Code 63, 64 Or 65, EGR Flow Check Error Using Tech 1

On a closed throttle coastdown, ECM energizes solenoids inside of EGR valve and monitor changes in RPM and O2 sensor activity. If expected changes do not occur, appropriate code will be set. Code 26 in conjunction with Code 63, 64 or 65 indicates a possible quad-driver problem. Before using this chart, use Code 26 chart, clear codes and test drive to see if EGR codes reset.

NOTE: Test numbers refer to test numbers on diagnostic chart.

A noticeable change in RPM should occur as each solenoid is cycled on. Solenoid No. 1 should cause the smallest change in RPM and solenoid No. 3 should cause the largest change and may even stall the engine.
Checks for an open circuit in harness between EGR valve and ECM, faulty ECM connection or faulty ECM.

NOTE: If digital EGR valve shows signs of excessive heat (i.e. a melted condition), check exhaust system for blockage (possible plugged converter).

Fig 1: Code 63, 64 or 65, Schematic, EGR Flow Check Error Using Tech 1

NOTE: Use schematic to identify terminal referenced in this flow chart.

Fig 2: Code 63, 64 Or 65, EGR Flow Check Error Flow Chart (With Tech 1)