I just did a DTC check due to the check engine/ emissions light, and got DTC SET's for the ECM and CEM. Any idea to what it can be? as I hate bringing it to Volvo where they often just bs around and leave me with an insane bill. The car has been acting strange lately; such as irregular shifting (missing 3rd gear in many occassions where it revs up and seems to just drop) and a sort of "puttering" feeling when the car is stopped at a light. Any help is GREATLY APRECIATED!!!

 

also for the hell of it i tried getting the check engine light to go away by holding the odometer button and all i got were the numbers "42" and "58" and the light was still on. Anyone know what these numbers mean? Im only used to fixing mustangs, corvettes, and camaros so these volvo engines are a little bit different.

 

You will need to use an OBDII scanner to pull and clear codes. But it will only work on the ECM.
You will need a Big setup to read codes from the CEM.

Those are error messages for trying to clear the SERVICE LIGHT.

Those codes mean nothing.