2004 Ram QC 4x4 Hemi SLT 115k miles

Getting a P0058, 2 errors thrown before start. Just turning the ignition on causes it to throw codes. That is bank 2, sensor 2, hi heater circuit.

I replaced the original passenger side rear sensor in December with a Bosch. It was throwing a different code then (P0157), but same bank 2/sensor 2 unit. Was good for a while, but it did throw this P0058 code in January. I cleared it and it didn't come back.

Then I had an EGR valve failure, so it had the light on all week. Replaced the EGR valve Sunday morning, and noticed that P0058 was back.

I just popped a new NTK 02 in there this morning, and then cleared the codes. Soon as ignition goes on, codes come back! I cleared again, started it... cleared again.. still coming up with two of these P0058 codes

It is unlikely that I have 2 new dead O2 sensors. What else should I look at? Wiring looks fine underneath the truck.

I'm assuming bank 2 is passenger side. I haven't touched any of the other sensors.

 

That code almost always indicates that there is a short in the wiring somewhere...

Most common areas to check are harnesses and connectors (sometimes they melt), then look at any place the wire bends or makes a turn.

Other things can cause this code too:

PCM needs Reflashed (not common but possible)
O2 Sensor (you tried it)
Heater Ground Circuit is Open (most likely)
Heater Control Circuit is open (most likely)
Control Circuit Shorted to Battery Voltage. (most likely)

Get a multimeter on the wires on the truck side of the harness for that sensor and let us know what you see.

 

Thanks, I'll see if I can get to that tonight.

Yesterday morning I checked the 2.5 month old Bosch. I assumed that the two white wires would be the heater circuit. My fluke meter reported 3.2 ohms.

I was thinking of pulling the original left 02 sensor off and plugging it into the right harness, see what happens. I could also pop the new one into the left socket and see if it tosses codes on the left side.

I'll check the right side connector with the DMM as you suggested. I looked at the manual (8W-30-18.pdf). Diagram indicates BR/GY and BK are the control circuit, should I see 12v across those pins? Also assuming the color codes mean brown with grey stripe and black wire pin outs?

One thing that tripped me up in the past, the DMMs don't draw much current - and can fool you into thinking the circuit is ok when in reality it can't push enough current to be viable. Should I toss a resistor across the circuit and measure that voltage? If so, what resistance/watt?

Thanks,
Paul

 

You need to check for a short to ground on the O2 sensor circuits on the truck side...

So basically measure the current to ground, if you are getting an Overload then you know the wiring insulation has likely worn away and is grounding to the chassis.

That is the most common issue.

As for testing the O2 Sensor on the opposite bank that is perfectly fine to do, just make sure you clear the codes each time so you can identify the problem.

Also try not to run with them swapped if the problem does not carry over to the opposite bank as you will quickly ruin the good sensor that you swapped.

As for the lack of draw on the circuit... you should be checking it to ground while the truck is running to simulate the DC current short (if there is one), just be careful while doing that... I assume no liability if you get hurt, so do at your own risk.

There are a million ways to check the circuit, but you are simply looking for a short to ground.

 

I found a better manual reference. Its page 8W - 80 - 81

Here is the diagram: