LS6 P0133 and P0153

[pormgb]

My LS6 swapped 944 is getting P0133 and P0153, the car has run fine for quite a while with only P0300 bothering me, I have already swapped the front O2s but the codes are still coming. The O2s are in the headers about 2" behind the 3 bolt flange, I thought the codes could be caused by exhaust leaks.

I done some logging with a Calc Vet pid selection, this has me stumped, has anyone had this issue and found an electrical or tune issue?

I have attached my tune and a log taken, I drove the car for around 10 minutes then the my CEL lit up, the CEL lit up while capturing the attached log.



2182421825 today

[statesman]

Both your O2 sensors are constantly hanging around 450mv.... which means that they ain't working. If you've already replaced the O2 sensors, then check your wiring and also check the fuse for the O2 sensor heater circuit.

[pormgb]

Both your O2 sensors are constantly hanging around 450mv.... which means that they ain't working. If you've already replaced the O2 sensors, then check your wiring and also check the fuse for the O2 sensor heater circuit.

Checked heater voltages, they show up around 11.71v at the plug, grounds are good. I will trace and check the signal wires to the PCM, I also have a spare PCM that I can switch in.

Thanks!!

[pormgb]

Switched the PCM and checked all wiring, same issue. I done some additional troubleshooting, and here is what I found.

Tested heater voltage with car running, got 13.2v.

Disconnected the RH O2 sensor and read the voltage, went up to 712mv as the O2 warmed up. My car initial start up is always lean, between 15 and 17 AFR, 712mv seem about right for initial start up.

Could my O2s be OK but the motor is not going into closed loop?

[joecar]

The PCM biases the NBO2 signal voltage to 450 mV, the NBO2 adds it's own signal voltage on top of this (i.e. very similar to AC on DC).


Your front NBO2 voltages (pids GM.HO2S11/21) are hovering at 450 mV as statesman said above... this means there is an open between each NBO2 and the PCM.

[pormgb]

The PCM biases the NBO2 signal voltage to 450 mV, the NBO2 adds it's own signal voltage on top of this (i.e. very similar to AC on DC).


Your front NBO2 voltages (pids GM.HO2S11/21) are hovering at 450 mV as statesman said above... this means there is an open between each NBO2 and the PCM.

I think, I may have found the problem.

When I first got the codes, I immediacy bought two new O2s, I picked some cheap ones on Ebay. I then discovered that I had a bad ground on the heater circuit that I fixed but kept on getting codes.

Yesterday, I done some logging (motor not running) with the new O2s and noticed that they were stuck between 435mv and 450mv, I then switched back to the old O2s (NTK) and I got about 135mv when warmed up (motor not running).

I think my original problem was a bad ground reducing the heater voltage, for some reason the new O2s don't work on my motor. The new O2s are for a LS1+LS6, I tested them with propane torch and I did see them swing from 100m to 900mv but they do not switch connected to the PCM.

[pormgb]

Ran the car today, no CEL and O2s are switching.

[statesman]

Glad to hear you got it fixed. :cheers:

[joecar]

Good job :cheers: what did you find to be the cause...?

[pormgb]

Good job :cheers: what did you find to be the cause...?

After reinstalling the original O2s, they started to switch as expected. The original problem was caused by a bad heater ground, I then added to the problem by installing new O2s that for some reason won

[pormgb]

Well, after three weeks, I now get P1153 and P1133. It started with 1133 that popped up yesterday, I cleared the codes and got both 1133 and 1153 today.

I am going to try a set of BOSCH 13111 based on some other threads I have read on the forum, any other ideas why I would be getting these codes.

I have attached a log taken yesterday after P1153 appeared and it was cleared, the O2s are switching.


2198221982