Intermittent Oxy Sensor fault (1 Viewer)

[sjpitts]

Back in July I had the check engine light come on-- 93 FJZ80 with 125k miles. It was a code 28, indicating a bad oxygen sensor.

I took an ohm meter to the sensor, and it measured within range.

I pulled the fuse to reset the ECM, and the check engine light went off. It stayed off for a month or so until I was taking a road trip -- pulling a small trailer up to the mountains. The check engine light went on when pulling up a pretty good sized hill. Again, the code was 28 and I reset it.

Now several months later I was taking another road trip, and again the check engine light went on -- again while climbing a mountain on the highway. This time I never got around to clearing the code, but it appears to have cleared itself.

When it first happened I talked to cruiserdan about this, and he said just to replace both sensors-- they are probably original ---and should be replaced every 100k at a miniumum anyway.

I have decided to do this, but the intermittent nature of the fault gives me some pause. Is there any chance that there is another problem causing this fault-- like perhaps a clogged cat?

Jared

 

[PHAEDRUS]

not likely.
mine has been going off every once in a while for about 3 months now. clear the code and I am fine. It only trips when I am at pretty steady low rpms. like cruising at 50 mph it will trip. reset it and its fine for a few more weeks. I need to get some new ones and just put them in but $$ is tight till after christmas. Dave

 

[Arya Ebrahimi]

Just went through this on mine. Does the cruiser have a sporadic idle at times or otherwise hesitate under acceleration? Is it overly sluggish and underpowered? Mine was, and after I replaced the O2's it's like a completely different truck. BTW, I replaced mine because mine also threw the 28 code. See sig for my year and mileage.

Ary

 

[landtank]

I had a CEL for O2 sensor #2. SInce I was at 116k I did the 120k Tuneup and now at 150k am still CEL free. I'd do the full tuneup, fuel filter, TB cleaning and see if things clear up.

 

[loquito]

(Is there any chance that there is another problem causing this fault-- like perhaps a clogged cat? )

I can not answer for a Toy but on the ford when we put in a new motor, the mechanic
hooked up a preasure guage in the bung for the O2 sensor. He stated that when your cat is failing it reads excess preasure which can lead to overheating. Don't know for sure as I am only 1 capable.
S

 

[robbie]

On the early cruisers this is a good indication that the O2 sensor is bad. It may measure ok on the meter but not be responding with in the parameters set in the computer at certain times. The later models Like ricks is different in the way the O2 stuff is handled. I personally would change the O2 sensors and be trouble free for 100k miles or so. It is very rare for the cat to be messed up, if back pressure at the cat is happening you would also see loss of power under hard accleration, if really bad no power to be had unless really light throttle. If you have not done a tune up then you will need to do a tune up for the truck to run at it best. latter robbie

 

[cruiserman]

My '93 does the same. I've reset it twice now this year. Passed emissions with no problems. Can I expect better performance with new sensors or just no code?

 

[cruiserdan]

You can expect the ECM to get more accurate information about what is going on. That may or may not make a difference in performance depending upon how bad it is in the first place.

Logic dictates that if the ECM has a true picture of O2 content it can do a better job of fuel metering.