I'd appreciate some help on this issue before I take it in for a diagnostic. I live in a hot climate and I just got the dreaded check engine light on.
Any suggestions?

 

The only thing I can really suggest is to make sure the gas cap is on all the way.

Stop by your local Auto Zone and have them pull the codes.

 

thanks...
I'll let you know what happens

 

Ok cool.

 

OK
Looks like the Auto-Zone is a good place to get a diagnostic (free is good). Turns out the code was P0172 and I was told that it was due to a faulty fuel/air ratio. So maybe that means too much gas and too little air or any thoughts?

 

Could be a massflow sensor going bad,A coolant temp sensor going bad,or a vaccum leak.

 

Volvo pulled the codes and said that it indicated a misfire, fuel trim level was off, and air flow sensor issue. But when they went to check it out, they found nothing wrong with either. We purchased the car used with 67K and the dealer washed the engine before they put it on the lot, so the mechanic said that this sometimes causes temporary problems. They cleared the CEL and said the car drives fine. Should we pursue this further since its under warranty or take it home and see what happens?
Thanks

 

Drive it and see what happens.

That is true if the engine is washed with water it will cause it to missfire.