P1406 OBD2 Error Code Explanation and Fix for 1996 GMC 350 4x4 with Auto Transmission
I own a 1996 GMC 350 4x4 with automatic transmission, stock setup. My vehicle is currently displaying a P1406 OBD2 diagnostic error code. I'd like to understand what this code means and how to resolve it. Any insights or troubleshooting steps would be greatly appreciated. Thank you, Chris
P1406 is an Exhaust Gas Recirculation (EGR) Valve Position Sensor - Range Performance code. This means the Powertrain Control Module (PCM) is not detecting proper movement of the EGR valve pintle when commanded. The most common solution is replacing the EGR valve, as cleaning it often fails to resolve the issue. Wiring problems from or to the PCM are possible but less likely. GM introduced a software update that helps prevent carbon buildup on new EGR valves by cycling them with the key and engine off—this keeps the valve clean during cooldown. It may be worth checking for this specific software update, especially if your vehicle was built after the update period. This could significantly improve performance and resolve the P1406 code. I hope this helps! Please keep me updated on your progress. Jeff