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Re: Using the O2 Sensor to Diagnose Lean or Rich Cylinders
Posted to Technical Theory Forum on 2/1/2018 3 Replies

A Denso instructor at a class a few years ago said;

1. Both spark and ign, misfires will show up as lean on the front O2. 2. Only a fuel misfire will show up as lean on the rear O2.

There's various logic/reasoning to this. The cat acts like a second combust... Login to read more.

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