
ES–2542GR-FE ENGINE CONTROL SYSTEM – SFI SYSTEM
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Exhaust Camshaft Sensor Range Check (Low voltage):
Exhaust Camshaft Sensor Range Check (High voltage):
WIRING DIAGRAM
Refer to DTC P0335 (See page ES-222).
INSPECTION PROCEDURE
HINT:
Read freeze frame data using the intelligent tester. The ECM records vehicle and driving condition
information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data
can be helpful in determining whether the vehicle was running or stopped, whether the engine was
warmed up or not, whether the air-fuel ratio was lean or rich, as well as other data recorded at the time of
a malfunction.
(a) Disconnect the C21 or C20 VVT sensor connector.
(b) Measure the voltage according to the value(s) in the
table below.
Standard voltage
NG
OK
Exhaust camshaft sensor signal Less than 0.3 V
Exhaust camshaft sensor signal More than 4.7 V
1CHECK VVT SENSOR FOR EXHAUST CAMSHAFT (SENSOR POWER SOURCE)
A107149E59
Tester Connection Specified Condition
VC2 (C20-3) - Body ground 4.5 to 5.0 V
VC2 (C21-3) - Body ground 4.5 to 5.0 V
Go to step 7

ES–2582GR-FE ENGINE CONTROL SYSTEM – SFI SYSTEM
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MONITOR DESCRIPTION
The ECM uses the sensors mounted in front of and behind the three-way catalyst (TWC) to monitor its
efficiency. The first sensor, an Air Fuel ratio (A/F) sensor, sends pre-catalyst A/F ratio information to the
ECM. The second sensor, a heated oxygen sensor (O2S), sends post-catalyst information to the ECM.
The ECM compares these 2 signals to judge the efficiency of the catalyst and the catalyst's ability to store
oxygen. During normal operation, the TWC stores and releases oxygen as needed. The capacity to store
oxygen results in a low variation in the post-TWC exhaust stream.
If the catalyst is functioning normally, the waveform of the heated oxygen sensor slowly switches between
RICH and LEAN. If the catalyst is deteriorated, the waveform will alternate frequently between RICH and
LEAN. As the catalyst efficiency degrades, its ability to store oxygen is reduced and the catalyst output
becomes more variable. When running the monitor, the ECM compares sensor 1 signals (A/F sensor)
over a specific amount of time to determine catalyst efficiency. The ECM begins by calculating the signal
length for both sensors (for the rear oxygen sensor, the ECM uses the output voltage signal length). If the
oxygen sensor output voltage signal length is greater than the threshold (threshold is calculated based on
the A/F sensor signal length), the ECM concludes that the catalyst is malfunctioning. The ECM will turn on
the MIL and a DTC will be set.
HINT:
• Bank 1 refers to the bank that includes cylinder No. 1.
• Bank 2 refers to the bank that does not include cylinder No. 1.
• Sensor 1 refers to the sensor closest to the engine assembly.
• Sensor 2 refers to the sensor farthest away from the engine assembly.
MONITOR STRATEGY
DTC P0420Catalyst System Efficiency Below Threshold
(Bank 1)
DTC P0430Catalyst System Efficiency Below Threshold
(Bank 2)
DTC No. DTC Detection Condition Trouble Area
P0420Oxygen Storage Capacity (OSC) value is smaller than
standard value under active air-fuel ratio control (2 trip
detection logic)• Gas leakage from exhaust system
• A/F sensor (bank 1 sensor 1)
• HO2 sensor (bank 1 sensor 2)
• Exhaust manifold (TWC)
P0430OSC value is smaller than standard value under active
air-fuel ratio control (2 trip detection logic)• Gas leakage from exhaust system
• A/F sensor (bank 2 sensor 1)
• HO2 sensor (bank 2 sensor 2)
• Exhaust manifold (TWC)
Related DTCsP0420: Catalyst Deterioration
P0430: Catalyst Deterioration
Required Sensors / Components (Main) TWC
Required Sensors / Components (Related)A/F sensor, heated oxygen sensor, intake air temperature sensor, mass air flow
meter, crankshaft position sensor and engine coolant temperature sensor
Frequency of Operation Once per driving cycle
Duration Approximately 30 seconds
MIL Operation 2 driving cycles
Sequence of Operation None

2GR-FE ENGINE CONTROL SYSTEM – SFI SYSTEMES–259
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TYPICAL ENABLING CONDITIONS
TYPICAL MALFUNCTION THRESHOLDS
MONITOR RESULT
Refer to CHECKING MONITOR STATUS (See page ES-19).
CONDITIONING FOR SENSOR TESTING
HINT:
Perform the operation with the engine speeds and durations described below prior to checking the
waveforms of the A/F and HO2 sensors. This is in order to activate the sensors sufficiently to obtain the
appropriate inspection results.
The monitor will run whenever these DTCs are not
presentP0011, P0012 (VVT System 1-Advance, Retard), P0021, P0022 (VVT System 2-
Adavance, Retard), P0031, P0032, P0051, P0052 (A/F Sensor Heater Sensor 1),
P0037, P0038, P0057, P0058 (O2 Sensor heater Sensor 2), P0100, P0101, P0102,
P0103 (MAF Sensor), P0115, P0116, P0117, P0118 (ECT Sensor), P0120, P0121,
P0122, P0123, P0220, P0222, P0223 , P2135 (TP Sensor), P0125 (Insufficient ECT
for Closed Loop), P0136, P0156 (O2 Sensor 2), P0171,P0172 (Fuel System),
P0300, P0301, P0302, P0303, P0304, P0305, P0306 (Misfire), P0335 (CKP
Sensor), P0340 (CMP Sensor), P0351, P0352, P0353, P0354, P0355, P0356
(Ignitor), P0500 (VSS), P2196, P2198 (A/F Sensor (Rationality)), P2A00, P2A03 (A/
F Sensor (Slow Response))
Battery voltage 11 V or more
IAT -10
C (14F) or more
ECT 75
C (167F) or more
Atmospheric pressure 0.75 or more
Idle OFF
Engine RPM Less than 3200 rpm
A/F sensor Activated
Fuel system status Closed loop
Engine load 10 to 70%
All of the following conditions are met Conditions 1, 2 and 3
1. Mass air flow rate 5 to 60 g/sec.
2. Front catalyst temperature (estimated) 600 to 750
C (1112 to 1382F)
3. Rear catalyst temperature (estimated) 100 to 900
C (212 to 1652F)
Rear HO2S monitor Completed
Shift position 4th or more
Oxygen Storage Capacity (OSC) of catalyst Less than 0.046 g (0.000101 lb)

ES–2602GR-FE ENGINE CONTROL SYSTEM – SFI SYSTEM
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1. Connect the intelligent tester to the DLC3 (Procedure "A").
2. Start the engine and warm it up with all the accessories switched off, until the engine coolant
temperature stabilizes (Procedure "B").
3. Run the engine at an engine speed of between 2500 rpm and 3000 rpm for at least 3 minutes
(Procedure "C").
4. While running the engine at 3000 rpm for 2 seconds and at 2000 rpm for 2 seconds, check the
waveforms of the A/F and HO2 sensors using the tester (Procedure "D").
HINT:
• If either of the voltage outputs of the Air-Fuel Ratio (A/F) or Heated Oxygen (HO2) sensor does not
fluctuate, or either of the sensors makes a noise, the sensor may be malfunctioning.
• If the voltage outputs of both the sensors remain lean or rich, the air-fuel ratio may be extremely
lean or rich. In such cases, perform the following A/F CONTROL using the intelligent tester.
• If the Three-Way Catalytic Converter (TWC) has deteriorated, the HO2 sensor (located behind the
TWC) voltage output fluctuates up and down frequently, even under normal driving conditions
(active air-fuel ratio control is not performed).
A093766E27
A076893E08

2GR-FE ENGINE CONTROL SYSTEM – SFI SYSTEMES–261
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1. A/F CONTROL
HINT:
Intelligent tester only:
Malfunctioning areas can be identified by performing the A/F CONTROL function provided in the
ACTIVE TEST. The A/F CONTROL function can help to determine whether the Air-Fuel Ratio (A/F)
sensor, Heated Oxygen (HO2) sensor and other potential trouble areas are malfunctioning.
The following instructions describe how to conduct the A/F CONTROL operation using an intelligent
tester.
(a) Connect the intelligent tester to the DLC3.
(b) Start the engine and turn the tester on.
(c) Warm up the engine at an engine speed of 2500 rpm for approximately 90 seconds.
(d) On the tester, select the following menu items: DIAGNOSIS / ENHANCED OBD II / ACTIVE
TEST / A/F CONTROL.
(e) Perform the A/F CONTROL operation with the engine in an idling condition (press the RIGHT or
LEFT button to change the fuel injection volume).
(f) Monitor the voltage outputs of the A/F and HO2 sensors (AFS B1S1 and O2S B1S2 or AFS
B2S1 and O2S B2S2) displayed on the tester.
HINT:
• The A/F CONTROL operation lowers the fuel injection volume by 12.5% or increases the
injection volume by 25%.
• Each sensor reacts in accordance with increases and decreases in the fuel injection volume.
Standard voltage
CAUTION:
The Air-Fuel Ratio (A/F) sensor has an output delay of a few seconds and the Heated
Oxygen (HO2) sensor has a maximum output delay of approximately 20 seconds.
Tester Display (Sensor) Injection Volumes Status Voltages
AFS B1S1 or AFS B2S1 (A/F) +25% Rich Less than 3.0
AFS B1S1 or AFS B2S1 (A/F) -12.5% Lean More than 3.35
O2S B1S2 or O2S B2S2 (HO2) +25% Rich More than 0.55
O2S B1S2 or O2S B2S2 (HO2) -12.5% Lean Less than 0.4
CaseA/F Sensor (Sensor 1)
Output VoltageHO2 Sensor (Sensor 2)
Output VoltageMain Suspected
Trouble Area
1-

ES–2622GR-FE ENGINE CONTROL SYSTEM – SFI SYSTEM
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• Following the A/F CONTROL procedure enables technicians to check and graph the voltage
outputs of both the A/F and HO2 sensors.
• To display the graph, select the following menu items on the tester: DIAGNOSIS /
ENHANCED OBD II / ACTIVE TEST / A/F CONTROL / USER DATA / AFS B1S1 and O2S
B1S2 or AFS B2S1 and O2S B2S2. Press the YES button and then the ENTER button. Then
press the F4 button.
INSPECTION PROCEDURE
HINT:
Read freeze frame data using the intelligent tester. The ECM records vehicle and driving condition
information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data
can be helpful in determining whether the vehicle was running or stopped, whether the engine was
warmed up or not, whether the air-fuel ratio was lean or rich, as well as other data recorded at the time of
a malfunction.
(a) Connect the intelligent tester to the DLC3.
2• A/F sensor
• A/F sensor
heater
• A/F sensor
circuit
3• HO2 sensor
• HO2 sensor
heater
• HO2 sensor
circuit
4•Fuel pressure
• Gas leakage
from exhaust
system
(Air-fuel ratio
extremely lean
or rich)
1CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P0420 AND/OR P0430)
CaseA/F Sensor (Sensor 1)
Output VoltageHO2 Sensor (Sensor 2)
Output VoltageMain Suspected
Trouble Area

2GR-FE ENGINE CONTROL SYSTEM – SFI SYSTEMES–263
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(b) Turn the ignition switch to the ON position and turn the
tester on.
(c) Select the following menu items: DIAGNOSIS /
ENHANCED OBD II / DTC INFO / CURRENT CODES.
(d) Read the DTCs.
Result
HINT:
If any DTCs other than P0420 or P0430 are output,
troubleshoot those DTCs first.
B
A
(a) Connect the intelligent tester to the DLC3.
(b) Start the engine and turn the tester on.
(c) Warm up the engine at an engine speed of 2500 rpm for
approximately 90 seconds.
(d) Select the following menu items on the tester:
DIAGNOSIS / ENHANCED OBD II / ACTIVE TEST / A/F
CONTROL.
(e) Perform the A/F CONTROL operation with the engine in
an idling condition (press the RIGHT or LEFT button to
change the fuel injection volume).
(f) Monitor the voltage outputs of the A/F and HO2 sensors
(AFS B1S1 and O2S B1S2 or AFS B2S1 and O2S
B2S2) displayed on the tester.
HINT:
• The A/F CONTROL operation lowers the fuel injection
volume by 12.5% or increases the injection volume by
25%.
• Each sensor reacts in accordance with increases and
decreases in the fuel injection volume.
Standard voltage
Result
Display (DTC Output) Proceed to
P0420 and/or P0430 A
P0420 and/or P0430 and other DTCs B
GO TO DTC CHART (See page ES-56)
2PERFORM ACTIVE TEST BY INTELLIGENT TESTER (A/F CONTROL)
Tester Display (Sensor) Injection Volumes Status Voltages
AFS B1S1 or AFS B2S1 (A/F) +25% Rich Less than 3.0
AFS B1S1 or AFS B2S1 (A/F) -12.5% Lean More than 3.35
O2S B1S2 or O2S B2S2 (HO2) +25% Rich More than 0.55
O2S B1S2 or O2S B2S2 (HO2) -12.5% Lean Less than 0.4
Status AFS
B1S1 or AFS
B2S1Status O2S
B1S2 or O2S
B2S2A/F Condition and A/F and
HO2 Sensor ConditionsMisfires Suspected Trouble Areas Proceed to
Lean/Rich Lean/Rich Normal -• Three-Way Catalytic
Converter (TWC)
• Gas leakage from
exhaust systemA
Lean Lean/Rich A/F sensor malfunction - A/F sensor B

ES–2642GR-FE ENGINE CONTROL SYSTEM – SFI SYSTEM
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Lean: During A/F CONTROL, the A/F sensor output
voltage (AFS) is consistently more than 3.35 V, and the
HO2 sensor output voltage (O2S) is consistently less
than 0.4 V.
Rich: During A/F CONTROL, the AFS is consistently less
than 3.0 V, and the O2S is consistently more than 0.55 V.
Lean/Rich: During A/F CONTROL of the ACTIVE TEST,
the output voltage of the HO2 sensor alternates
correctly.
B
C
A
OK:
No gas leakage.
NG
OK
Rich Lean/Rich A/F sensor malfunction - A/F sensor B
Lean/Rich Lean HO2 sensor malfunction -• HO2 sensor
• Gas leakage from
exhaust systemC
Lean/Rich Rich HO2 sensor malfunction -• HO2 sensor
• Gas leakage from
exhaust systemC
Lean Lean Actual air-fuel ratio lean May occur• Extremely rich or lean
actual air-fuel ratio
• Gas leakage from
exhaust systemA
Rich Rich Actual air-fuel ratio rich -• Extremely rich or lean
actual air-fuel ratio
• Gas leakage from
exhaust systemA Status AFS
B1S1 or AFS
B2S1Status O2S
B1S2 or O2S
B2S2A/F Condition and A/F and
HO2 Sensor ConditionsMisfires Suspected Trouble Areas Proceed to
REPLACE AIR FUEL RATIO SENSOR
CHECK AND REPLACE HEATED OXYGEN
SENSOR, AND CHECK AND REPAIR
EXHAUST GAS LEAKAGE
3INSPECT FOR EXHAUST GAS LEAK
REPAIR OR REPLACE EXHAUST GAS
LEAKAGE POINT
REPLACE THREE-WAY CATALYTIC CONVERTER (EXHAUST MANIFOLD LH OR RH)