Nitto Mid-Pipe Check Engine Light fix

[ROCKLAND TOYOTA]

Originally Posted by largeorangefont

Rockland,

Your ECU is not scouring the internet looking for proof that you have screwed with it.. and throwing CELs when you wake up in the morning.

What you fail to realize is how an ECU works. ECUs operate on voltage signals from sensors. When voltage is out of an acceptable range on a given sensor for a certain amount of time, an CEL is given (or worse, it depends on the sensor).

By wiring in a resistor to give the ECU a different voltage reading, or by mounting the o2 sensor out of the stream of exhaust you change the voltage sent to the ECU. If the "new" signal is within accepted limits, a CEL is never thrown. These limits don't change, and the ECU does no "learning" for the rear o2 sensor.

If you don't throw a CEL in the first couple days, or couple hundred miles, you will probably never see one for cat ineffiecicy. These types of CELS are not thrown right away because cats are less effective when cold, and the ECU is programmed to account for that. Again, no "learning" involved.

good explanation but i never said the wiring method was bad. just the fouler