I recently just purchased a 09 Cobalt SS 2.0 LNF. When I first drove it I noticed that it did not have the "power" that it was supposed to but I planned on eventually fixing it up anyways. When I got home I started looking under the hood to see where I should start and found the notorious air tube that breaks on everyone. I bought the ZZP intake tube to fix the problem and immediately after installation the check engine light came on throwing a P0100. I cleaned the MAF first, erased the code but it came back. I then bought one from a local auto parts store and it did the same thing. I then checked the connector for the maf and all connections. I did notice on the pids on my scanner that the maf g/s reading is set at 655.35 at all times and never changes. What could be the problem? To add to this I cannot seem to find any wiring diagrams to help search further into the wiring diagram for a problem somewhere else so if anyone has access to one it would be helpful..

 

It sounds like you might have an open circuit. I don't remember what the exact value is, but it's something higher that you would see normally. You should be able to confirm by watching the scanner and unplugging the MAF. If there is no change, then that is likely the issue. IAT is a separate signal, so that should change when you unplug it.

 

Thank you for the diagram. I was sure that it was an electrical problem but did not know where to start. I honestly still don't understand how it would show immediately after i changed the intake tube. Do you have any tips on how to diagnose the wiring problem? Or a diagram of the ecm plug to show the pin numbers?

 

I know i am going to sound dumb but the iat and maf are the same sensor with different signals?

 

Yes they are tmap sensors

 

It could have been intermittent before and not necessarily had a DTC. You could try what I suggested in my last post. It should help confirm if it is a wiring issue. You would need a meter to do any further troubleshooting. The diagram I posted does show the ECM pins.


TMAP is temperature and manifold absolute pressure, that is a separate sensor.

But yeah, MAF is temperature and air flow.

 

yes you are correct, i completely read that wrong

 

Hey guys, i found the problem yesterday and it is now fixed. I learned that if the maf is bad the iat would still be correct on the scanner and mine was showing 127*. The yellow wire somehow was broken inside the connector. I soldered a new connector on and it is now fixed. Thanks again for the diagrams