O2 Sensor Incomplete....wtf?

[TheDurk]

Ok, I'm stumped. My truck is running well, no codes showing or stored, running in closed loop, all other tests are complete, including catalyst, but it shows Incomplete for O2 Sensor. I can reset, and it goes back the same. I leave it a month, and it won't complete and it won't fail and set a code.

I'm pretty sure NJ will pass me this way (due in June), so I'm leaning toward ignoring it. But part of me wants to fix it. In all my time here, I've never seen anything like it reported.

Anybody have any ideas? Other than a new ECM. Not doing that unless there is a reason to.

Oh, I had codes on my A/F and swapped it before this started. New Denso. Rear O2 has about 90k.

 

[Konkordmusk]

I have once solved this exact issue on a 1st gen tundra... It ended up having a weak battery and weak charge, but enough to where it would start and run fine.

 

[19963.4lsr5]

Have you gone on a long highway drive yet?


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[TheDurk]

Have you gone on a long highway drive yet?


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Several 100 mile plus.

 

[19963.4lsr5]

That sucks. When I bought the 97 limited in north Philadelphia it took 90 miles of the 110mile trip on the PA turnpike to set either the Cat or O2 readiness monitor. I forget which one (2years later) but I did replace the front O2 sensor with a correct one instead of the universal screw in sensor with adapter plate. So I think it was the Sensor. Not Cat


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[St Runner]

I would say ecu. Anything with the sensor itself would throw a code. I would keep an eye for a used one at a good price (never hurts to have a backup) or find someone locally you can swap with just to see if it clears. Mostly I am fascinated to see if anyone has more knowledge than you and knows the answer.

 

[StreetCreeper]

Oh shit — you know it's bad when TheDurk is stumped on something electrical!

 

[nissanh]

^^^^ Exactly.
If you need an ECU just to check it is the cause, let me know I have an extra 5vzfe A/T ECU which I can let you borrow.

 

[TheDurk]

^^^^ Exactly.
If you need an ECU just to check it is the cause, let me know I have an extra 5vzfe A/T ECU which I can let you borrow.

Thanks, but I'm a Cali. 5-speed--sort of rare.

I see no reason not to leave it as is, since I seem to have 100% functionality. The ECM is successfully using both sensors, even if it can't complete the test, so why should I care? This last being a question just as important as "how do I fix it?"

 

[LittleCaesar]

So you get live data from the sensors but they just don't complete the test?

I have to ask if this was occurring before the frame swap.