I recently bought a 2001 Dodge Ram 1500, 5.2L, reg cab, 2WD, auto, single exhaust. CEL was lit when I bought it. The error codes are P0031 and P0037, which have to do with the heater circuit for the O2 sensor. I changed the pre cat sensor, reset the computer, codes came back.

Had a mechanic friend look over the wiring and said he found a frayed wire going to an O2 sensor. He fixed it, cleared the codes but they came back.

I've checked the fuse several times for that circuit and it's fine. Double and triple checked all connections, I even swapped out the PCM and the codes popped immediately.

Could the cat be the issue? Should I go ahead and replace the post cat O2 sensor as well? As it stands, it won't pass emissions here in Texas so I can't get it inspected or registered.

Any suggestions? I appreciate all the help I can get with this one.

 

Cat has nothing to do with it.

There is a heater circuit in your sensors, so they "get ready" faster. Grab the 01 service manual from this thread, take a look at the wiring diagrams, and do a bit of troubleshooting. Make sure you have power where it needs to be. If not, find out why.

 

That's NON-California emissions. Just 2 O2 sensors.

 

That's NON-California emissions. Just 2 O2 sensors.

Here's the odd thing about that. When I went to replace the sensor, the first one they gave me had a different connector than what I took off. When I went back and they tried to match up the sensor I had removed, they said I needed the California emissions sensor. That was the only one that had the connector that would work. But you are correct, it only has the two sensors. Also, the title shows this truck was originally titled from a dealer in Texas.

I know my way around an engine compartment pretty well, but following testing all the wiring for voltage, resistance, etc is a little intimidating. Thanks for the diagram.

 

It makes things much easier when you can actuate the heaters with a scan tool for sure.

 

Is there a bias voltage on the oxygen sensors?

 

They are heated O2 sensors. Four wires, 12 volt feed, 5 volt feed, signal return the to pcm, and a ground. (for the heater circuit) Voltage on the signal return should bounce between 0 and 1 volt. (engine running.)

 

Hi, thanks for responding, I have a 2001 dodge ram 1500 5.9 that is throwing code p0037 for bank 1 sensor 2 the computer was replaced a couple weeks ago for a idle air code but that code is gone. How should I go about testing for this code? Thanks.

 

If you are only getting the code on one sensor, replace the sensor. If you are getting it on more than one, that's likely a wiring issue.

 

hi, both sensor's are new Bosch ones, and the catalytic converter is new OEM from napa. I got 12 volt for a second on the wire that goes to the auto shut down relay for the heater should it be on longer?