P0402

P0402 Exhaust Gas Recirculation Flow Excessive Detected

CIRCUIT DESCRIPTION

DTC Detection Condition:

The EGR system recirculates exhaust gas, which is controlled to the proper quantity to suit the driving conditions, into the intake air mixture to slow down combustion, reduce the combustion temperature and reduce NOx emissions. The amount of EGR is regulated by the EGR vacuum modulator according to the engine load.

If even one of the following conditions is fulfilled, the VSV is turned ON by a signal from the ECM.

This results in atmospheric air acting on the EGR valve, closing the EGR valve and shutting off the exhaust gas (EGR cut-off). Under the following conditions, EGR is cut to maintain driveability.
- Before the engine is warmed up.
- During deceleration (throttle valve closed).
- Light engine load (amount of intake air very small).
- Engine racing.

Wiring Diagram:

SYSTEM CHECK DRIVING PATTERN

System Check Driving Pattern:

a. Connect the hand-held tester or OBD II scan tool to the DLC3.
b. Start and warm up the engine with all the accessories switched OFF.
c. Run the vehicle at 70 - 90 km/h (43 - 56 mph) for 3 minutes or more.
d. Idle the engine for about 2 minutes.
e. Do steps (c) and (d) again.
f. Check the READINESS TESTS mode on the hand-held tester or OBD II scan tool.

If COMPL is displayed and the MIL does not light up, the system is normal.
If INCMPL is displayed and the MIL does not light up, run the vehicle step (e) from some times and check it.

HINT:
INCMPL is displayed when either condition (1) or (2) exists.
1. The system check is incomplete.
2. There is a malfunction in the system.
If there is a malfunction in the system, the MIL will light up after steps (b) to (e) above are done (2 trip detection logic).

INSPECTION PROCEDURE

HINT: Read freeze frame data using hand-held tester or OBD II scan tool, as freeze frame data records the engine conditions when a malfunction is detected. When troubleshooting, it is useful for determining whether the vehicle was running or stopped, the engine was warmed up or not, the air-fuel ratio was lean or rich, etc. at the time of the malfunction.

Step 1:

Step 2 - 4:

Step 4(continued) - 5:

Hand-held tester

Step 1 - 2:

Step 2(continued) - 5:

OBD II scan tool (excluding hand-held tester)