
ENGINE - 2GR-FE ENGINEEG-133
15. Fail-safe
When the ECM detects a malfunction, the ECM stops or controls the engine according to the date already
stored in the memory.
Fail-safe Chart
DTC No.Fail-safe OperationFail-safe Deactivation Conditions
P0031, P0032,
P0051, P0052ECM turns off air-fuel ratio sensor heater.Ignition switch OFF.
P0037, P0038,
P0057, P0058ECM turns off heated oxygen sensor heater.Ignition switch OFF.
P0100, P0102,
P0103Ignition timing is calculated from engine speed
and throttle angle.“Pass” condition detected.
P0110, P0112,
P0113Intake air temperature is fixed at 20C (68F).“Pass” condition detected.
P0115, P0117,
P0118Engine coolant temperature is fixed at 80C
(176
F).“Pass” condition detected.
P0120, P0121,
P0122, P0123,
P0220, P0222,
P0223, P0604,
P0606, P0607,
P0657, P2102,
P2103, P2111,
P2112, P2118,
P2119, P2135
If ETCS-i (Electronic Throttle Control
System-intelligent) has a malfunction, ECM
cuts off current to throttle control motor.
Throttle control valve returns to predetermined
opening angle (approximately 6.5
) by force of
return spring. ECM then adjusts engine output
by controlling fuel injection (intermittent
fuel-cut) and ignition timing in accordance with
accelerator pedal opening angel to enable
vehicle to continue driving at minimal speed. If
accelerator pedal is depressed firmly and
slowly, vehicle can be driven slowly. If
accelerator pedal is depressed quickly, vehicle
may speed up and slow down erratically.If “Pass” condition is detected and
then the ignition switch is turned
OFF, fail-safe operation will stop
and system will return to normal
operating conditions.
P0327, P0328,
P0332, P0333Max. timing retardation.Ignition switch OFF.
P0351, P0352,
P0353, P0354,
P0355, P0356
Fuel is cut.“Pass” condition detected.
P2120, P2121,
P2122, P2123,
P2125, P2127,
P2128, P2138
Accelerator pedal position sensor has two (main
and sub) sensor circuits. If a malfunction occurs
in either of sensor circuits, ECM detects
abnormal signal voltage difference between two
sensor circuits and switches into limp mode. In
limp mode, remaining circuit is used to calculate
accelerator pedal opening to allow vehicle to
continue driving. If both circuits malfunction,
ECM regards opening angle of accelerator pedal
to be fully closed. In this case, throttle valve will
remain closed as if engine is idling.
If “Pass” condition is detected and
then the ignition switch is turned
OFF, fail-safe operation will stop
and system will return to normal
operating conditions.

SUPPLEMENTAL RESTRAINT SYSTEM – AIRBAG SYSTEMRS–27
RS
• The center airbag sensor receives signals
from the deceleration sensor and the
electronic safing sensor built into the center
airbag sensor and the rear airbag sensor, and
determines whether or not the side airbag
and curtain shield airbag should be activated,
and diagnoses system malfunctions.
• The center airbag sensor sends the airbag
deployment signal to ECM through the CAN
to operate the fuel pump control.
(2) Deceleration sensor and ignition control circuit
• The deceleration sensor is built into the
center airbag sensor.
• The ignition control circuit performs
calculations based on the signal output from
the deceleration sensors of the center airbag
sensor and front airbag sensor. If the
calculated values are greater than the
specified values, it activates the deployment
operation.
(3) Safing sensor
The safing sensor is built into the center airbag
sensor. During a frontal collision, the sensor
turns on and outputs an ON signal to the center
airbag sensor if a deceleration rate greater than
the specified value is applied to the safing
sensor.
(4) Electronic safing sensor
The electronic safing sensor is built into the
center airbag sensor. During a side collision, the
sensor turns on and outputs an ON signal to the
center airbag sensor if a deceleration rate
greater than the specified value is applied to the
electronic safing sensor.
(5) Back-up power source
The back-up power source consists of a power
supply capacitor and a DC-DC converter. When
the power system does not function during a
collision, the power supply capacitor discharges
and supplies electric power to the system. The
DC-DC converter operates as a boosting
transformer when the battery voltage falls below
a predetermined level.
(6) Diagnostic circuit
This circuit constantly diagnoses system
malfunctions. When a malfunction is detected, it
lights up the SRS warning light on the telltale
light to inform the driver.
(7) Memory circuit
When a malfunction is detected in the diagnostic
circuit, it is coded and stored in the memory
circuit.

2AZ-FE ENGINE CONTROL SYSTEM – SFI SYSTEMES–61
ES
P0171 System Too Lean
(Bank 1)- Air induction system
- Injector blockage
- MAF meter
- ECT sensor
- Fuel pressure
- Gas leakage from
exhaust system
- Open or short in A/F
sensor (sensor 1)
circuit
- A/F sensor (sensor
1)
- A/F sensor heater
(sensor 1)
- Integration relay
(EFI MAIN relay)
- A/F sensor heater
and EFI MAIN relay
circuits
- PCV hose
connections
- PCV valve and hose
- ECMComes on DTC storedES-147
P0172 System Too Rich
(Bank 1)- Injector leakage or
blockage
- MAF meter
- ECT sensor
- Ignition system
- Fuel pressure
- Gas leakage from
exhaust system
- Open or short in A/F
sensor (sensor 1)
circuit
- A/F sensor (sensor
1)
- A/F sensor heater
(sensor 1)
- Integration relay
(EFI MAIN relay)
- A/F sensor heater
and EFI MAIN relay
circuits
- ECMComes on DTC storedES-147
P0220 Throttle / Pedal
Position Sensor /
Switch "B" Circuit- TP sensor (built into
throttle body)
- ECMComes on DTC storedES-114
P0222 Throttle / Pedal
Position Sensor /
Switch "B" Circuit
Low Input- TP sensor (built into
throttle body)
- Short in VTA2 circuit
- Open in VC circuit
- ECMComes on DTC storedES-114
P0223 Throttle / Pedal
Position Sensor /
Switch "B" Circuit
High Input- TP sensor (built into
throttle body)
- Open in VTA2 circuit
- Open in E2 circuit
- Short between VC
and VTA2 circuits
- ECMComes on DTC storedES-114 DTC No. Detection Item Trouble Areas MIL Memory See page

ES–622AZ-FE ENGINE CONTROL SYSTEM – SFI SYSTEM
ES
P0300 Random / Multiple
Cylinder Misfire
Detected- Open or short in
engine wire harness
- Connector
connection
- Vacuum hose
connection
- Ignition system
- Injector
- Fuel pressure
- MAF meter
- ECT sensor
- Compression
pressure
- Valve clearance
- Valve timing
- PCV valve and hose
- PCV hose
connections
- Air induction system
- ECMComes on/Blinks* DTC storedES-156
P0301 Cylinder 1 Misfire
Detected- Same as DTC
P0300Comes on/Blinks* DTC storedES-156
P0302 Cylinder 2 Misfire
Detected- Same as DTC
P0300Comes on/Blinks* DTC storedES-156
P0303 Cylinder 3 Misfire
Detected- Same as DTC
P0300Comes on/Blinks* DTC storedES-156
P0304 Cylinder 4 Misfire
Detected- Same as DTC
P0300Comes on/Blinks* DTC storedES-156
P0327 Knock Sensor 1
Circuit Low Input
(Bank 1 or Single
Sensor)- Short in knock
sensor circuit
- Knock sensor
- ECMComes on DTC storedES-168
P0328 Knock Sensor 1
Circuit High Input
(Bank 1 or Single
Sensor)- Open in knock
sensor circuit
- Knock sensor
- ECMComes on DTC storedES-168
P0335 Crankshaft Position
Sensor "A" Circuit- Open or short in
Crankshaft Position
(CKP) sensor circuit
- CKP sensor
- CKP sensor plate
- ECMComes on DTC storedES-172
P0339 Crankshaft Position
Sensor "A" Circuit
Intermittent- Same as DTC
P0335- DTC storedES-172
P0340 Camshaft Position
Sensor "A" Circuit
(Bank 1 or Single
Sensor)- Open or short in
Camshaft Position
(CMP) sensor circuit
- CMP sensor
- Camshaft
- Jumped tooth of
timing chain
- ECMComes on DTC storedES-178
P0351 Ignition Coil "A"
Primary / Secondary
Circuit- Ignition system
- Open or short in
IGF1 or IGT circuit (1
to 4) between ignition
coil with igniter and
ECM
- No. 1 to No. 4
ignition coils with
igniters
- ECMComes on DTC storedES-183 DTC No. Detection Item Trouble Areas MIL Memory See page

2AZ-FE ENGINE CONTROL SYSTEM – SFI SYSTEMES–63
ES
P0352 Ignition Coil "B"
Primary / Secondary
Circuit- Same as DTC
P0351Comes on DTC storedES-183
P0353 Ignition Coil "C"
Primary / Secondary
Circuit- Same as DTC
P0351Comes on DTC storedES-183
P0354 Ignition Coil "D"
Primary / Secondary
Circuit- Same as DTC
P0351Comes on DTC storedES-183
P0420 Catalyst System
Efficiency Below
Threshold (Bank 1)- Front exhaust pipe
(with Three-Way
Catalytic Converter)
- Gas leakage from
exhaust system
- A/F sensor (sensor
1)
- HO2 sensor (sensor
2)Comes on DTC storedES-191
P043E Evaporative Emission
System Reference
Orifice Clog Up- Canister pump
module (Reference
orifice, leak detection
pump, vent valve)
- Connector/wire
harness (Canister
pump module - ECM)
- EVAP system hose
(pipe from air inlet
port to canister pump
module, canister
filter, fuel tank vent
hose)
- ECMComes on DTC storedES-198
P043F Evaporative Emission
System Reference
Orifice High Flow- Same as DTC
P043EComes on DTC storedES-198
P0441 Evaporative Emission
Control System
Incorrect Purge Flow- Purge VSV
- Connector/wire
harness (Purge VSV
- ECM)
- Canister pump
module
- Leakage from EVAP
system
- Leakage from EVAP
line (Purge VSV -
Intake manifold)
- ECMComes on DTC storedES-203
P0450 Evaporative Emission
Control System
Pressure Sensor /
Switch- Canister pump
module
- EVAP system hose
(pipe from air inlet
port to canister pump
module, canister
filter, fuel tank vent
hose)
- ECMComes on DTC storedES-210 DTC No. Detection Item Trouble Areas MIL Memory See page

2AZ-FE ENGINE CONTROL SYSTEM – SFI SYSTEMES–65
ES
P050A Cold Start Idle Air
Control System
Performance- Throttle body
assembly
- MAF meter
- Air induction system
- PCV hose
connections
- VVT system
- Air cleaner filter
element
- ECMComes on DTC storedES-237
P050B Cold Start Ignition
Timing Performance- Same as DTC
P050AComes on DTC storedES-237
P0516 Battery Temperature
Sensor Circuit Low- Battery current
sensor
- Short in battery
current sensor
- ECM- DTC storedES-243
P0517 Battery Temperature
Sensor Circuit High- Battery current
sensor
- Open in battery
current sensor
- ECM- DTC storedES-243
P0560 System Voltage - Open in back up
power source circuit
- Battery
- Battery terminals
- EFI MAIN fuse
- ECMComes on DTC storedES-245
P0604 Internal Control
Module Random
Access Memory
(RAM) Error- ECM Comes on DTC storedES-249
P0606 ECM / PCM
Processor- ECM Comes on DTC storedES-249
P0607 Control Module
Performance- ECM Comes on DTC storedES-249
P0617 Starter Relay Circuit
High- Park/Neutral
Position (PNP) switch
- ST relay circuit
- Ignition switch
- ECMComes on DTC storedES-251
P0630 VIN not Programmed
or Mismatch - ECM /
PCM- ECM Comes on DTC storedES-256
P0657 Actuator Supply
Voltage Circuit /
Open- ECM Comes on DTC storedES-249
P0724 Brake Switch "B"
Circuit High- Short in stop light
switch circuit
- Stop light switch
- ECMComes on DTC storedES-258
P1550 Battery Current
Sensor Circuit- Short in battery
current sensor circuit
- Battery current
sensor
- ECM- DTC storedES-261
P1551 Battery Current
Sensor Circuit Low- Short in battery
current sensor circuit
- Battery current
sensor
- ECM- DTC storedES-261 DTC No. Detection Item Trouble Areas MIL Memory See page

2AZ-FE ENGINE CONTROL SYSTEM – SFI SYSTEMES–93
ES
DESCRIPTION
The Mass Air Flow (MAF) meter is a sensor that measures the amount of air flowing through the throttle
valve.
The ECM uses this information to determine the fuel injection time and to provide the appropriate air-fuel
ratio.
Inside the MAF meter, there is a heated platinum wire which is exposed to the flow of intake air.
By applying a specific electrical current to the wire, the ECM heats it to a given temperature. The flow of
incoming air cools both the wire and an internal thermistor, affecting their resistance. To maintain a
constant current value, the ECM varies the voltage applied to these components in the MAF meter. The
voltage level is proportional to the airflow through the sensor, and the ECM uses it to calculate the intake
air volume.
The circuit is constructed so that the platinum hot wire and the temperature sensor create a bridge circuit,
and the power transistor is controlled so that the potentials of A and B remain equal to maintain the
predetermined temperature.
HINT:
When any of these DTCs are set, the ECM enters fail-safe mode. During fail-safe mode, the ignition
timing is calculated by the ECM, according to the engine RPM and throttle valve position. Fail-safe mode
continues until a pass condition is detected.
DTC P0100 Mass or Volume Air Flow Circuit
DTC P0102 Mass or Volume Air Flow Circuit Low Input
DTC P0103 Mass or Volume Air Flow Circuit High Input
DTC No. DTC Detection Conditions Trouble Areas
P0100MAF meter voltage less than 0.2 V, or more than 4.9 V for 3
seconds
(1 trip detection logic)• Open or short in MAF meter circuit
• MAF meter
•ECM
P0102MAF meter voltage less than 0.2 V for 3 seconds
(1 trip detection logic)• Open or short in MAF meter circuit
• MAF meter
•ECM
P0103MAF meter voltage more than 4.9 V for 3 seconds
(1 trip detection logic)• Open or short in MAF meter circuit
• MAF meter
•ECM
A140749E02