I'm encountering trouble code P1345 on my 1999 GMC Suburban. I understand this relates to the engine timing, but I'd like to know exactly what steps I should take to diagnose and fix it. Can someone provide clear guidance on how to address this issue?
Thank you for the response—the issue was resolved. However, I now have a new code: P1404 (EGR pintle valve stuck). I replaced the EGR valve, but after 20 miles, the same P1404 code returned. Any ideas? During my smog test, the engine would drop idle by about 200 RPM on its own and then recover—this behavior seems suspicious. Could a faulty EGR valve be causing this, or is there another underlying issue I should investigate?
There are two common causes of P134-45 in a 1999 GMC Suburban: first, the distributor was removed and reinstalled incorrectly; second, the distributor is worn out. To confirm, you should use an OBD2 scan tool to check the camshaft position sensor data—specifically the crankshaft position angle—and verify it falls within the specified range of 0° ± 2°.