Hi, I’m getting my ‘03 back on the road after some time in the garage and I was getting a P0130 O2 sensor fault. I replaced all four sensors with Bosch and now I am getting a P0135 and P0155 pending code. I know these are both Heated O2 sensor faults. I cleaned both plugs with contact cleaner when changed and a dab of dielectric grease. I am seeing voltage being sent to the sensor, and resistance through the sensor. Everything seems to be connected properly. What else can cause the heated O2 sensors circuit fault? The engine seems to be running fine. Smooth idle etc. Any thought would be appreciated, got to get this thing to pass emissions. Thanks!

 

How do you know the old sensor were bad? Very rare for DS sensors to be bad.

 

I had P0130 code with the SES light on. Easier to change them out and see if code goes away. I’ve had several through the years with this truck that have given the P0130 fault. Changed the sensor and went away. Owned it since 07. Never had it change to a 135 and 155 code.

 

Because of the DOA issues I always try to chart the outputs first, then start swapping left/right to isolate it really is a bad sensor before I change everything. $5 for an elm327 and $10 for a cheap android phone and you can see everything with the torque app.

 

Thanks for that tip! I don't have an ELM327, but I'm going to get one. Didn't know there was a app that displayed real time data.

 

Finally got around to messing with the disco again. So I got an elm327 to read real time data. On the drivers side bank I'll see fluctuations in readings, and at some point it will drop to 0. Then a P0130 fault will pop up. I've cleaned the connection and used Dielectric grease. I am thinking that I have a broken wire somewhere in the harness causing a poor connection. Any thoughts?

 

Post screenshots of the graphs. Does it start fluctuating cold and then go to zero? One side only? If one side only swap left and right see and it moves.

 

I think your problem is 2 new bad Bosch O2 sensors. Bosch O2 sensors are iffy on being good right out the box.

 

If you're certain that the connections are good then I'm with Juke, bad heater circuits means bad sensors. I got 0135 and 0155 when I reinstalled my Y pipe, there were no codes previously. I pulled it back down and noticed that one of the white wires had broken off the pin on Bank 1 Sensor 1. I took the connector apart and repaired the connection, reinstalled the pipe and the code disappeared.

 

Here are the graphs of the drive yesterday. Note the voltage on Bank 1 is MUCH lower than Bank 2. Right now I am just getting the P0130 code.