Multiple codes from scanner 02 Sierra 2500

Richard Carrino · December 31, 2020

pulled these codes today. Can anyone help me get started on diagnosing/fixing these issues. I picked up a knock sensor, knock sensor wiring harness, and new intake manifold gaskets which I plan to replace tomorrow.

CamGTP · December 31, 2020

You have two circuit codes for the MAF sensor. Inspect the harness and test the wiring.

Possible there is an issue with the harness/connector and or the sensor itself has failed internally and giving off both those codes.

Plausible that the MAF sensor issue is a cause for the P0300 misfire code but I would want to see the live data of the scan tool on each cylinder to see what cylinders are misfiring. Then I would tackle that part. Could need plugs and wires.

Richard Carrino · January 1, 2021

This truck has had an intermittent misfire since I bought it a little over a year ago. I’ve never been able to solve the issue. Plugs and wires were replaced this year. Scanner was used at a local shop, I don’t personally own it.
I’ll inspect the MAF tomorrow and check the wiring. Electric isn’t my strong suit. Any advice on how to properly diagnose? Air filter is worth replacing as well, something I havn’t done since purchasing.

Richard Carrino · January 2, 2021

I learned the hard way yesterday that the knock sensors on the 8.1 are not under the manifold but on the left and right side of the engine.

The intake manifold gasket was shot though, so it was worth replacing, along with the throttle body and MAP gaskets. The engine was clean but the intake manifold had a lot of carbon build up.
Took some MAF cleaner to the screen and sensor and replaced the air filter which wasn’t too dirty. Upon inspecting the fuse box I found the ENG-1 fuse blown which the MAF is on that circuit. I replaced the fuse and it did not blow so I’m not sure what that was about, I’ll have to watch to see if it blows again.
I tested the wire at the MAF sensor connector. The power reads 12v, resistance was good, and the yellow wire read 5.1 v which I read it should be in the range of 4.8-5.2.
Looking to tackle the bank two knock sensor today.
Anyone else that can shed some light on the issue I’m having or some experience