EGR Fault Codes Explained: P0401, P0402, P0403 and P0404 on Modern Diesels
EGR Fault Codes Explained: P0401, P0402, P0403 and P0404 on Modern Diesels Four codes, two completely different problems. P0401 and P0402 are about how much exhaust gas is actually moving. P0403 and P0404 are about wiring and position feedback. Read them in the wrong order and you end up buying a valve you never needed. […]