CEL, MAF... O2 sensor? Oh my.

[TN22Corps]

Background- '96 2wd SR5, 3.4L, 224k mi. Originally had cylinder misfire, corrected with spark plug replacement (and wires while I was at it).

Cleared the CEL and all emissions readiness sensors reset except "catalyst readiness monitor."

Have driven for a week now to and from work 24 mi roundtrip, trying to go through the drive cycle per http://www.watrd.com/work/TSB_EG003-02_(revised).pdf page 12. Go to O'Reillys and OBD II scanner still says "catalyst readiness scanner" not reset.

So, forum and shadetree research suggest clean MAF sensor then think about O2 sensors?

Any similar victims? Advice? Any way to test the MAF sensor to see if it needs replacement and isolate which O2 sensor is defunct? I've read the initial O2 sensor is the first to go..

Thanks, this forum has always proved helpful!

 

[Jayzero911]

I don't know how accurate this is, but I was told by engines instructor (Master Mechanic and NHRA builder/racer) That O2 Sensors don't go bad they just get dirty. If a O2 sensor went out it would more likely be because of a short or something other that its old and went bad. Well for the past 4-5 years when I get any code that comes back even hinting at the O2 Sensors, I take them all out and clean them with carb cleaner or soak them in gas overnight. I have never had to replace a O2 Sensor.

 

[TN22Corps]

Ok sir, worth a try. Anything to save a buck.

Thank you!

 

[Jayzero911]

Ok sir, worth a try. Anything to save a buck.

Thank you!

Just be sure they are dry when you put them back. Had a loud pop or bang once that scarred the sh!* out of me. there was no damage to the car tho lol

 

[TN22Corps]

Update

I cleaned both (before/after cat.) O2 sensors with carb. cleaner yesterday. Going to go through the drive cycle over a couple days, so here's hoping..

 

[TN22Corps]

Update

Well, a friend with a more advanced OBDII scanner was able to help. His showed live O2 sensor voltage with the front reading correctly, 0.1-0.9, and the rear reading 0.

Needless to say, a new O2 sensor is in the mail.

 

[TheDurk]

Well, a friend with a more advanced OBDII scanner was able to help. His showed live O2 sensor voltage with the front reading correctly, 0.1-0.9, and the rear reading 0.

Needless to say, a new O2 sensor is in the mail.

Troubleshooting/diagnostics with the correct equipment. I applaud you, sir.

 

[TN22Corps]

Thank you. There's always time to do it right the first time.