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1999 996 OBDii P1121

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6 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW

Discussion summary

YOUR RESEARCH1999 996 OBDii P1121

Leading reported evidence

Replace (originals) i decided

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

Since they have not been changed (originals) I decided to change

1999 996 OBDii P1121
Frequently discussed work

Recommend doing all 4 recently

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 indy also recommended doing all 4 recently after getting CEL code

1999 996 OBDii P1121
Read full discussion summary

Leading evidence: 'Replace (originals) i decided' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Recommend doing all 4 recently' (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.

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1 matching discussions · 6 captured posts examined · 0 partial discussions

Compare 4 other evidence results

Replace four of mine

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

I recently replaced all four of mine.

1999 996 OBDii P1121

Tighten driver side at the factory

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

Whomever tightened the driver side at the factory used gorilla strength...I had to pull hard on that breaker bar just to "break it free"....rest was done by hand.

1999 996 OBDii P1121

Use gorilla strength...i had

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

Whomever tightened the driver side at the factory used gorilla strength...I had to pull hard on that breaker bar just to "break it free"....rest was done by hand.

1999 996 OBDii P1121

Recommend doing all 4 recently

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 indy also recommended doing all 4 recently after getting CEL code

1999 996 OBDii P1121
Frequently discussed actions (7)

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

Recommend doing all 4 recently

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 indy also recommended doing all 4 recently after getting CEL code

1999 996 OBDii P1121

Replace "good one" as well

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

Note: Both O2 sensors did not look bad when removed, however, given that they were original from factory I decided to change the "good one" as well

1999 996 OBDii P1121

Replace (originals) i decided

No successful repair reported for this finding.

0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
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

Since they have not been changed (originals) I decided to change

1999 996 OBDii P1121

Replace four of mine

No successful repair reported for this finding.

0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
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

I recently replaced all four of mine.

1999 996 OBDii P1121

Replace when the first begins

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

Mechanic's philosophy was all the sensors probably went in at the same time (18 years ago) so might as well replace all when the first begins to show signs of a problem.

1999 996 OBDii P1121

Tighten driver side at the factory

No successful repair reported for this finding.

0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
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

Whomever tightened the driver side at the factory used gorilla strength...I had to pull hard on that breaker bar just to "break it free"....rest was done by hand.

1999 996 OBDii P1121

Use gorilla strength...i had

No successful repair reported for this finding.

0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
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

Whomever tightened the driver side at the factory used gorilla strength...I had to pull hard on that breaker bar just to "break it free"....rest was done by hand.

1999 996 OBDii P1121
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.

  • 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: 20261026T181445Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources

POST 1 / ORIGINAL POSTEROriginal post

Got this code while driving last week...based on internet research found to be one of the after cat O2 sensors. Since they have not been changed (originals) I decided to change both: BOSCH13723 for 154.33 total (with shipping and tax) The O2 on the passenger side came out easily with a 22mm wrench, plenty of space for leverage working under the car, and "broke free" relatively easy. The driver side...that is a different story....use a 22mm O2 sensor socket....get a 3/8 18"-24" extension and a breaker bar...working from the top...hope this tip helps someone. If you try from underneath, you may strip it (mine was starting to when I first tried). Whomever tightened the driver side at the factory used gorilla strength...I had to pull hard on that breaker bar just to "break it free"....rest was done by hand. Note: Both O2 sensors did not look bad when removed, however, given that they were original from factory I decided to change the "good one" as well

POST 2Original post

I recently replaced all four of mine. The two on the drivers side were definitely a pain so I ended up spending 5-10 minutes to remove the rear bumper, beam and heat shield to gain more access. Doing this also allowed me to get a torque wrench on all four sensors.

POST 3Original post

My indy also recommended doing all 4 recently after getting CEL code

POST 4 / ORIGINAL POSTEROriginal post

What codes did you get before replacing?

POST 5Original post

P2096 Porsche Fault code 16 - Oxygen sensor ageing Delay bank 1 Part 996.618.660.15

POST 6Original post

Mechanic's philosophy was all the sensors probably went in at the same time (18 years ago) so might as well replace all when the first begins to show signs of a problem. Seemed reasonable advice to me so we did. BTW my car is a 996.2 (03 4s) so the codes may very well be different than on a 99 model.

This is a source reference. Confirm exact model applicability in the original material.