"Service" and "Service Engine Soon" lights are on. No codes (DTC) are coming up. Engine runs great, shifts great, only the tach (will fall to "0" for a second then return to correct RPM) suggests a problem. Two GM dealers took my money and fixed nothing. What's causing the lights to stay on? Thanks
Putnam
Putnam
Nov 11, 2012 at 10:08 PM