HE20 - DTC 0402: Check For EGR Flow at Idle

Diagnostic Trouble Code (DTC) 0402 indicates that self-test has detected EGR flow at idle.

NOTE: If DTC 1405 is in Continuous Memory, diagnose that first starting with HE50. HE50 - DTC 1405: Inspect Upstream Pressure Hose Connections

Possible Causes:
- EGR valve stuck open.
- EVR solenoid vent plugged or iced.
- EVR circuit shorted to GND.
- Improper vacuum hose connection.
- Plugged/pinched EGR vacuum hose.
- Damaged EVR solenoid.
- Damaged PCM.

- Key Off.

- Disconnect vacuum hose at EGR valve and plug hose.

- Run Key On Engine Running (KOER) Self-Test. Diagnostic Subroutines (DSR) - Extracting Codes

- Is KOER DTC 0402 output?

YES -- The KOER Self-Test has detected EGR flow at idle. REMOVE and INSPECT the EGR valve for signs of contamination, unusual wear, carbon deposits, binding and other damage. SERVICE as necessary (use Rotunda EGR Valve Cleaner 021-00056, if needed). RECONNECT all components. Complete PCM reset to clear DTCs. Clearing Diagnostic Trouble Codes

Rerun quick test. Diagnostic Subroutines (DSR) - Extracting Codes

NO -- RECONNECT vacuum hose to EGR valve. GO to HE21. HE21 - Check For EGR Flow at Idle With EGR Vacuum Connected