P0402

P0402-EGR FLOW EXCESSIVE DETECTED

For complete wiring diagrams refer to Diagrams/Electrical.


Theory of Operation

The purpose of this diagnostic is to check for a condition where EGR flow is higher than commanded. This algorithm runs at idle. The diagnostic closes the EGR valve, and limits the intake air throttle valve. It then looks at fresh air flow fraction and the difference in pressure between the exhaust manifold pressure sensor and boost pressure sensor to determine if the EGR valve is leaking. The ECM will illuminate the MIL lamp after the diagnostic runs and fails in two consecutive drive cycles. The ECM will also illuminate the ETC lamp. The MIL lamp will turn off once the diagnostic runs and passes in 4 consecutive drive cycles.

- When Monitored:

Engine running, Coolant temperature above a calibrated threshold, Intake Manifold temperature above a calibrated threshold, EGR valve is closed.

- Set Condition:

When intake throttle is closed, EGR fraction increases more than a calibrated threshold.







Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.

Diagnostic Test


1. OTHER DTCS

Ignition on, engine not running.

With the scan tool, read DTCs.

Are there any other DTCs present?

Yes

- Repair all other DTCs first.

No

- Replace the EGR valve.
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test