P0402

DTC P0402

DTC DESCRIPTOR

DTC P0402
Exhaust Gas Recirculation (EGR) Flow Excessive

DIAGNOSTIC FAULT INFORMATION

IMPORTANT: Always perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

If DTC P0403, P0405, P0406, P0698, or P0699 are set diagnose these DTCs.

CIRCUIT/SYSTEM DESCRIPTION
The engine control module (ECM) tests the exhaust gas recirculation (EGR) flow when the EGR is In operation. EGR desired flow is compared to EGR actual flow. If EGR flow deviation is detected, DTC P0401 or P0402 will set.

CONDITIONS FOR RUNNING THE DTC
- DTCs P0101, P0102, P0103, P0403, P0405, P0406 are not set.
- The engine is running.
- The EGR valve is actively being controlled.
- DTC P0401 runs continuously once the above conditions are met.

CONDITIONS FOR SETTING THE DTC
The air flow deviation monitored by the ECM during the EGR operation indicates insufficient EGR flow for 15 seconds.

ACTION TAKEN WHEN THE DTC SETS
- The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
- The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

CONDITIONS FOR CLEARING THE DTC
- The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
- A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
- A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
- Clear the MIL and the DTC with a scan tool.

CIRCUIT/SYSTEM VERIFICATION

IMPORTANT: If you cannot duplicate the condition, operate the vehicle within the conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame /Failure Records.

If DTC P0403, P0405, P0406, P0698, or P0699 are set diagnose these DTCs.

CIRCUIT/SYSTEM TESTING
Inspect the air induction system for air leaks.
- If no problem is found perform the component testing.

COMPONENT TESTING
1. Using the output controls on the scan tool command the EGR position to 30 percent.
- If the actual EGR position does not move replace the EGR valve.
2. Remove the EGR valve.
- If the EGR valve is sticking, has a weak spring, or is damaged and cannot be cleaned replace the EGR valve.


REPAIR INSTRUCTIONS

IMPORTANT: Always perform the Diagnostic Repair Verification after completing the diagnostic procedure.
- Exhaust Gas Recirculation (EGR) System Cleaning
- Exhaust Gas Recirculation (EGR) Valve Replacement