P0402

DTC P0402 Exhaust Gas Recirculation Flow Excessive Detected





CIRCUIT DESCRIPTION
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).





DETECTING CONDITION





WIRING DIAGRAM





SYSTEM CHECK DRIVING PATTERN
(1) Connect the OBD II scan tool or LEXUS hand-held tester to the DLC3.
(2) Start the engine and warm it up with all accessories switched OFF.
(3) Run the vehicle at 70 ~ 90 km/h (43 ~ 56 mph) for 3 min or more.
(4) Idle the engine for about 2 min.
(5) Do steps (3) and (4) again.
(6) Check the "READINESS TESTS" mode on the OBD II scan tool or LEXUS hand-held tester. 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 (5) for some times and check it.

HINT: "INCMPL" is displayed when either condition (a) or (b) exists.
(a) The system check is incomplete.
(b) There is a malfunction in the system.
If there is a malfunction in the system, the MIL will light up after steps (2) to (5) above are done again.

NOTICE: If the conditions in this test are not strictly followed, detection of the malfunction will not be possible.

INSPECTION PROCEDURE

Step 1:

Step 2:

Step 3:

Step 4:

Step 5:

LEXUS hand-held tester

Step 1:

Step 2:

Step 3:

Step 4:

Step 5:

OBD II scan tool (excluding LEXUS hand-held tester)