Looking at tackling this problem since its supposed to be warm today and tomorrow. I have a p0030 code which the bank 1 sensor 1 heater open circuit. The dealer that replaced the tranny broke some wiring and wont fix it. They put 3 sensors in it and refuse to diagnose it any further. They also ran another wire from the o2 sensor ground to the ecu, so that one's likely good and there is no visible damage on the wiring harness.

I bought an extension for the connector on amazon so i don't have to cut into the factory harness. What I want to do is run a wire from the o2 sensor positive to where ever it connects to. Im assuming It has a positive ignition signal that goes through the fuse box like the climate control. I think I'm going to use an add a fuse adapter to test it temporarily, then try and repin whatever connector is inside the box and run a new wire out the bottom. Is it possible to run a new wire like this? How would I even go about adding a wire to this connector? Id like to get a vague understanding at least before I start.

 

It wont let me edit but I also need the wiring diagram for the sensor plug. Its got what looks like tan, purple with a white line, red, and black with a right line starting at the top left of the connector and working counterclockwise.

 

With key on engine off use a voltmeter to check for 12 volts fused battery feed to the heater element. If there is no voltage present, repair open or short in the B+ feed circuit remembering to replace any fuse blown from the short(Hummer H2 (2008-2010) fuses and relays) If the B+ battery feed is intact, remove the ground (control) circuit from the ECM wiring connector and check for resistance on the circuit. If there is infinite resistance, repair open in the circuit. If the control circuit checks out, suspect a bad O2 sensor.

 

just did that. Found that on the vehicle side pink is switched 12v, and tan is heater ground. Currently there is a good voltage there, but the code usually throws when accelerating hard or hitting a bump. So I’m assuming it’s just barely kind of working. A thinned out wire would cause high resistance and cause the voltage to drop under load and possibly get worse over bumps and such. I’m hoping I can just run the switched 12 volts from a fuse tap and it will work. That would make sense. Once that’s all fixed it’ll be back on to checking out the knock again. Maybe this will fix it.

the 08s run their O2 heaters all the time and regulate them depending on temperature. So the heater is a critical part of the vehicle being able to run correctly even when warm and it could be causing my issue.

 

Is there a wire pinched in the bell housing? If not I would inspect the 02 sensor wires around that area, look for a flattened wire that might have got pinched during the tranny install, they could have pinched it, realized the problem and unbolted the tranny to pull the wire out and leave you with a compromised wire.

 

Shorted B+=blown fuse. Inspect ground.

 

I'll look closer. I haven't seen anything but it's really hard to see up there. I'll look around the bell housing.

 

There's be more to the HO2S sensors than 1st meets the eye, the PCM can detect specific faults on each circuit, in your case the heater ground.

The '04 wiring diagram below shows everything related to the Sensors, apologies for the resolution, but it is readable.

Your colours may differ from the diagram:-
Pin A = Tan = Sensor Low
Pin B = Purple/White = Sensor High
Pin C = Grey/White = Heater Low (shown as B/W) ***
Pin D = Pink = Ignition Voltage




There's also this is a GM diagnostics message for P0030.


Also the attached PDF snippet is taken from the wiring diagram, specifically referencing HO2 sensor repairs.

Better to track down the exact fault and location, e.g. the wiring either side of the sensor connector, or the sensor itself.

GM says P0030 = "The ECM detects that the affected HO2S heater low control circuit is not within a specified range"

This fault refers specifically PCM C2 Pin 72 the Black+White wire (Grey / White)

The Tan wire is "sensor" ground which connects to PCM C1 Pin 29

Pink is the "Hot In Run" O2A Fuse which shares it's 12V with the upstream HO2 sensor on the opposite exhaust (Bank 2)

It does sound like there's a "nick" or break in the B/W or Gray/W wire (or a pinch as @calif phil suggests) giving rise to an intermittent fault caused by movement and/or vibration.

Though it's difficult to access, a very close inspection is called for, rather than over-complicating with additional wiring i.e. the wire the dealer added which doesn't work and is only adding to the possibilities.

 

pdf which didn't attach in previous post.

 

Apologies for the ultra-wide JPG, the resolution got crippled when converted

The attached PDF is better but again only just readable.