2000 Chevy 3500 Oxygen Sensor Error

[lynch763]

My folks have an older Minnie Winnie on a 2000 Chevy 3500 chassis:
Chevy 3500 Chassis
VIN: 1GBJG31J1Y1176395
Model: WF324V
Displacement: 7.4L / 454 cu in

On a trip to Texas they got the service engine light.

When checking the ODB info I got these four errors:

P0174 System too lean - Bank 2
P0171 System too lean - Bank 1
P0131 O2 sensor circuit low voltage (Bank 1 Sensor 1)
P0134 O2 sensor circuit no activity detected (Bank 1 Sensor 1)

I'm thinking that a failed sensor (the bottom two error codes) could actually cause at least Bank 1 system too lean error code. But I'm not sure that it'd affect the bank 2 code.

I'm not an auto mechanic (I was a mechanic on a nuclear power plant) but I can replace the oxygen sensor and am hoping that'll fix all these errors.

Any input would be helpful.

Until then, I've cleared the errors and will start driving the Winnie to work to see if they come back.

[Arch Hoagland]

I fought intermittant O2 sensor codes for over a year. Replacing O2 sensor had no effect.

Final fix was cleaning the MAF on my 8.1 engine.

The MAF determines the air to fuel mixture and if it's wrong it causes the O2 sensor to do it's job....report a problem.

I don't know if the 7.4 has an MAF but I'd check to see what is common to both of the sensors.

Think about it....two O2 sensors going out at the same time? Not likely.

[lynch763]

Originally Posted by Arch Hoagland

Think about it....two O2 sensors going out at the same time? Not likely.

I think only one sensor went bad - based upon the two codes that point to the same sensor.

[Skip426]

The two codes , PO131 & PO134 do point to the same O2 sensor , and an electrical or wiring issue with the sensor , with no O2 input the ECM ( Electronic Control Module would go into a default fuel supply program , and that program could be too lean at certain load situations ; WOT ( Wide Open Throttle ) for example.
I don't believe your 454 used a MAF ( Mass Air Flow ) sensor , like the later 8.1s do . But I'll check .

[Arch Hoagland]

Originally Posted by lynch763

I think only one sensor went bad - based upon the two codes that point to the same sensor.

Good catch, thought it showed two different sensors. My mistake, not my first either...