Need some 02 sensor help -

[str33tz]

Just purchased a 08 Tahoe 4.8.
Runs and drives good until it throws a check engine light for o2 sensor codes for all 4 sensors and pops both fuses for sensors. After fuses blow Truck will slowly start idling rougher, and then after a few starts barely wants to stay running. Will drive ok for a bit while on the gas, then really starts running rough. Replace o2 sensor fuses and it’s good for a while.

I’ve checked all wiring and as far as I can tell it all appears to be good. I’m getting power (with a good fuse) and ground on corresponding wires on the truck side of the o2 plugs.
O2 sensors appear to have been recently replaced.

I’m having a tough time finding “aftermarket” pin outs for the sensor side. I’m wondering if the sensors are not pinned correctly for the truck side.

Here’s what I have for pin outs from truck to o2.

bank 1 sensor 1 - (drivers side pre cat)
Purple/white to blue
Tan to white
Brown(tan maybe?) to black
Pink to black

bAnk 1 sensor 2 drivers post cat
Pink to purple
Black to white
Purple to black
Tan to grey


Bank 2 sensor 1 pass pre cat
Tan to white
Purple to blue
Green to black
Pink to black

bank 2 sensor 2 pass post cat
Tan to grey
Purple to black
Pink to purple
Orange to white

I feel like these either are the wrong sensors and are pinned incorrectly. Got power and ground at plugs on factory side until fuse pops which leads me to believe the pins on sensor side are incorrect and the power is shorting to ground.

possible front/rears are mixed up? Since sensors appear new, I’d like to try swapping some wires if something doesn’t match up before I throw a few hundred bucks at new sensors.


Any advice, help us greatly appreciated. Thanks in advance!

 

[wjburken]

Just purchased a 08 Tahoe 4.8.
Runs and drives good until it throws a check engine light for o2 sensor codes for all 4 sensors and pops both fuses for sensors. After fuses blow Truck will slowly start idling rougher, and then after a few starts barely wants to stay running. Will drive ok for a bit while on the gas, then really starts running rough. Replace o2 sensor fuses and it’s good for a while.

I’ve checked all wiring and as far as I can tell it all appears to be good. I’m getting power (with a good fuse) and ground on corresponding wires on the truck side of the o2 plugs.
O2 sensors appear to have been recently replaced.

I’m having a tough time finding “aftermarket” pin outs for the sensor side. I’m wondering if the sensors are not pinned correctly for the truck side.

Here’s what I have for pin outs from truck to o2.

bank 1 sensor 1 - (drivers side pre cat)
Purple/white to blue
Tan to white
Brown(tan maybe?) to black
Pink to black

bAnk 1 sensor 2 drivers post cat
Pink to purple
Black to white
Purple to black
Tan to grey


Bank 2 sensor 1 pass pre cat
Tan to white
Purple to blue
Green to black
Pink to black

bank 2 sensor 2 pass post cat
Tan to grey
Purple to black
Pink to purple
Orange to white

I feel like these either are the wrong sensors and are pinned incorrectly. Got power and ground at plugs on factory side until fuse pops which leads me to believe the pins on sensor side are incorrect and the power is shorting to ground.

possible front/rears are mixed up? Since sensors appear new, I’d like to try swapping some wires if something doesn’t match up before I throw a few hundred bucks at new sensors.


Any advice, help us greatly appreciated. Thanks in advance!

Might be more likely to get some assistance if you posted this in the 2007-2014 section of the forum.

Maybe an admin can move it for you.

@yates ™ , @07Burb ?

 

[915_Tahoe]

GM#12583804 x2 $88.90 Ech. Left Front/Right Front

GM#12609457 x2 $92.98 Ech. Left Rear/Right Rear

 

[Fless]

Eric O shows some testing of an o2 heater, and I would expect the '08 sensors to be similar. Early on there's some good info about colors on the truck side, at around 9:45 he ohms out the o2 heater.

 

[07Burb]

Might be more likely to get some assistance if you posted this in the 2007-2014 section of the forum.

Maybe an admin can move it for you.

@yates ™ , @07Burb ?

Done. Thanks for the heads up

 

[OR VietVet]

If the sensors look relatively new, you can remove and swap the fronts with the backs and see if that fixes plus you can check part numbers and compare to what part #'s Rene gave you. You may also have bad cats but I would not see where that would blow fuses. I would love that info if in fact the bad cats could do that.

 

[str33tz]

Sensors appear to be pinned correct. Getting heater circuit readings of 5.7 ohm and 6ohms which is what the codes started popping up as.

Have not checked resistance warm yet on other two wires. Currently chasing grounds around.

anybody know what this plug could be for? Light green and dark green. Pass side of core support. Thought it’d be ambient air temp sensor but that appears to be on the drivers side and plugged in. Maybe if I had option for parking sensors? Or supposed to be an airbag impact sensor plugged in? I don’t have any airbag lights or warnings on.


The chase continues.

 

[str33tz]

Quick update - bought replacement oxygen sensor for bank 2 sensor 1. Was and still Getting p0050 as soon as truck fires up, immediately pops up after clearing DTCs. New sensor came with female plug, however truck side for pre cat 02 has a female plug. Cut and swapped on the old connector being sure pins a b c d all correlate correctly and still getting p0500 as soon as soon as I clear the code.
I’m also getting u0109 -lost communication to fpcm, as well as a code for steering angle sensor which trips stabilitrak light.

I’m having trouble finding a fpcm “box” as shown in many other videos/threads - mounted to crossmember in front of fuel tank, or above spare. I’m also noticing the fuel pump doesn’t audibly prime before firing up the truck, not sure if it’s supposed to or not. Possible my truck doesn’t have a fpcm “box” and it’s contained in fuel pump itself?

possible all these could be related?

Boy do I love chasing electrical gremlins. thanks in advance!

 

[swathdiver]

Quick update - bought replacement oxygen sensor for bank 2 sensor 1. Was and still Getting p0050 as soon as truck fires up, immediately pops up after clearing DTCs. New sensor came with female plug, however truck side for pre cat 02 has a female plug. Cut and swapped on the old connector being sure pins a b c d all correlate correctly and still getting p0500 as soon as soon as I clear the code.
I’m also getting u0109 -lost communication to fpcm, as well as a code for steering angle sensor which trips stabilitrak light.

I’m having trouble finding a fpcm “box” as shown in many other videos/threads - mounted to crossmember in front of fuel tank, or above spare. I’m also noticing the fuel pump doesn’t audibly prime before firing up the truck, not sure if it’s supposed to or not. Possible my truck doesn’t have a fpcm “box” and it’s contained in fuel pump itself?

possible all these could be related?

Boy do I love chasing electrical gremlins. thanks in advance!

Start with the battery. It might be strong enough to start the motor but has internal shorts or is not providing enough electricity to some modules. Some run fine on 5 volts, other shut down at 9, others at 11, etc.

O2 sensors ought to be GM OE or ACDelco Professional. The rest are well known to cause issues. Check your grounds and battery cables for corrosion. I suspect you have a failing ECM but let's rule out the cheap and easy stuff first!