Diagnostic Instructions
DTC Descriptors
DTC P0400: Exhaust Gas Recirculation (EGR) Flow Incorrect
DTC P0402: Exhaust Gas Recirculation (EGR) Flow Excessive
DTC P1402: Exhaust Gas Recirculation (EGR) Flow Insufficient
Circuit/System Description
The engine control module (ECM) performs a flow test on the exhaust gas recirculation (EGR) system during deceleration. The ECM does this by momentarily commanding the EGR valve to open while monitoring the signal of the manifold absolute pressure (MAP)
sensor and the EGR position sensor. If the MAP signal is incorrect for the EGR pintle position, the ECM records the amount of MAP difference that was detected and adjusts a calibrated fail counter towards a calibrated fail threshold level. The number of EGR
flow tests required to exceed the fail threshold may vary according to the amount of detected EGR flow error.
Normally, the ECM will only allow one EGR flow test during an ignition cycle. To aid in verifying a repair, the ECM will allow multiple EGR flow tests following a code clear event.
Conditions for Running the DTC
| • | DTCs P0404, P0405, P0406, P1403, and P1404 are not set. |
| • | The engine is operating. |
| • | The engine speed is between 2,368-3,200 RPM. |
| • | The calculated air flow is between 49-191 kg/h. |
| • | The engine coolant temperature is greater than 70°C (159°F). |
| • | DTCs P0400, P0402, and P1402 runs once per ignition cycle once the above conditions are met. |
Conditions for Setting the DTC
P0400
The MAP changes monitored by the ECM during the EGR flow tests indicate an incorrect amount of EGR flow.
P0402
The MAP changes monitored by the ECM during the EGR flow tests indicate an excessive amount of EGR flow.
P1402
The MAP changes monitored by the ECM during the EGR flow tests indicate an insufficient amount of EGR flow.
Action Taken When the DTC Sets
DTCs P0400, P0402, and P1402 are type B DTCs.
Conditions for Clearing the MIL/DTC
DTCs P0400, P0402, and P1402 are type B DTCs.
Reference Information
Schematic Reference
Engine Controls Schematics
Connector End View Reference
Description and Operation
Exhaust Gas Recirculation (EGR) System Description
Electrical Information Reference
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Circuit/System Verification
- If DTCs P0107, P0108, P0403, P0404, P0405, or P0406 are also set, refer to
Diagnostic Trouble Code (DTC) List - Vehicle
for further diagnosis.
- Ignition ON, operate the vehicle within the Conditions for Running. DTCs P0400, P0402, or P1402 should not set.
- If the vehicle passes the Circuit/System Verification Test, then operate the vehicle within the conditions for running the DTC. You may also operate the vehicle within the conditions that are captured in the Freeze Frame/Failure Records List.
Circuit/System Testing
- Verify that one of the following conditions is not present:
| • | Incorrect EGR valve for engine application |
| • | A vacuum leak between the EGR valve and the intake manifold |
| • | Signs of external leakage usually indicated by carbon buildup around the mating surfaces of the components or an audible exhaust noise |
| • | Restrictions in the passages or EGR valve caused by carbon deposits or casting flash |
| • | Leaks or restrictions at the MAP sensor |
| | Important: Restrictions can cause excessive back pressure and low engine vacuum.
|
| • | Mechanical failure in the engine such as worn piston rings, camshaft or incorrect timing belt installation--Refer to
Symptoms - Engine Mechanical
. |
- If all conditions test normal, replace the EGR valve.
Repair Instructions
Perform the
Diagnostic Repair Verification
after completing the diagnostic procedure.
Exhaust Gas Recirculation Valve Replacement
