22 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHO2 sensors
Leading reported evidence
Use on my '99
Performed · outcome unconfirmed
No successful repair reported for this finding.
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1
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Read evidence and context
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Leading evidence: 'Use on my '99' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Replace 4 as they do age and get lazy' (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
It would be a good idea to replace all 4 as they do age and get lazy.
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Suggestion · Original poster
I am changing my whole exhaust system, headers, mufflers, catalytic converter.
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Suggestion
NTK / NGK sensors - they run longer than normal wire length.
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Suggestion · Original poster
Just curious gentlemen, what was the last year 996 that used just upstream (before not after) cat sensors?
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.
22 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 1 discussions
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Generation: 20261027T084359Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources
I have a 2001 996 C2. I am changing my whole exhaust system, headers, mufflers, catalytic converter. My question is do I need new O2 sensors? If so, do I need 2 or 4? One before and after the cat, or just the pre cat for each side/converter...thanks.
There are 4 units - 2 upstream and 2 downstream (all same sensor)
You don't need new sensors but it may be wise as they are very cheap (under $250 for all 4 units) and it makes sure there are no issues down the road. Easy access now and makes sense given the rest of the spend.
https://www.rockauto.com/en/catalog/...2)+sensor,5132
There are coupons for 5% off - look it up in google.
The 2 upstream and the 2 downstream r the same, all 4 r NOT the same. It would be a good idea to replace all 4 as they do age and get lazy. I perfer the bosch units for the 996.
NGK - lists 1 sensor for all position
Bosch - lists the same probe.... The difference lies in the length of the wire - upstream is 22" and 20.5" for downstream.
NTK / NGK sensors - they run longer than normal wire length. Perhaps use it on other models as well.
Bosch - probes are the same
https://www.boschautoparts.com/produ...eTypeGroupId=2
Just curious gentlemen, what was the last year 996 that used just upstream (before not after) cat sensors? I'm guessing it's when they switched from cable to drive by wire throttle body correct.
My answer was wrong acc. to an earlier post, the upstream ones have longer wires that's why I deleted it. Sorry for the confusion...
Soldering is not the way to do it but BOSCH also provides the correct type of sensor with pigtail but without the connector as a generic offering. You remove the connector from your old sensor by cutting it off and connecting it to the pigtail by means of included crimp connectors and heat shrink tubing.
Getting 4 sensors with the long wires you can swap position as you like :-) (that's how NGK manages 1 p/n for all 4sensors)
ThePrf is not going to agree but all of the 4 sensors are narrow Band sensors.
BTW, did you read post #7? Everything you need to know to find out what the differences are between the two part numbers.
If they are all 4 pinners then they are narrowband - which is fascinating, as every OBD2 car I have ever owned has wideband front O2's. Even my '96 Passat...
This is a source reference. Confirm exact model applicability in the original material.
