2000 GMC 1-Ton Box Van P1345 Code: Diagnosis and Fuel System Issues
I have a 2000 GMC 1-ton box van with 68,000 miles and a 5.7L Vortec engine with an automatic transmission. The check engine light came on and triggered a P1345 code. After having the code cleared, it returned shortly after. I previously replaced the water pump before this issue appeared. During inspection, I discovered a hole punched through the fuel pump power wire at the computer module located on the left front of the engine compartment—likely caused by an alarm technician using a test light. I repaired the wiring and subsequently encountered another problem with the fuel pump. A bad connection was found in the fuel pump wire harness plug at the transmission. After swapping pins at this connector, the engine starts and idles smoothly. This is a work truck that often sits idle for more than a week. When I start it and let it run for about 10 minutes, it begins to missfire slightly while driving—though the issue resolves on its own after some time. Initially, I thought this might be due to a weak battery causing the engine control module (ECM) to relearn parameters. I’ve pulled up diagnostics using an OBD2 scanner and obtained the following data: P1345 P1345 PD Monitors on 1 INC O2 Heater Does this information provide any insight into the root cause? Any advice or suggestions would be greatly appreciated!
The P1345 code typically indicates a loss of crankshaft or camshaft position signal. This could result in no start, prolonged cranking, or engine misfires. Could this be related to the crankshaft position sensor or distributor assembly? When you replaced the water pump, did you remove the harmonic balancer? Let's keep an eye on updates—good luck!