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 P2241 Oxygen (A/F) Sensor Pumping Current Circuit Low (Bank 2 Sensor 1)

### DTC P2242 Oxygen (A/F) Sensor Pumping Current Circuit High (Bank 2 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)

### DTC P2255 Oxygen (A/F) Sensor Reference Ground Circuit Low (Bank 2 Sensor 1)

### DTC P2256 Oxygen (A/F) Sensor Reference Ground Circuit High (Bank 2 Sensor 1)

## for Preparation Click here

## DESCRIPTION

Refer to DTC P2195 (Click here).

DTC No. | DTC Detection Condition | Trouble Area

P2238
P2241

A/F sensor circuit low (bank 1 sensor 1)

HINT:

  Main trouble area

1. Open in A/F sensor circuit

Condition (a) continues for 5.0 sec. or more:
(a) AF+ voltage is 0.5 V or less

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

Condition (a) continues for 5.0 sec. or more: (b) (AF+) - (AF-) = 0.1 V or less

P2239
P2242

A/F sensor circuit high (bank 1 sensor 1)
(2 trip detection logic)

HINT:

  Main trouble area

1. Short in A/F sensor circuit

Condition (a) continues for 5.0 sec. or more:
AF+ voltage is greater than 4.5 V

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

Condition (a) continues for 5.0 sec. or more: (b) (AF+) - (AF-) = greater than 0.8 V

P2252
P2255

Condition (a) continues for 5.0 sec. or more:
AF- voltage is 0.5 V or less
(2 trip detection logic)

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

P2253 P2256 | Condition (a) continues for 5.0 sec. or more: AF- voltage is greater than 4.5 V

HINT:

1. DTCs P2238, P2239, P2252 and P2253 indicate malfunctions related to bank 1 A/F sensor circuit.
2. DTCs P2241, P2242, P2255 and P2256 indicate malfunctions related to bank 2 A/F sensor circuit.
3. Bank 1 refers to the bank that includes the No. 1 cylinder.
4. Bank 2 refers to the bank that includes the No. 2 cylinder.

## MONITOR DESCRIPTION

The Air-fuel Ratio (A/F) sensor varies its output voltage in proportion to the air-fuel ratio. If the A/F sensor impedance (alternating current resistance) or output voltage deviates greatly from the standard range, the ECM determines that there is an open or short malfunction in the A/F sensor circuit.

## WIRING DIAGRAM

Refer to DTC P2195 (Click here).

## INSPECTION PROCEDURE

HINT:

  Intelligent tester only:

  Malfunctioning areas can be found by performing the Active Test "Control the injection volume for A/F sensor" operation. The "Control the injection volume for A/F sensor" 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:

  "Control the injection volume for A/F sensor" is an Active Test which changes the injection volume to -12.5% or +25%.

(1) Control the intelligent tester to the DLC3.
(2) Start the engine and turn the tester ON.
(3) Warm up the engine by running the engine at 2,500 rpm for approximately 90 seconds.
(4) Enter the following menus on the intelligent tester: Powertrain / Engine and ECT / Active Test / Control the injection volume for A/F sensor.
(5) Enter the following monitor items: AFS B1S1 and O2S B1S2 or AFS B2S1 and O2S B2S2.
(6) Perform the "Control the injection volume for A/F sensor" operation with the engine in an idling condition (press the right or left button).

HINT:

1. The "Control the injection volume for A/F sensor" 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 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 (heated oxygen sensor) | +25% | Rich | More than 0.55
  O2S B1S2 or O2S B2S2 (heated oxygen sensor) | -12.5% | Lean | Less than 0.4

NOTICE:

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

Case | A/F Sensor (Sensor 1) Output Voltage | Heated Oxygen 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. Heated oxygen sensor
2. Heated oxygen sensor heater
3. Heated oxygen 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 |

The following A/F control procedure enables technician to check and graph the output voltages of both the A/F sensor and heated oxygen sensor.

HINT:

1. Read freeze frame data using the intelligent tester. Freeze frame data records the engine conditions when a malfunction is detected. When troubleshooting, freeze frame data can help determine if the vehicle was running or stopped, 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. These DTCs are related to the A/F sensor.
3. These DTCs are recorded when A/F sensor has a malfunction, although the caption is heated oxygen sensor.

1.INSPECT AIR FUEL RATIO SENSOR (HEATER RESISTANCE)

1. Disconnect the A/F sensor connector.

1. Measure the resistance of the A/F 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-) | - | 10 kΩ or higher

| NG |

REPLACE AIR FUEL RATIO SENSOR

OK |

2.INSPECT RELAY (Marking: A/F)

1. Remove the A/F sensor heater 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 or A25 A/F sensor connector.

1. Disconnect the E6 ECM connector.

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

   Standard resistance:

     Tester Connection | Specified Condition
     A18-1 (HT) - E16-2 (HA1A) | Below 1 Ω
     A18-3 (AF+) - E16-22 (A1A+) | Below 1 Ω
     A18-4 (AF-) - E16-30 (A1A-) | Below 1 Ω
     A25-1 (HT) - E16-1 (HA2A) | Below 1 Ω
     A25-3 (AF+) - E16-23 (A2A+) | Below 1 Ω
     A25-4 (AF-) - E16-31 (A2A-) | Below 1 Ω
     A18-1 (HT) or E16-2 (HA1A) - Body ground | 10 kΩ or higher
     A18-3 (AF+) or E16-22 (A1A+) - Body ground | 10 kΩ or higher
     A18-4 (AF-) or E16-30 (A1A-) - Body ground | 10 kΩ or higher
     A25-1 (HT) or E16-1 (HA2A) - Body ground | 10 kΩ or higher
     A25-3 (AF+) or E16-23 (A2A+) - Body ground | 10 kΩ or higher
     A25-4 (AF-) or E16-31 (A2A-) - Body ground | 10 kΩ or higher

| NG |

REPAIR OR REPLACE HARNESS AND CONNECTOR

OK |

REPLACE ECM