P0102 Diagnostic and Fix for 1998 Chevrolet K1500 350 Engine

Ensure all air ducts are properly connected and that the mass airflow (MAF) sensor is installed in the correct orientation. Verify that all ground connections, especially those attached to the thermostat housing stud, have been securely reconnected.

All components are correctly installed. The air ducts are fully connected and sealed. No aftermarket modifications have been made—this is a stock vehicle setup.

Check the wiring on the MAF sensor: the pink wire should show battery voltage with the key ON, the black wire should be grounded, and the yellow wire serves as the return to the ECM. Confirm power is present on the pink wire first. If no voltage is detected, inspect the fuses in the underhood fuse box for any blown fuses. If all electrical checks pass, consider that the intake manifold reassembly may not have been completed properly—there could be a vacuum leak or an intake gasket leak allowing unmetered air into the system.

I identified the issue: there is an O-ring located around the fuel meter body, positioned just inside the upper intake manifold. I had been working only on the lower intake when removing the upper intake, so this O-ring was overlooked. After installing a new O-ring, the P0102 code cleared and the problem is resolved. Thank you for the helpful suggestions.

I now have a P1345 code. I've adjusted the distributor one tooth counterclockwise, and while the engine runs fine, the check engine light remains on. Should I move it two teeth clockwise or should I replace the crankshaft position sensor instead?

The only reliable way to diagnose this is using a scan tool to monitor the cam shaft position (CAM R**ARD) PID, which should read close to 0 degrees. Make sure the distributor isn't rotated too far—ensure that the cap's plug towers are aligned parallel with the firewall. If significant rotation is required to achieve proper alignment, it may be necessary to remove and reposition the distributor.