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O2 Sensor Replacement After Rebuild

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YOUR RESEARCHO2 Sensor Replacement After Rebuild

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Replace but 2 must be

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Suggestion · Original poster

I remember reading somewhere that all 4 should be replaced but 2 must be replaced.

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O2 Sensor Replacement After Rebuild
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Leading evidence: 'Replace but 2 must be' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Replace but 2 must be' (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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Replace but 2 must be

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Suggestion · Original poster

I remember reading somewhere that all 4 should be replaced but 2 must be replaced.

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O2 Sensor Replacement After Rebuild
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8 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.

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POST 1 / ORIGINAL POSTEROriginal post

Back when I ordered all the parts for a rebuild (a year ago) I bought 2 O2 sensors. I remember reading somewhere that all 4 should be replaced but 2 must be replaced. What I don�t remember is if it�s the pre cat or post cat that must be replaced. Anyone have any idea what I�m talking about? I�ve searched and can�t seem to find it. thanks in advance

POST 2Original post

Front O2's monitor AFR and provide feedback to the ECM telling the car to add or subtract fuel Rear O2's monitor catalytic converter performance they do not determine fueling with the exception of COT which in many cars will signal the ECM to dump fuel into the cylinders to cool the cats. jmo

POST 3 / ORIGINAL POSTEROriginal post

Quotes source post: 18605681

so it must be the front that need replacing. If I�m understanding what you�re saying correctly.

POST 4Original post

If the rear were operating poorly wouldn�t you expect to see a CEL or is that not always the case?

POST 5Original post

Quotes source post: 18606542

if any of the 4 were operating out of there range they would through a code. If the front 2(closest to header) r operating pourly it can effect the fueling which is bad. So yes get new front o2s.

POST 6Original post

Quotes source post: 18605683

Correct,the front/pre cat o2 are what help control the afr. But with the relatively inexpensive o2 sensors cost why not do all 4 at the same time you're down there and avoid the possible annoying mil on your dash cluster... Also good to start with all fresh o2's after a (15k$?) engine rebuild. jmo

POST 7Original post

what do ppl rec for replacements - oem (bosch) ok or is the extra $ of oem warranted?

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