my check engine light is on
HAVE IT SCANNED AND GET THE PROBLEM FIXED
If you take it to your local GM dealer they will have the proper scan tools to retrieve the codes that were stored in your computer- this will tell them what needs replacing (some common causes- bad 0xygen sensor, loose gas cap or corroded filler neck, etc.)
Search GMC Sierra 1500 Questions
Are you a UK consumer? CarGurus now has a discussion forum in the UK.
GMC Sierra 1500 Experts