Engine Misfire Due to Worn Valve Seat on GMC 1500 Pickup

The engine may develop a misfire due to worn valve seats. This fault will cause the Check Engine Light to illuminate. Our technicians tell us the misfire may or may not be felt while driving. They further recommend that both cylinder heads be removed and thoroughly inspected and repaired as necessary.

RepairPal Verified
Average mileage: 135,000 (135,000–135,000)
Engine affected: 5.7L V8
4 model years affected: 1996, 1997, 1998, 1999
5 people reported this problem
Get Your Car Fixed at a RepairPal Certified Shop.
We certify shops based on expertise, quality work, and verified customer reviews
Viewing 1 - 1 of 1 problem details
1998 GMC 1500 Pickup - 5.7L V8 135,000 mi,
check engine light won't go out. Po300 and PO306. Engine runs smooth. Did full tune up-cap, rotor, plugs, wires, even replaced 02 sensor and all fuel injectors. Code still on but truck runs fine