Question: I have an 2006 Pontiac G6 that went for emission testing, it failed due to the fact that they couldn't get a reading from the OBD plug. I have checked all the fuses with no luck. I even hooked up my OBD scanner and it just shows no link. Anyone experience this?
Answer: First be sure to check all the fuses. If they are good, it sounds like your Pontiac G6 either has a wiring problem or a bad computer.
There is one wire that is called the "Communication line" that the connects the OBD connector to the Powertrain control module. If this wire is shorted or broken, the scanner will not be able to read the computer. This will not effect the way the car runs at all because it is just for communication. You will need to get a wiring diagram and do some testing. Check a the large electrical connector behind the panel on the drivers side of the dash. Open the driver side door and pull that side panel off. Disconnect the connector and look for corrosion caused by water intrusion. This would look like crusty green. If it is, clean the terminal and apply some silicone grease.
Checking the PCM operation is a bit harder. First make sure the check engine light is on with the key in the "ON" position. If it is, then more detailed electrical testing would be needed to check that the computer is working properly. If the light does not come on, it may be bad.
Oil Light On
Question: Oil light come on then died didn't wanna crank over then cranked over and started making a knocking noise on a 2009 Pontiac g6
Answer: Either the engine has no or very little oil in it, or there is no oil pressure. Not wanting to crank means the engine is starting to lock up. Knocking means the engine has significant internal damage and needs to be remove, taken apart and repaired or even replaced.