P1345 Fault Code in 2000 Chevrolet Blazer 4.3L V6 2WD: How to Diagnose and Fix
I recently purchased a 2000 Chevrolet Blazer with a 4.3L V6 engine, 2WD, automatic transmission. The vehicle came with the service engine light on. After using an OBD2 scanner, only one fault code appears: P1345. The truck runs smoothly without any misfires or stalling—no performance issues at all. I've been told it could be either the crankshaft position sensor (CKP) or camshaft position sensor (CMP), but I'm unsure which to replace first given their relatively high cost. Since both sensors are expensive, I'd like to know what diagnostic steps to take before replacing any part. Can anyone provide guidance on how to identify and resolve this issue? Thanks in advance.
P1345 indicates a correlation issue between the crankshaft position (CKP) and camshaft position (CMP) sensors—meaning they don't agree on top dead center for cylinder #1. This is often caused by improper distributor installation, such as when the distributor was moved during previous repairs or when a new cap/rotor was installed without proper alignment. Even slight excess timing chain slack can trigger this fault. If you have an OBD2 scanner: check sensor correlation (also known as sync and cam retard) to confirm misalignment. Then, carefully adjust the distributor back to 0° ± 2° for optimal timing. Without a scanner: search YouTube for DIY tutorials on fixing P134 or P1345 in 4.3L Blazer models—note that the 4.3L and 5.7L engines share similar issues due to different distributor markings. Always ensure the distributor is correctly aligned with the timing marks. Remember: turning the distributor does not adjust ignition timing—it only affects sensor alignment.