low oil pressure warning but also hear engine tapping.
It could be a bad oil pump, plugged or collapsed oil filter, low oil level or worn engine. That tap you hear may be a rod knock, if so your engine will need a re-build.
The tapping confirms the warning is correct
Certainly the oil pump could be bad. If it was not serviced properly I would suspect a plugged oil pick up screen. I sure wouldn't run the engine till the problem is discovered and repaired.
Looking for a Used Sierra 1500 in your area?
CarGurus has 59,014 nationwide Sierra 1500 listings starting at $1,980.
Search GMC Sierra 1500 Questions
GMC Sierra 1500 Experts
Related Models For Sale
Used Cars For Sale