CEL for minor errors on IID tool?

[equalizer]

I have a check engine light on out of the blue.
I have been running with a dead aux battery for a while, but that only cause the yellow no Start-stop indicator to light up.
Using the IID tool I can only pull two codes:
From BCM-Body control module
U0241-00 (2E) Lost communication with the headlamp control module A

From GWM-Gateway module
B13C5-92 (2F) Secondary Battery - Component failure - performance or incorrect operation

The second has always been there, but could the first be the cause of a CEL? I thought that only had to do with engine related issues, or major controllers.

Maybe I am not using the IID tool correctly and missing something major related to the CEL. I did exclude the "Test not completed this cycle", but I don't think that is it, is just a setting for the IID tool to exclude some subsystems that might not exist or so.

thoughts?

 

[scapistron]

I live with the same headlamp code and it doesn't trigger a CEL. I'd double check that the secondary battery code is the same one you had been seeing.

I thought I read that when the secondary battery is just old and tired you get the start stop light. When the secondary battery is dead you can get a CEL.

 

[jlglr4]

Agree that the BCM headlight code is not the cause - I’ve always had that as well. I think it might be from having the headlamp delay option.

I’ve also run the car with a dead flat secondary battery and without the secondary battery installed for long periods - never got a CEL from that either.

 

[equalizer]

The IID tool was misbehaving and did not even pull the codes for PCM Petrol engine! After some fiddling with it, I got it to pull the codes from all onboard computers.
I was able to pull an additional code
U0447-00 (2F) Invalid data received from gateway A

Could this be the reason for the check engine light? Nothing else seem amiss. The rest of things seem to be just "
- Test Not Completed
- Test Not Completed This Monitoring Cycle
"

which I think mean nothing.

 

[jlglr4]

Where do you see those “Test not completed” messages? If that has to do with the EVAP system, it might be the cause of your CEL. The evaporative emissions system runs tests after a “drive cycle” and if it cannot complete those tests after several drive cycles, it might set off the check engine light. I suppose the gateway module problem also could raise the CEL and possibly be related to the test not competed message if it is preventing the sensors from delivering the expected result to the computer.

Is the GAP tool VIN coded to the car you are checking? I think it has limited functionality unless it is assigned to that car, though I’m not entirely sure. I’ve also had GAP tools misbehave and one failed altogether. Sorry can’t be of more help on this.

 

[equalizer]

Circling back on this because I figured out that the IID tool was "hiding" some error codes. Maybe a bug in it?

Basically I setup the fault page enabling all information from the OBD2 port. This includes "Test not completed" and "Test not completed this cycle". These basically mean that the testing would need time, or miles driven to have an outcome recorded.
The weird thing is, if I untick those two options in the Gap tool, and query for the faults, I do get a P error - in my case a P0042 error related to one of the oxygen sensors. This explains why the check engine light was on in the first place.

I still do not understand why the GAP IID tool was "hiding" this error code when I was querying for all possible fault/test outcomes.

Thanks all that contributed!