O2 Sensor (s) Question

[PRO 5]

I just have a couple questions about the O2 sensors after you go F/I. Do you reuse both of the O2 sensors? I know that you put one back on the down pipe but where would you put the other one? I will be eliminating both of my cats. Would I just put the other sensor down stream from the first one? Just need to know cause I don't want my check engine light to come on! Thanks!

Dave

 

[Stou]

I installed my second O2 sensor on the front part of my exhaust pipe. I tried to make it work with some resistor/capacitor to avoid CEL but with no succes. It work for a day or two and the CEL came back.

So the 2nd O2 sensor is there but the ECU is always receiving to much O2 signal and the CEL is always on....... so I removed the CEL light!!!

 

[Keith@FP]

The purpose of the second O2 sensor is to confirm that the cat is working. If the cat's not there, it's obviously not working. The second O2 sensor will tell the ECU this, and hello CEL.

The ECU in the Protege is one smart little cookie. It's not uncommon for a modern ECU to fire off one rich pulse to check the O2 sensors, so installing a voltage clamp will trigger a different CEL code.

Keith

 

[PRO 5]

I have one more question about the O2 sensor. There are 4 wires on the O2 sensor. Blue, White, and 2 Black wires. Which wire is the output wire? Thanks.

Dave

 

[Stou]

It's the blue one.

 

[PRO 5]

Thanks Stou!

Dave

 

[chdesign]

I got one for you.....put my O2's back in stock location with a good cat and still got a cat not effective code. Its my MAF not reading correctly that is throwing it says a mazda tech here that when the turbo was on ti it pulled too much air than what the MAF was designed for and miss calibrated it but who really knows.

 

[blynzoo]

I got one for you.....put my O2's back in stock location with a good cat and still got a cat not effective code. Its my MAF not reading correctly that is throwing it says a mazda tech here that when the turbo was on ti it pulled too much air than what the MAF was designed for and miss calibrated it but who really knows.

It's possible, I'd just go the trusty old "reset the ECU." Unplug the negative, pump the brakes about 10 times, and hook it back up, the ECU should re-test.