LML P0103 (MAF High Frequency)

[snowman22]

Never had this come up before and of course it happens 3 hours from home with the trailer. It sets immediately after start up and also sets again while driving immediately after clearing the code. I cleaned the MAF after limping the truck home and it didn't change a thing. I didn't see any obvious wear on the harness, but I didn't check every inch of it back to the ECM either. Was fine when I parked it last, and showed up as soon as I started to the truck to leave.

Is there a way to check the MAF for continuity/resistance to see if it's in range and the pin out of the harness? I can't seem to find any info on doing that and getting an OEM AC Delco MAF is expensive. No local parts store can even get an OEM one so it's a dealer only thing if they can even get it. I ordered a delphi unit (the only one they could get) but if there is a way to rule out the wiring in the truck or pinpoint the issue with the sensor it would be way better than spending the money throwing parts at it.

 

[Ron Nielson]

1st thing to do is to make sure you have your 5V ref and low ref coming into the sensor. OEM sensors are the best, but others sometimes get the job done too. I take it the P0103 is the only code you have? If so, there are several possibilities for that one. These sheets pertain specifically to my 2008 LMM and you LML may be somewhat different. If you test and find problems based on my info, verify with a known good LML reference.

 

[snowman22]

I’ll check the reference tomorrow, but figured I would have more codes if it was sending a high reference voltage on the reference circuit.

P0103 is the only code I have.


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[Ron Nielson]

If you have access to a scope, you could monitor the input and output of the MAF signal to see when it's happening and see if it is a spike or constant or ??? Backprobe the connector and test under running conditions. P103, at least for my 2008 LMM, says the output is: "The ECM detects that the MAF sensor is greater than 527 g/s for greater than 3 seconds" Since the normal idling MAF output is about 40 g/s, you are wildly out of range. Lots of testing scripts are shown in the P103 attachment. Could be your ECM that is the problem. But I surely wouldn't condemn that without proof.

 

[snowman22]

5v reference checked out so I put a sensor in it and the problems gone. Hopefully the Delphi one doesn’t screw me later.


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[Ron Nielson]

Good news!