Toyota Camry Manual page 1319

DI–292
DTC P0401
CIRCUIT DESCRIPTION
The EGR system recirculates exhaust gas, which is controlled to the proper quantity to suit the driving condi-
tions, into the intake air mixture to slow down combustion, reduce the combustion temperature and reduce
NOx emissions.
The lift amount of EGR valve is controlled by the vacuum which is regulated by the Duty–VSV operated by
the ECM. The lift amount of EGR valve is detected by the EGR valve position sensor which is mounted on
the EGR valve and it provides feedback to the ECM to control the lift amount of EGR valve in response to
engine operating conditions.
Under the following conditions, EGR is cut to maintain driveability.
D
Before the engine is warmed up
D
During deceleration (throttle valve closed)
D
Light engine load (amount of intake air very small)
D
Engine speed over 4,000 rpm
D
Engine idling
Mass Air Flow Meter
DTC No.
After engine is warmed up and run at 80 km/h (50 mph) for 3 to
5 min. EGR gas temperature sensor valve does not exceed
P0401
35°C (95°F) above ambient air temperature
(2 trip detection logic)
DIAGNOSTICS
Exhaust Gas Recirculation Flow
Insufficient Detected (Ex CA Spec.)
Engine Coolant
Temp. Sensor
DTC Detecting Condition
– ENGINE (1MZ–FE)
ECM
Vacuum
Control
Valve
Throttle Valve
Intake Air
Chamber
EGR Gas
Temp. Sensor
Crankshaft Position Sensor
D EGR valve (stuck closed)
D Open or short in EGR gas temp. sensor circuit
D EGR gas temp. sensor
D Open in VSV circuit for EGR
D VSV for EGR
D Vacuum control valve
D Vacuum hose disconnected or blocked
D ECM
Author :
VSV
for
EGR
EGR Valve
Position
Sensor
EGR Valve
Trouble Area
Date :
DI4DS–01
A00199
527