Description

DATA TROUBLE CODE: P0402

SYSTEM: Exhaust Gas Recirculation Flow Excessive Detected

CIRCUIT DESCRIPTION





The Exhaust Gas Recirculation 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 Exhaust Gas Recirculation is regulated by the Exhaust Gas Recirculation Vacuum Modulator according to the engine load.
If even one of the following conditions is fulfilled, the Vacuum Switching Valve is turned ON by a signal from the Engine Control Module. This results in atmospheric air acting on the Exhaust Gas Recirculation Valve, closing the Exhaust Gas Recirculation Valve and shutting off the exhaust gas (Exhaust Gas Recirculation cut-off).

DIAGNOSTIC TROUBLE CODE DETECTING CONDITION
- Exhaust Gas Recirculation Gas Temperature Sensor value is high during Exhaust Gas Recirculation cut-off when engine is cold (Race engine at about 4,000 rpm without load so that vacuum is applied to port E) (2 trip detection logic).
- Exhaust Gas Recirculation Valve is always open (2 trip detection logic).

TROUBLE AREA
- Exhaust Gas Recirculation Valve stuck open.
- Exhaust Gas Recirculation Vacuum Switching Valve open malfunction.
- Open in Exhaust Gas Recirculation Vacuum Switching Valve circuit.
- Short in Exhaust Gas Recirculation Gas Temperature Sensor circuit.
- Engine Control Module.

SYSTEM CHECK DRIVING PATTERN





1. Connect the OBDII scan tool or LEXUS hand-held tester to the Data Link Connector 3.
2. Start and warm up the engine with all accessories switched OFF.
3. After the engine is warmed up, run the vehicle at 70 - 90 km/h (43 - 56 mph) for 3 minutes or more.
4. After driving, idle the engine for about 2 minutes.
5. After idling, check the "READINESS TESTS". If "COMPL" (test completed) is displayed, the system is normal. If "INCPL" is displayed, run the vehicle again and check it. If there is a malfunction in the system, "INCPL" (test incomplete) will be displayed, so perform troubleshooting.