The codes are telling me that all my O2 sensors are bad! About 1yr ago, I got an error code for one of my pre-cat O2 sensors (Not sure which one, will need to search the archive) and I replaced it with a Bosch sensor.

Now, about 1yr later, I get all these codes... <img src="/forums/images/graemlins/zombie.gif" alt="" /> Are all of my sensors now bad or could it be some weird electrical problem???


P0134 - 02 Sensor Circuit No Activity Detected (Bank I Sensor 1)
P0135 - 02 Sensor Heater Circuit Malfunction (Bank 1 Sensor 1)

P0141 - 02 Sensor Heater Circuit Malfunction (Bank 1 Sensor 2)

P0154 - 02 Sensor Circuit No Activity Detected (Bank 2 Sensor 1)
P0155 - 02 Sensor Heater Circuit Malfunction (Bank 2 Sensor 1)

P0161 - 02 Sensor Heater Circuit Malfunction (Bank 2 Sensor 2)


P1870 - Transmission Component Slipping

To me, I'd start checking the wiring harness and make sure it hasn't gotten melted/cut/etc. If that all checks out, then I'd start checking the components themselves.

Richard <img src="/forums/images/graemlins/patriot.gif" alt="" />

Good advice. My front left (driver side) O2 harness is kinda melted.

Why did Isuzu design it like this?? O well...

Would this one melted harness effect all of the other sensors and throw the errors as previously listed?

Thanks again!

I agree that these o2 sensors locations are not ideal. What were they thinking? If you were fouling up your o2s after just one year I think you'd notice the truck running really rough. You can test the o2s on a bench if you have a propane torch and a multimeter. Here's a link that shows how

How can I fix the engine side harness??? On the O2 side, I can just get a new sensor, but what can I do about the other side?
Thanks