I figured out how to reset the engine system service requiredmessage, but now it will not clear and there are no DTC's. Last week, after reading the thread about timing belts and viewing the pics, I decided to pull the cover and inspect it to find it cracked. hadthe belt, idlers, tentioner and plugs replaced with Volvo parts. After that and replacing the boost sensor the message went away for a day or so but would come and go.Any thoughts would be greatly appreciated.

 

The "Engine system service message" can only be reset by a scanner. Most generic scanners won't read all the codes.

 

Can there be codes present without a check engine light on?

 

Yes there can.
What year is your car?

 

99 t6, but I am woundering if the resivoir boiling issue is the problem.

Thanks,
Bill

 

Possible.