2004 Ford F350 6.0L Diesel P0404 and P0405 EGR Fault - After Rebuilding Engine

Model: F350 Fault Code: P0404 Posted: 2022-09-03 17:05

Hello, I recently rebuilt the 6.0L diesel engine in my 2004 Ford F350. The fault codes P0404 and P0405 are related to the Exhaust Gas Recirculation (EGR) system. One component I did not replace during the rebuild was the EGR valve itself. All engine wiring harnesses were replaced with original Motorcraft stock harnesses, and all other valves and sensors have been fully replaced. The EGR valve appeared to be in good condition, which is why it was retained rather than replaced. Before returning the vehicle for a full diagnostic check, I'd like to know if there are any common issues or troubleshooting steps associated with P0404 and P0405 codes when using an older EGR valve in a rebuilt 6.0L diesel engine. Any insights or recommendations would be greatly appreciated. Best regards, Manic Mike