How to Fix P1345 Code on 2001 GMC Sonoma 4.3L with Cam Offset Issues

P1345 typically indicates a camshaft position sensor (CMP) or crankshaft position sensor (CKP) correlation issue—specifically, a misalignment in TDC reference points. Check if your OBDLink MX scanner displays 'cam offset' or 'cam sync'. The ideal value should be within ±2 degrees at 1000 RPM. If the scanner doesn't show this data directly, there are known workarounds to retrieve it manually through PID entry.

After manually entering the cam offset PID on my OBDLink MX scanner, I discovered that the distributor on the 2001 GMC Sonoma 4.3L is not factory-adjustable—its hold-down bracket fits into a fixed square slot with no slotted hole for fine-tuning. While slight wiggling before tightening may allow minor adjustments (a few degrees), it's limited. My readings show a cam offset of -26°. After removing the distributor and rotating it one gear, I reinstalled it and observed +27°. When I then rotated it just one tooth backward (instead of a full gear), the reading returned to -26°. This suggests that each tooth movement results in a significant shift: -26° for one direction, +27° for the opposite. This indicates that the distributor cannot be adjusted to reach 0° cam offset. Given this, I suspect the timing chain may have skipped a tooth—this would explain why the cam offset readings are so far off and could directly cause P1345. A missed tooth in the timing chain can misalign the camshaft relative to the crankshaft, triggering the fault code.

I always start with simple, low-cost solutions first—like checking basic components before assuming mechanical failure. Before investigating camshaft timing issues, I recommend watching a DIY video on how to diagnose and adjust cam offset in this model. Here's a helpful guide: https://www.youtube.com/watch?v=4G9_aCu2Bgw