When an Evo throws a cel because of an o2 sensor, will it run in any sort of "safe mode"? In other words, does it revert to another map with safer timing fuel etc. when certain conditions occur such as a bad 02 sensor. My friend currently has a cel because of his testpipe. This question crossed my Mazda did this for certain codes, including the o2 sensor codes.

 

NO!

The rear O2 sensor is used only for the catalyst efficiency test.

A bad front O2 sensor will cause the car to run in open-loop, and possibly in the low octane maps which are a less aggressive (bad gas) tune. But this doesn't apply to your question.

There is no real "Safe Mode" as the low octane maps are really the safe mode on the Evo.

 

Thank you sir, you have totally answered my question . Cel fix this weekend and my friends car will be good to go.

 

yeah and quite a few people copy the high octane maps to the low even though they have knock