Lexus IS250 IS220d GSE20 ALE20 4GR-FSE ENGINE CONTROL SYSTEM
CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P2A00 AND/OR P2A03)
INSPECT AIR FUEL RATIO SENSOR (HEATER RESISTANCE)
CHECK HARNESS AND CONNECTOR (A/F SENSOR - ECM)
PERFORM CONFIRMATION DRIVING PATTERN
CHECK WHETHER DTC OUTPUT RECURS (DTC P2A00 AND/OR P2A03)
PERFORM CONFIRMATION DRIVING PATTERN
CHECK WHETHER DTC OUTPUT RECURS (DTC P2A00 AND/OR P2A03)
DTC P2A00 A/F Sensor Circuit Slow Response (Bank 1 Sensor 1)
DTC P2A03 A/F Sensor Circuit Slow Response (Bank 2 Sensor 1)
DESCRIPTION
- HINT:
Refer to DTC P2195 .
DTC No. | DTC Detection Conditions | Trouble Area |
P2A00 P2A03 | Calculated value for air-fuel ratio (A/F) sensor response rate deterioration level is less than threshold | Open or short in A/F sensor circuit A/F sensor ECM |
WIRING DIAGRAM
Refer to DTC P2195 .
INSPECTION PROCEDURE
- HINT:
- Intelligent tester only:
- Malfunctioning areas can be identified by performing the Control the Injection Volume for A/F Sensor function provided in the Active Test. The Control the Injection Volume for A/F Sensor 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 Control the Injection Volume for A/F Sensor operation using the intelligent tester.
- HINT:
Tester Display (Sensor) | Injection Volume | Status | Voltage |
AFS B1 S1 or AFS B2 S1 (A/F) | +25 % | Rich | Less than 3.0 |
AFS B1 S1 or AFS B2 S1 (A/F) | -12.5 % | Lean | More than 3.35 |
O2S B1 S2 or O2S B2 S2 (HO2) | +25 % | Rich | More than 0.55 |
O2S B1 S2 or O2S B2 S2 (HO2) | -12.5 % | Lean | Less than 0.4 |
- NOTICE:
- 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.
Case | A/F Sensor (Sensor 1) Output Voltage | HO2 Sensor (Sensor 2) Output Voltage | Main Suspected Trouble Area | ||
1 | Injection Volume +25 % -12.5 % | ![]() | Injection Volume +25 % -12.5 % | ![]() | - |
Output Voltage More than 3.35 V Less than 3.0 V | ![]() | Output Voltage More than 0.55 V Less than 0.4 V | ![]() | ||
2 | Injection Volume +25 % -12.5 % | ![]() | Injection Volume +25 % -12.5 % | ![]() | A/F sensor A/F sensor heater A/F sensor circuit |
Output Voltage Almost no reaction | ![]() | Output Voltage More than 0.55 V Less than 0.4 V | ![]() | ||
3 | Injection Volume +25 % -12.5 % | ![]() | Injection Volume +25 % -12.5 % | ![]() | HO2 sensor HO2 sensor heater HO2 sensor circuit |
Output Voltage More than 3.35 V Less than 3.0 V | ![]() | Output Voltage Almost no reaction | ![]() | ||
4 | Injection volume +25 % -12.5 % | ![]() | Injection Volume +25 % -12.5 % | ![]() | Injector Fuel pressure Gas leakage from exhaust system (Air-fuel ratio extremely lean or rich) |
Output Voltage Almost no reaction | ![]() | Output Voltage Almost no reaction | ![]() |
- HINT:
1.CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P2A00 AND/OR P2A03) |
Connect the intelligent tester to the DLC3.
Turn the engine switch on (IG).
Turn the tester ON.
Enter the following menus: Power train / Engine / DTC.
Read DTCs.
- Result:
Display (DTC Output) Proceed to P2A00 and/or P2A03 A P2A00 and/or P2A03 and other DTCs B
- HINT:
- If any DTCs other than P2A00 or P2A03 are output, troubleshoot those DTCs first.
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A | |
2.INSPECT AIR FUEL RATIO SENSOR (HEATER RESISTANCE) |

Disconnect the E42 or E38 A/F sensor connector.
Measure the resistance of the A/F sensor connector.
- Standard resistance (Bank 1 sensor 1):
Tester Connection Condition Specified Condition HA1A (1) - +B (2) 20°C (68°F) 1.8 Ω to 3.4 Ω HA1A (1) - A1A- (4) - 10 kΩ or higher
- Standard resistance (Bank 2 sensor 1):
Tester Connection Condition Specified Condition HA2A (1) - +B (2) 20°C (68°F) 1.8 Ω to 3.4 Ω HA2A (1) - A2A- (4) - 10 kΩ or higher
Reconnect the A/F sensor connector.
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OK | |
3.CHECK HARNESS AND CONNECTOR (A/F SENSOR - ECM) |

Disconnect the E42 or E38 A/F sensor connector.
Turn the engine switch on (IG).
Measure the voltage between the +B terminal of the A/F sensor connector and body ground.
- Standard voltage:
Tester Connection Specified Condition +B (E42-2) - Body ground 9 to 14 V +B (E38-2) - Body ground 9 to 14 V
Turn the engine switch off.
Disconnect the E6 ECM connector.
Measure the resistance of the wire harness side connector.
- Standard resistance (Check for open):
Tester Connection Specified Condition HA1A (E42-1) - HA1A (E6-6) Below 1 Ω A1A+ (E42-3) - A1A+ (E6-18) Below 1 Ω A1A- (E42-4) - A1A- (E6-17) Below 1 Ω HA2A (E38-1) - HA2A (E6-4) Below 1 Ω A2A+ (E38-3) - A2A+ (E6-28) Below 1 Ω A2A- (E38-4) - A2A- (E6-27) Below 1 Ω
- Standard resistance (Check for short):
Tester Connection Specified Condition HA1A (E42-1) or HA1A (E6-6) - Body ground 10 kΩ or higher A1A+ (E42-3) or A1A+ (E6-18) - Body ground 10 kΩ or higher A1A- (E42-4) or A1A- (E6-17) - Body ground 10 kΩ or higher HA2A (E38-1) or HA2A (E6-4) - Body ground 10 kΩ or higher A2A+ (E38-3) or A2A+ (E6-28) - Body ground 10 kΩ or higher A2A- (E38-4) or A2A- (E6-27) - Body ground 10 kΩ or higher
Reconnect the ECM connector.
Reconnect the A/F sensor connector.
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OK | |
4.PERFORM CONFIRMATION DRIVING PATTERN |
NEXT | |
5.CHECK WHETHER DTC OUTPUT RECURS (DTC P2A00 AND/OR P2A03) |
Read DTCs using the intelligent tester.
Enter the following menus: Power train / Engine / DTC.
- Result:
Display (DTC Output) Proceed to P2A00 and/or P2A03 A No output B
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A | |
6.REPLACE AIR FUEL RATIO SENSOR |
NEXT | |
7.PERFORM CONFIRMATION DRIVING PATTERN |
NEXT | |
8.CHECK WHETHER DTC OUTPUT RECURS (DTC P2A00 AND/OR P2A03) |
Read DTCs using the intelligent tester.
Enter the following menus: Power train / Engine / DTC.
- Result:
Display (DTC Output) Proceed to No output A P2A00 and/or P2A03 B
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A | ||
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