EGR P0400, P0401- P0409 Diagnosis+Understanding Pt1

Diagnosis and Understanding of EGR (Exhaust Gas Recirculation) systems. Part 1 describes general EGR function and explanation of operation, components, and diagnosis of vacuum-solenoid controlled EGR systems. Part 2 is HERE:    • EGR  P0400, P0401- P0409 Diagnosis+Underst...   Helpful links for more info: MAP Sensor Diagnosis and Understanding::    • MAP Sensor Diagnosis and Understanding Fun...   Vacuum leak diagnosis using fuel trim:    • Secret of Engine Problem Diagnosis- Fuel T...