GSIC - Global Service Information Center

### DTC P2238 Oxygen (A/F) Sensor Pumping Current Circuit Low (Bank 1 Sensor 1)

### DTC P2239 Oxygen (A/F) Sensor Pumping Current Circuit High (Bank 1 Sensor 1)

### DTC P2252 Oxygen (A/F) Sensor Reference Ground Circuit Low (Bank 1 Sensor 1)

### DTC P2253 Oxygen (A/F) Sensor Reference Ground Circuit High (Bank 1 Sensor 1)

## for Preparation Click here

## DESCRIPTION

HINT:

  These DTCs are related to the A/F sensor.

Refer to DTC P2195 (Click here).

DTC No. | DTC Detection Condition | Trouble Area

P2238

1. Condition (a) or (b) continues for 5.0 seconds or more:
   (a) AF+ is 0.5 V or less
   (b) (AF+) - (AF-) is 0.1 V or less

1. A/F sensor admittance: Less than 0.022 1/Ω

1. Open or short in A/F sensor (sensor 1) circuit
2. A/F sensor (sensor 1)
3. A/F sensor heater
4. A/F relay
5. A/F sensor heater and relay circuits
6. ECM

P2239

1. Condition (a) or (b) continues for 5.0 seconds or more:
   (a) AF+ is more than 4.5 V
   (b) (AF+) - (AF-) is more than 0.8 V

1. Open or short in A/F sensor (sensor 1) circuit
2. A/F sensor (sensor 1)
3. A/F sensor heater
4. A/F relay
5. A/F sensor heater and relay circuits
6. ECM

P2252

AF- is 0.5 V or less for 5.0 seconds or more

1. Open or short in A/F sensor (sensor 1) circuit
2. A/F sensor (sensor 1)
3. A/F sensor heater
4. A/F relay
5. A/F sensor heater and relay circuits
6. ECM

P2253

AF- is more than 4.5 V for 5.0 seconds or more

1. Open or short in A/F sensor (sensor 1) circuit
2. A/F sensor (sensor 1)
3. A/F sensor heater
4. A/F relay
5. A/F sensor heater and relay circuits
6. ECM

## WIRING DIAGRAM

Refer to DTC P2195 (Click here).

## INSPECTION PROCEDURE

HINT:

  Intelligent tester only:

  Malfunctioning areas can be found by performing the Active Test / A/F Control operation. The A/F Control operation can determine if the A/F sensor, heated oxygen sensor or other potential trouble areas are malfunctioning or not.

(a) Perform Active Test using the intelligent tester.

HINT:

  The A/F Control operation lowers the injection volume by 12.5% or increases the injection volume by 25%.

1. Connect the intelligent tester to the DLC3.
2. Start the engine and turn the intelligent tester ON.
3. Warm up the engine by running the engine at 2,500 rpm for approximately 90 seconds.
4. On the intelligent tester, select the following menu items: Powertrain / Engine and ECT / Active Test /A/F control.
5. Select the following monitor items: AFS B1S1 and O2S B1S2.
6. Perform the A/F Control operation with the engine in an idling condition (press the right or left button).

HINT:

1. The A/F control operation lowers the fuel injection volume by 12.5% or increases the injection volume by 25%.

1. Each sensor reacts in accordance with increases and decreases in the fuel injection volume.

Standard:

  Tester Display (Sensor) | Injection Volume | Status | Voltage
  AFS B1S1 or AFS B1 S1 (A/F) | +25% | Rich | Less than 3.0 V
  AFS B1S1 or AFS B1 S1 (A/F) | -12.5% | Lean | More than 3.35 V
  O2S B1 S2 (HO2) | +25% | Rich | More than 0.55 V
  O2S B1 S2 (HO2) | -12.5% | Lean | Less than 0.4 V

NOTICE:

  The A/F sensor output has a few seconds of delay and the heated oxygen sensor output has about 20 seconds of delay at maximum.

Case | A/F Sensor (Sensor 1) Output Voltage | HO2 Sensor (Sensor 2) Output Voltage | Main Suspected Trouble Areas
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%

1. A/F sensor
2. A/F sensor heater
3. 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%

1. HO2 sensor
2. HO2 sensor heater
3. 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%

1. Injector
2. Fuel pressure
3. Gas leakage from exhaust system
   (Air-fuel ratio extremely lean or rich)

Output Voltage Almost no reaction |  | Output Voltage Almost no reaction |

1. The following A/F control procedure enables the technicians to check and graph the output voltages of both A/F Sensor and heated oxygen sensor.
2. To display the graph, select the following menu items on the tester: View / Line graph.

HINT:

1. Read freeze frame data using the intelligent tester. Freeze frame data records the engine conditions when malfunctions are detected. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, if the air-fuel ratio was lean or rich, and other data from the time the malfunction occurred.
2. A low A/F sensor voltage could be caused by a rich air-fuel mixture. Check the conditions that would cause the engine to run with the rich air-fuel mixture.
3. A high A/F sensor voltage could be caused by a lean air-fuel mixture. Check the conditions that would cause the engine to run with the lean air-fuel mixture.

1.INSPECT AIR FUEL RATIO SENSOR (HEATER RESISTANCE)

1. Disconnect the A18 sensor connector.

1. Measure the resistance of the sensor.

   Standard resistance:

     Tester Connection | Condition | Specified Condition
     1 (HT) - 2 (+B) | 20°C (68°F) | 1.8 to 3.4 Ω
     1 (HT) - 4 (AF-) | Always | 10 kΩ or higher

| NG |

REPLACE AIR FUEL RATIO SENSOR

OK |

2.INSPECT RELAY (Marking: A/F)

1. Remove the A/F relay from the engine room relay block.

1. Measure the resistance of the relay.

   Standard resistance:

     Tester Connection | Specified Condition
     3 - 5 | 10 kΩ or higher
     3 - 5 | Below 1 Ω (when battery voltage is applied to terminals 1 and 2)

| NG |

REPLACE RELAY

OK |

3.CHECK WIRE HARNESS (A/F SENSOR - ECM)

1. Disconnect the A18 A/F sensor connector.

1. Turn the E12 ECM connector.

1. Measure the resistance of the wire harness side connectors.

   Standard resistance:

     Tester Connection | Specified Condition
     A18-1 (HT) - E12-1 (HA1A) | Below 1 Ω
     A18-3 (AF+) - E12-21 (A1A+) | Below 1 Ω
     A18-4 (AF-) - E12-31 (A1A-) | Below 1 Ω
     A18-1 (HT) or E12-1 (HA1A) - Body ground | 10 kΩ or higher
     A18-3 (AF+) or E12-21 (A1A+) - Body ground | 10 kΩ or higher
     A18-4 (AF-) or E12-31 (A1A-) - Body ground | 10 kΩ or higher

| NG |

REPAIR OR REPLACE HARNESS AND CONNECTOR

OK |

REPLACE ECM