GEN 1 P0161 check engine light

[B E N]

Before you dig too far in, make sure you have completed the necessary driving cycles to give the truck a chance to reset the HEGO codes.

This is a 2011 pinout but it should be the same. If I was diagnosing this I think I would pop the connector off and measure resistance in that circuit, if it checks out de-pin the slot at the ECU and measure voltage there. Pin 40, diagram 3 (C1381T).

 

[mike3605]

Just throwing this out there ... if I meter incorrect voltage, can I just splice in from the PCM bank 2 sensor 1 over to the 2nd sensor to "bypass" the PCM (essentially have Bank 2 Sensor 1 power Bank 2 Sensor 2 as well) vs having to chase down either a broken wire, or a bad PCM?

 

[B E N]

Thats a real good question. I have no idea what the draw is or what the PCM can provide. Report back with your findings on the circuit voltage. There are other ways to get regulated 12v if you need it. Also, if it does measure funny check the other bank for comparisons sake. When I was messing around with a coyote control pack I found lots of funny voltages... runs like a scalded rabbit.

I am hoping its a wiring issue, its easy enough to replace a wire or route a spare.

 

[mike3605]

update: I still haven't had time to shoot the wire, however, the check engine light turns off randomly ... then it comes back on after about 15 truck starts. So, it seems to be intermittent?? Very odd, and am hoping it's a wiring/ grounding issue possibly?

 

[raptorbone]

I anticipate, in my case, its a ground wire issue, not power. I measured 10V, so there is power coming from the PCM, but a leak to ground could reduce the measured voltage. The last measurement I need to make is the end-to-end across the ground wire, but I need to sort out the pin at the PCM connector.

 

[B E N]

There is a harness that runs from the middle connector on the pcm, down behind the cylinder head. Check that harness and make sure it hasn't touched the exhaust, or chaffed against the back of the head. It's a fairly common fail point on this gen.