O2 sensor readings

[FSRBIKER]

So my brother plugs in his meter to read any codes I might have stored, I had a constant CEL before I replaced my cats. Now post new cats in the past week I have had a CEL go on for a day than off for a day.

 

He cleared the codes, I had a misfire on all cylinders and a bank one cat effiency code. The thing is my Suby hasn't run this good since I bought it now that I replaced the cats, mileage jumped to 23(from about 18-19)...but my front O2 sensor first read .74V when he plugged the meter in but dropped to .07V and is steady no matter if the car is revved. I am going to see if the CEL comes back on and read the code again but he said I should replace the front O2 sensor anyway. I think I read to always use the OEM part for the front O2 sensor, is this correct?

[nipper]

Yes.

 

nipper

[FSRBIKER]

Nipper shouldn't that front O2 sensor be fluctuating when I give it gas?

[nipper]

It should vary between 0.1 to 0.9 volts once the car is in closed loop mode. Just revving the engine may not be enough to get a variation. There should be some movement, but then again, depsnding upon the sampling rate of the multimeter your using, and weather or not its analog, you may not see it. Hold the engine at the rpm and see if it moves.

 

If your using an analog meter and not seeing the change, it can be a sluggish sensor.

 

When the engine is cold the output will be a steady 0.1-0.2 volts, so at leats we know its warmed up.

 

I am a really big fan (ok i insist upon it) for the front sensor to OE from subaru. They have a differnt response time then Aftermarket (even if they are from the same supplier).

 

nipper

[FSRBIKER]

Thanks, I'll see if it throws a code again first then buy the OEM part. My brother is a Lexus mechanic and has a real good meter, he even had to enter part of my Vin to get the right readings for my car. It's pretty cool to play with and analyze the things going on while your car is running.