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check engine light follow-up: Code p1123

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3 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis

THIS DISCUSSION / SOURCE-DERIVED OVERVIEW

Discussion summary

YOUR RESEARCHcheck engine light follow-up: Code p1123

Leading reported evidence

Check oil breather hoses and the oil separator

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
Check the oil breather hoses and the oil separator for a crack or leak.
Original post Read captured discussion
check engine light follow-up: Code p1123

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Leading evidence: 'Check oil breather hoses and the oil separator' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Check oil breather hoses and the oil separator' (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.

Read captured replies

1 matching discussions · 3 captured posts examined · 0 partial discussions

Compare 4 other evidence results

Check vacuum leaks first

Suggestion or failed attempt

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
Moral of the story, check for vacuum leaks first.
Original post Read captured discussion
check engine light follow-up: Code p1123

Replace sensor (or swap the sensor

Suggestion or failed attempt

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 · Original poster
Should we dig deep looking for a leak or replace the sensor (or swap the sensor from the other side as a test) and hope that's the problem?
Original post Read captured discussion
check engine light follow-up: Code p1123

Run condition

Suggestion or failed attempt

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
lean running condition.
Original post Read captured discussion
check engine light follow-up: Code p1123

Test ) and hope

Suggestion or failed attempt

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 · Original poster
Should we dig deep looking for a leak or replace the sensor (or swap the sensor from the other side as a test) and hope that's the problem?
Original post Read captured discussion
check engine light follow-up: Code p1123

Frequently discussed actions (5)

These are separate views of the same evidence. Frequency alone does not establish a fix, and these counts must not be added together.

Check oil breather hoses and the oil separator

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
Check the oil breather hoses and the oil separator for a crack or leak.
Original post Read captured discussion
check engine light follow-up: Code p1123

Check vacuum leaks first

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
Moral of the story, check for vacuum leaks first.
Original post Read captured discussion
check engine light follow-up: Code p1123

Replace sensor (or swap the sensor

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 · Original poster
Should we dig deep looking for a leak or replace the sensor (or swap the sensor from the other side as a test) and hope that's the problem?
Original post Read captured discussion
check engine light follow-up: Code p1123

Run condition

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
lean running condition.
Original post Read captured discussion
check engine light follow-up: Code p1123

Test ) and hope

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 · Original poster
Should we dig deep looking for a leak or replace the sensor (or swap the sensor from the other side as a test) and hope that's the problem?
Original post Read captured discussion
check engine light follow-up: Code p1123

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.

3 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.

Rennlist: 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: 20261026T072535Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources

POST 1 / ORIGINAL POSTEROriginal post

Need advice. Remember, nearest dealer is 500 miles away for me.... Local shop is able to access the on-board diagnostics well enough to obtain the error code p1123 indicating the oxygen sensor as the source of the light coming on. Means cylinders 1,2 &3 are running lean. When he watches the data from the sensor it seems like it's accurate, and may be from a leak letting air in. Or it's a faulty sensor. He's going to do some research and ask I post here for advice (gotta respect that attitude....). Should we dig deep looking for a leak or replace the sensor (or swap the sensor from the other side as a test) and hope that's the problem? Thanks

POST 2Original post

Gary, Check the oil breather hoses and the oil separator for a crack or leak. Mine cracked and threw a CEL but I don't know what the code was. The dealer told me cracked oil separators are a common problem on 996s. Karl

POST 3Original post

My bellow on the oil separator was being sucked in or collapsing at one end during acceleration causing a huge vacuum leak and the error code related to the O2 sensor, i.e. lean running condition. Unfortunately I had already spent the money on new sensors. Mine were probably ok. Moral of the story, check for vacuum leaks first.

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