rear O2 sensor
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From: San Antonio, Texas
The downstream O2 sensors produce a voltage output in the same way the upstream do. They can tell if the cat is plugged. If a cat is sufficiently plugged to effect efficiency of the "fore-aft oxygen sensor control routine" programmed into the PCM, it will produce a P2096 or P0420 Code. The PCM constantly monitors the time it takes the downstream O2 sensors to detect the PCM's intentionally created conditions of over rich and return to normal when the mixture is leaned out. This test fails when correction value is greater than a factory calibrated limit.
You likely would experience other symptoms (such as misfires, loss of power or fuel mileage), first or other codes before the catalyst's efficiency codes.
A short (although very noisy) drive with the front O2 sensors removed will prove/disprove a clogged cat. You would have a noticeable improvement in responsiveness if plugged.
You likely would experience other symptoms (such as misfires, loss of power or fuel mileage), first or other codes before the catalyst's efficiency codes.
A short (although very noisy) drive with the front O2 sensors removed will prove/disprove a clogged cat. You would have a noticeable improvement in responsiveness if plugged.
Hotshot
Joined: Jan 2004
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From: St Louis
Exhaust.
No, not really. If the cat is plugged, you'll have other far more serious driveability symptoms that should spur you to action before you ever get an efficiency code. They're there to determine if the catalyst is functional in terms of doing its actual job.
can they tell you if cat. is plugged?
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From: San Antonio, Texas
@bjwilli22
It sounds like @projectSHO89 and I gave opposite answers to your question. But I think we are both saying the same thing. I do AGREE with @projectSHO89 that "you'll have other far more serious driveability symptoms first". Perhaps I should have emphasized my point about "experiencing other symptoms" stronger.
What specific symptoms are you experiencing?
It sounds like @projectSHO89 and I gave opposite answers to your question. But I think we are both saying the same thing. I do AGREE with @projectSHO89 that "you'll have other far more serious driveability symptoms first". Perhaps I should have emphasized my point about "experiencing other symptoms" stronger.
What specific symptoms are you experiencing?
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