maintenance and it's starting to burn a hole through the wallet. I need the car to not have any error codes In order to pass inspection, and I don't feel like paying the labor fee for letting someone else do it anymore. any idea on where I should go from here?
Let me know if there is any other Info/pictures you might need to diagnose this.
P1128 - Fuel air mix so rich the system cannot adjust
-Incorrect MAF signal
-Fuel pressure too high
-Leaking injector
-EVAP cannister purge valve stuck open
P0410 SAI signal implausible
-Wiring harness issues
-SAI pump
-Changeover valve
-Air supply lines
P1411 SAI below limit
I have having a similar issue with these error codes (2002 Porsche Boxster S, 42,000 miles). The check engine light is on and I had a reputable shop look into it twice. My CEL came on on June 21, 2025 and I schedule a diagnostic appointment...the shop did a smoke test and checked sensors...everything checked out but the light and error codes came back...I brought it back and they checked again (another smoke test)...there were no obvious vacuum leaks from what they could tell. The next step would be to take the intake manifolds off and inspect inside...it is starting to get a little costly and I would like to get to the bottom of it.
The car drives fine and I have not noticed anything.
Mike in Virginia
Final update: after going down many rabbit holes, I decided to just go and take the whole manifold off. Upon doing so, I discovered that a wire had been pinched between the header and the manifold gaskets on the side showing the code. I have no clue how it got there but after replacing the gasket and moving the wire out the way, the error code disappeared. Stupid reason, but hilariously simple to fix.
Thanks for reporting back. Number 4 in this chart mentions "Intake air system leaking" so you choose the right work
https://charm.li/Porsche/2000/Boxster%20%28986%29%20F6-2.7L/Repair%20and%20Diagnosis/A%20L%20L%20%20Diagnostic%20Trouble%20Codes%20%28% 20DTC%20%29/Testing%20and%20Inspection/P%20Code%20Charts/P1128/DME%207.8/Oxygen%20Sensing%20Adaptation%2C%20Idle%20Range%2C %20Bank%201%20-%20Above%20Limit/
This is a source reference. Confirm exact model applicability in the original material.
