Planet-9

Downstream O2 sensors - are they needed even with a tune?

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YOUR RESEARCHDownstream O2 sensors - are they needed even with a tune?

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Disconnect sensor

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Suggestion
I'd rather completely disconnect the sensor from the harness rather than just having it hang out in open air but I'm having reports that if you physically disconnect the sensor from the harness, that there is no way to "tune out" the check engine light with flashes such as the
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Downstream O2 sensors - are they needed even with a tune?

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Leading evidence: 'Disconnect sensor' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Disconnect sensor' (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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Run with catless

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Suggestion
to run with catless
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Downstream O2 sensors - are they needed even with a tune?

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Disconnect sensor

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Suggestion
I'd rather completely disconnect the sensor from the harness rather than just having it hang out in open air but I'm having reports that if you physically disconnect the sensor from the harness, that there is no way to "tune out" the check engine light with flashes such as the
Original post Read captured discussion
Downstream O2 sensors - are they needed even with a tune?

Run with catless

No successful repair reported for this finding.

0
Reported fixes: 0
Unsuccessful attempts: 1
Discussions

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Discussions that contain suggestions: 1

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Suggestion
to run with catless
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Downstream O2 sensors - are they needed even with a tune?

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Generation: 20261027T000231Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources

POST 1Original post

Hi guys, hoping someone can shed some light on an issue that I cannot get any real solid answers on. I'm wanting to get the Cargraphic race headers for my 987.2 CS but they have an interesting quirk in that they do not have a bung for the secondary (downstream) O2 sensors . I'd rather completely disconnect the sensor from the harness rather than just having it hang out in open air but I'm having reports that if you physically disconnect the sensor from the harness, that there is no way to "tune out" the check engine light with flashes such as the Cobb AP and Softronic . Is this true? I've also been hearing that the secondary O2 sensors do play a minor role in A/F determination in the 987.2s, again, any truth to this? I thought the downstreams were for cat efficiency monitoring only! I would really appreciate any insight! Thanks!

POST 2Original post

Call Scott at Softronic . On the Gen 1's I had to leave them plugged into the harness to keep the CEL from coming on, but they were not plugged into my exhaust system at all as I don't have secondary o2 bungs either. I'm fairly certain they do not play a role in the gen2's, but that's from memory. Again, a quick call to Scott will net you a definitive answer....

POST 3Original post

Gen 2 definitely needs both pre and post cats even with a tune. I have a softronic tune to run with catless headers and recently I switched over to a full race system from Lucas fab which had only one o2 bung on each side. Initially for couple miles CEL wasn't triggered but eventually the car threw a CEL and started misfiring badly. I contacted Scott and he varified that both pre and post cats are required.

POST 4Original post

I'm not following you here. When you say cats do you mean o2 sensors and what do you mean pre and post? Upstream and downstream?

POST 5Original post

I do not have them as I do not have cats. Tuned out with no CEL by Evomsit in my RS370 tune. Works great with no issues.

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