p0401 TOYOTA CAMRY 2000 Service Repair Manual

DI±4
± DIAGNOSTICSENGINE (5S±FE)
239 Author: Date:

The diagnosis system operates in normal mode
during normal vehicle use. It also has a check mode
for technicians to simulate malfunction symptoms
and troubleshoot. Most DTCs use 2 trip detection
logic* to prevent erroneous detection, and ensure
thorough malfunction detection. By switching the
ECM to check mode when troubleshooting, the
technician can cause the MIL to light up for a mal-
function that is only detected once or momentarily.
(TOYOTA hand±held tester only)
(See page DI±3)

*2 trip detection logic: When a malfunction is first
detected, the malfunction is temporarily stored in
the ECM memory.(1st trip)
If the same malfunction is detected again during the second
drive test, this second detection causes the MIL to light up.(2nd
trip) (However, the IG switch must be turned OFF between the
1st trip and the 2nd trip.)

Freeze frame data:
Freeze frame data records the engine condition
when a misfire (DTCs P0300 ~ P0304) or fuel trim
malfunction (DTCs P0171, P0172) or other mal-
function (first malfunction only), is detected.
Because freeze frame data records the engine
conditions (fuel system, calculated load, engine
coolant temperature, fuel trim, engine speed, ve-
hicle speed, etc.) when the malfunction is detected,
when troubleshooting it is useful for determining
whether the vehicle was running or stopped, the en-
gine warmed up or not, the air±fuel ratio lean or rich,
etc. at the time of the malfunction.

Priorities for troubleshooting:
If troubleshooting priorities for multiple DTCs are given in the
applicable DTC chart, these should be followed.
If no instructions are given troubleshoot DTCs according to the
following priorities.
(1) DTCs other than fuel trim malfunction (DTCs
P0171, P0172), EGR (DTCs P0401, P0402), and
misfire (DTCs P0300 ~ P0304).
(2) Fuel trim malfunction (DTCs P0171, P0172), and
EGR (DTCs P0401, P0402).
(3) Misfire (DTCs P0300 ~ P0304).

DI±18
± DIAGNOSTICSENGINE (5S±FE)
253 Author: Date:
DTC No.
(See Page)Detection ItemTrouble AreaMIL*1Memory
P0340
(DI±103)Camshaft Position Sensor
Circuit Malfunction
Open or short in camshaft position sensor circuit
Camshaft position sensor
Distributor
Starter
ECM

P0401
(DI±105)Exhaust Gas Recirculation
Flow Insufficient Detected
EGR valve stuck closed
Open or short in VSV circuit for EGR
Vacuum or EGR hose disconnected
Manifold absolute pressure sensor
EGR VSV open or close malfunction
ECM

P0402
(DI±113)Exhaust Gas Recirculation
Flow Excessive Detected
EGR valve stuck open
Vacuum or EGR hose is connected to wrong post
Manifold absolute pressure sensor
ECM

*2
P0420
(DI±116)
Catalyst System Efficiency
Below Threshold
(Except California Spec.)Three±way catalytic converter
Open or short in heated oxygen sensor circuit
Heated oxygen sensor

*3
P0420
(DI±119)
Catalyst System Efficiency
Below Threshold
(Only for California Spec.)
Three±way catalystic converter
Open short in heated oxygen sensor (bank 1 sensor 2) circuit
Heated oxygen sensor (bank 1 sensor 2)
Open or short in A/F sensor circuit
A/F sensor

P0440
(DI±122)Evaporative Emission Control
System Malfunction
Vapor pressure sensor
Fuel tank cap incorrectly installed
Fuel tank cap cracked or damaged
Vacuum hose cracked, holed, blocked, damaged or
disconnected ((1) or (2) in fig. 1)
Hose or tube cracked, holed, damaged or loose seal
((3) in fig. 1)
Fuel tank cracked, holed or damaged
Charcoal canister cracked, holed or damaged
Fuel tank over fill check valve cracked or damaged

P0441
(DI±129)Evaporative Emission Control
System Incorrect Purge Flow
Open or short in VSV circuit for vapor pressure sensor
VSV for vapor pressure sensor
Open or short in vapor pressure sensor circuit
Vapor pressure sensor
O h t i VSV i it f EVAP

P0446
(DI±129)Evaporative Emission Control
System Vent Control
Malfunction
Open or short in VSV circuit for EVAP
VSV for EVAP
Vacuum hose cracks, hole, blocked, damaged or disconnected
((1), (4), (5) holed (6) and (7) in fig. 1)
Charcoal canister cracked, holed or damaged
Fuel tank over fill check valve cracked or damaged

P0450
(DI±142)Evaporative Emission Control
System Pressure Sensor
Malfunction
Open or short in vapor pressure sensor circuit
V

P0451
(DI±142)Evaporative Emission Control
System Pressure Sensor
(Range/performance)Vapor pressure sensor
ECM

*1: 


MIL lights up
*
2: Except California Specification vehicles
*
3: Only for California Specification vehicles

P25430
ECM
Throttle Body
EGR
Vacuum
Modulator EGR Valve
VSV
Exhaust Gas Throttle
Valve
u
± DIAGNOSTICSENGINE (5S±FE)
DI±105
340 Author: Date:
DTC P0401 Exhaust Gas Recirculation Flow Insufficient
Detected
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 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 driveabil-
ity.

Before engine is warmed up.

During deceleration (throttle valve closed).

Light engine load (amount of intake air very small).

Engine idling.

Engine speed over 4,400 rpm.

High engine load (amount of intake air very large).
DTC No.DTC Detecting ConditionTrouble Area
P0401
After engine is warmed up, intake manifold absolute pressure
is larger than value calculated by ECM while EGR system is
ON
(2 trip detection logic)

EGR valve stuck closed

Open or short in VSV circuit for EGR

Vacuum or EGR hose disconnected

Manifold absolute pressure sensor

VSV for EGR open or close malfunction

ECM
DI015±05

P20769
Vehicle Speed
60 ~ 80 km/h
(38 ~ 50 mph)
Idling
IG SW OFF
(1)(2)
Warm up
3 ~ 5 min.2 min.
3 ~ 5 min.Time (3)
(4)
(5)(6)
(7)
2 min.
± DIAGNOSTICSENGINE (5S±FE)
DI±107
342 Author: Date:
SYSTEM CHECK DRIVING PATTERN
(1) Connect the OBD II scan tool or TOYOTA hand±held tester to the DLC3.
(2) Start and warm up the engine with all accessories switched OFF.
(3) Run the vehicle at 60 ~ 80 km/h (38 ~ 50 mph) for 3 min. or more.
(4) Idle the engine for about 2 min.
(5) Do steps (3) and (4) again.
(6) Stop at safe place and turn the ignition switch OFF.
(7) Do steps (2) to (5) again.
(8) Check the READINESS TESTS mode on the OBD II scan tool or TOYOTA 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 again 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.
(2 trip detection logic)
INSPECTION PROCEDURE
HINT:

If DTC P0105 (Manifold Absolute Pressure/Barometric Pressure Circuit Malfunction), P0106 (Manifold
Absolute Pressure/Barometric Pressure Circuit Range/Performance Problem) and P0401 (Exhaust
Gas Recirculation Flow Insufficient Detected) are output simultaneously, perform troubleshooting of
DTC P0105 first.

If DTC P0401 (Exhaust Gas Recirculation Flow Insufficient Detected) and P0402 (Exhaust Gas Recir-
culation Flow Excessive Detected) are output simultaneously, perform troubleshooting of DTC P0402
first.

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

± DIAGNOSTICSENGINE (5S±FE)
DI±113
348 Author: Date:
DTC P0402 Exhaust Gas Recirculation Flow Excessive
Detected
CIRCUIT DESCRIPTION
Refer to DTC P0401 (Exhaust Gas Recirculation Flow Insufficient Detected) on page DI±105.
DTC No.DTC Detecting ConditionTrouble Area
P0402
After engine is warmed up, conditions (a) and (b) continue:
(a) Intake manifold absolute pressure is larger than value cal-
culated by ECM while EGR system is ON
(b) Misfiring is detected during idling
(2 trip detection logic)
EGR valve stuck open

Vacuum or EGR hose is connected to wrong post

Manifold absolute pressure sensor

ECM
WIRING DIAGRAM
Refer to DTC P0401 (Exhaust Gas Recirculation Flow Insufficient Detected) on DI±105.
SYSTEM CHECK DRIVING PATTEM
Refer to DTC P0401 (Exhaust Gas Recirculation Flow Insufficient Detected) on DI±105.
INSPECTION PROCEDURE
HINT:

If DTC P0105 (Manifold Absolute Pressure/Barometric Pressure Circuit Malfunction), P0106 (Manifold
Absolute Pressure/Barometric Pressure Circuit Range/Performance Problem) and P0402 (Exhaust
Gas Recirculation Flow Excessive Detected) are output simultaneously, perform troubleshooting of
DTC P0105 first.

If DTC P0401 (Exhaust Gas Recirculation Flow Insufficient Detected) and P0402 (Exhaust Gas Recir-
culation Flow Excessive Detected) are output simultaneously, perform troubleshooting of DTC P0402
first.

Read freeze frame data using TOYOTA hand±held tester or OBD II scan tool. Because freeze frame
records the engine conditions when the malfunction is detected, when troubleshooting it is useful for
determining whether the vehicle was running or stopped, the engine warmed up or not, the air±fuel
ratio lean or rich, etc. at the time of the malfunction.
1 Check connection of vacuum hose and EGR hose (See page EC±12).
NG Repair or replace.
OK
DI016±04

DI±198
± DIAGNOSTICSENGINE (1MZ±FE)
433 Author: Date:

The diagnosis system operates in normal mode
during normal vehicle use. It also has a check mode
for technicians to simulate malfunction symptoms
and troubleshoot. Most DTC use 2 trip detection
logic* to prevent erroneous detection, and ensure
thorough malfunction detection. By switching the
ECM to check mode when troubleshooting, the
technician can cause the MIL to light up for a mal-
function that is only detected once or momentarily
(TOYOTA hand±held tester only). (See page
DI±197)

*2 trip detection logic:
When a malfunction is first detected, the malfunc-
tion is temporarily stored in the ECM memory. (1st
trip)
If the same malfunction is detected again during the second
drive test, this second detection causes the MIL to light up. (2nd
trip) (However, the IG switch must be turned OFF between the
1st trip and the 2nd trip.).

Freeze frame data:
Freeze frame data records the engine condition
when a misfire (DTCs P0300 ~ P0306) or fuel trim
malfunction (DTCs P0171, P0172) or other mal-
function (first malfunction only), is detected.
Because freeze frame data records the engine
conditions (fuel system, calculated load, engine
coolant temperature, fuel trim, engine speed, ve-
hicle speed, etc.) when the malfunction is detected,
when troubleshooting it is useful for determining
whether the vehicle was running or stopped, the en-
gine warmed up or not, the air±fuel ratio lean or rich,
etc. at the time of the malfunction.

Priorities for troubleshooting:
If troubleshooting priorities for multiple DTC are given in the ap-
plicable DTC chart, these should be followed.
If no instructions are given troubleshoot DTC according to the
following priorities.
(1) DTC other than fuel trim malfunction (DTCs P0171,
P0172), EGR (DTCs P0401, P0402) and misfire
(DTCs P0300 ~ P0306).
(2) Fuel trim malfunction (DTCs P0171, P0172) and
EGR (DTCs P0401, P0402).
(3) Misfire (DTCs P0300 ~ P0306).

± DIAGNOSTICSENGINE (1MZ±FE)
DI±213
448 Author: Date:
DTC No.
(See Page)Detection ItemTrouble AreaMILMemory
P0300
(DI±276)Random/Multiple Cylinder
Misfire DetectedIgnition system
Injector
Fuel line pressure
EGR
P0301
P0302
P0303
P0304
P0305
P0306
(DI±276)Misfire Detected
± Cylinder 1
± Cylinder 2
± Cylinder 3
± Cylinder 4
± Cylinder 5
± Cylinder 6
EGR
Compression pressure
Valve clearance not to specification
Valve timing
Mass air flow meter
Engine coolant temp. sensor
Open or short engine wire
Connector connection
ECM
*2
P0325
(DI±283)Knock Sensor 1 Circuit
MalfunctionOpen or short in knock sensor 1 circuit
Knock sensor 1 (looseness)
ECM
*1
P0330
(DI±283)Knock Sensor 2 Circuit
MalfunctionOpen or short in knock sensor 2 circuit
Knock sensor 2 (looseness)
ECM
*1
P0335
(DI±287)Crankshaft Position Sensor
ºAº Circuit Malfunction
Open or short in crankshaft position sensor circuit
Crankshaft position sensor
Starter
ECM
*1
P0340
(DI±290)Camshaft Position Sensor
Circuit Malfunction
Open or short in camshaft position sensor circuit
Camshaft position sensor
Starter
ECM
*1
P0401
(DI±292)Exhaust Gas Recirculation
Flow Insufficient Detected
EGR valve (stuck closed)
Open or short in EGR gas temp. sensor circuit
EGR gas temp. sensor
Open in VSV circuit for EGR
VSV for EGR
Vacuum control valve
Vacuum hose disconnected or blocked
ECM
*1
P0402
(DI±302)Exhaust Gas Recirculation
Flow Excessive Detected
EGR valve stuck open
VSV for EGR open malfunction
Short in VSV circuit for EGR
Open or short in EGR valve position sensor circuit
EGR valve position sensor
ECM
*1
*3
P0420
(DI±305)Catalyst System Efficiency
Below Threshold
(Except California Spec.)Three±way catalytic converter
Open or short in heated oxygen sensor circuit
Heated oxygen sensor
*2
*4
P0420
(DI±308)Catalyst System Efficiency
Below Threshold
(Only for California Spec.)
Three±way catalytic converter
Open or short in heated oxygen sensor (bank 1, sensor 2)
circuit
Heated oxygen sensor (bank 1, sensor 2)
Open or short in A/F sensor (bank 1, 2 sensor 1) circuit
A/F sensor (bank 1, 2 sensor 1)
*2
*1: MIL lights up
*2: MIL lights up on U.S.A and Canadian specification vehicles
*3: Except California specification vehicles
*4: Only for California specification vehicle

A00199
ECM
Mass Air Flow MeterVSV
for
EGR
EGR Valve
Position
Sensor
EGR Valve EGR Gas
Temp. Sensor
Crankshaft Position Sensor Engine Coolant
Temp. SensorIntake Air
Chamber Throttle ValveVacuum
Control
Valve
DI±292
± DIAGNOSTICSENGINE (1MZ±FE)
527 Author: Date:
DTC P0401 Exhaust Gas Recirculation Flow
Insufficient Detected (Ex CA Spec.)
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.

Before the engine is warmed up

During deceleration (throttle valve closed)

Light engine load (amount of intake air very small)

Engine speed over 4,000 rpm

Engine idling
DTC No.DTC Detecting ConditionTrouble Area
P0401
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
35°C (95°F) above ambient air temperature
(2 trip detection logic)

EGR valve (stuck closed)

Open or short in EGR gas temp. sensor circuit

EGR gas temp. sensor

Open in VSV circuit for EGR

VSV for EGR

Vacuum control valve

Vacuum hose disconnected or blocked

ECM
DI4DS±01

DI±302
± DIAGNOSTICSENGINE (1MZ±FE)
537 Author: Date:
DTC P0402 Exhaust Gas Recirculation Flow
Excessive Detected (Ex CA Spec.)
CIRCUIT DESCRIPTION
Refer to DTC P0401 (Exhaust Gas Recirculation Flow Insufficient Detected) on page DI±292.
DTC No.DTC Detecting ConditionTrouble Area
P0402
When EGR cut±off, lift amount of EGR valve is
2.6 mm (0.1 in.) or more
(2 trip detection logic)

EGR valve stuck open

VSV for EGR open malfunction

Short in VSV circuit for EGR

Open or short in EGR valve position sensor circuit

EGR valve position sensor

ECM
See DTC P0401 (Exhaust Gas Recirculation Flow Insufficient Detected) on See page DI±292 for SYS-
TEM CHECK DRIVING PATTERN and WIRING DIAGRAM.
INSPECTION PROCEDURE
HINT:
Read freeze frame data using TOYOTA hand±held tester or OBD II scan tool. Because freeze frame records
the engine conditions when the malfunction is detected, when troubleshooting it is useful for determining
whether the vehicle was running or stopped, the engine warmed up or not, the air±fuel ratio lean or rich, etc.
at the time of the malfunction.
TOYOTA hand±held tester
1 Check connection and blockage of vacuum hose.
NG Repair or replace vacuum hose.
OK
2 Check VSV for EGR (See page DI±292, step 5).
OK Go to step 4.
NG
DI07X±06