SFI SYSTEM, Diagnostic DTC:P2238, P2239, P2241, P2242, P2252, P2253, P2255, P2256

DTC Code DTC Name
P2238 Oxygen (A/F) Sensor Pumping Current Circuit Low (Bank 1 Sensor 1)
P2239 Oxygen (A/F) Sensor Pumping Current Circuit High (Bank 1 Sensor 1)
P2241 Oxygen (A/F) Sensor Pumping Current Circuit Low (Bank 2 Sensor 1)
P2242 Oxygen (A/F) Sensor Pumping Current Circuit High (Bank 2 Sensor 1)
P2252 Oxygen (A/F) Sensor Reference Ground Circuit Low (Bank 1 Sensor 1)
P2253 Oxygen (A/F) Sensor Reference Ground Circuit High (Bank 1 Sensor 1)
P2255 Oxygen (A/F) Sensor Reference Ground Circuit Low (Bank 2 Sensor 1)
P2256 Oxygen (A/F) Sensor Reference Ground Circuit High (Bank 2 Sensor 1)

DESCRIPTION

The Air Fuel Ratio (A/F) sensor generates voltage* in response to the actual air fuel ratio. This sensor output voltage provide feedback to the ECM. The ECM uses the feedback to control the air fuel ratio. Using the sensor output voltage, the ECM determines the deviation from the stoichiometric air fuel ratio, and regulates the injection time. If the A/F sensor is malfunctioning, the ECM is unable to control the air fuel ratio accurately. The A/F sensor is equipped with a heater which heats the zirconia element. The heater is also controlled by the ECM. When the intake air volume is low (the temperature of the exhaust gas is low), a current flows to the heater to heat the sensor to facilitate the detection of accurate oxygen concentration. The A/F sensor is a planar type. Compared to the conventional type, the sensor and heater portions are narrower. The heat of the heater is conducted to the zirconia element through the alumina, accelerating sensor activation. To obtain a high purification rate of carbon monoxide (CO), hydrocarbon (HC) and nitrogen oxide (NOx) in the exhaust gas, a Three-Way Catalytic Converter (TWC) is used. The TWC is most efficient when the air fuel ratio is maintained near the stoichiometric air fuel ratio.

Tech Tips

*: The voltage value changes inside the ECM only.

A01J3C4E04
DTC No. DTC Detection Condition Trouble Area

P2238

P2241

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

Tech Tips

Main trouble area


  • Open in A/F sensor circuit

Condition (a) continues for 5.0 sec. or more:

(a) A1A+ voltage is 0.5 V or less

  • Open or short in A/F sensor circuit

  • A/F sensor

  • A/F sensor heater

  • A/F relay

  • A/F sensor heater and A/F relay circuit

  • ECM

Condition (a) continues for 5.0 sec. or more:

(a) (A1A+) - (A1A-) = 0.1 V or less

P2239

P2242

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

(2 trip detection logic)

Tech Tips

Main trouble area


  • Short in A/F sensor circuit

Condition (a) continues for 5.0 sec. or more:

(a) A1A+ voltage is greater than 4.5 V

  • Open or short in A/F sensor circuit

  • A/F sensor

  • A/F sensor heater

  • A/F relay

  • A/F sensor heater and A/F relay circuit

  • ECM

Condition (a) continues for 5.0 sec. or more:

(a) (A1A+) - (A1A-) = greater than 0.8 V

P2252

P2255

Condition (a) continues for 5.0 sec. or more:

(a) A1A- voltage is 0.5 V or less

(2 trip detection logic)

  • Open or short in A/F sensor circuit

  • A/F sensor

  • A/F sensor heater

  • A/F relay

  • A/F sensor heater and A/F relay circuit

  • ECM

P2253

P2256

Condition (a) continues for 5.0 sec. or more:

(a) A1A- voltage is greater than 4.5 V

Tech Tips


  • DTCs P2238, P2239, P2252 and P2253 indicate malfunctions related to bank 1 A/F sensor circuit.

  • DTCs P2241, P2242, P2255 and P2256 indicate malfunctions related to bank 2 A/F sensor circuit.

  • Bank 1 refers to the bank that includes the No. 1 cylinder.

  • Bank 2 refers to the bank that includes the No. 2 cylinder.

MONITOR DESCRIPTION

The 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

A01J7P5E01

INSPECTION PROCEDURE

Tech Tips

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 the Active Test using the intelligent tester.

Tech Tips

"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).

Tech Tips


  • 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%.


  • 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 V

AFS B1S1 or AFS B2S1

(A/F)

 -12.5% Lean More than 3.35 V

O2S B1S2 or O2S B2S2

(heated oxygen sensor)

 +25% Rich More than 0.55 V

O2S B1S2 or O2S B2S2

(heated oxygen sensor)

 -12.5% Lean Less than 0.4 V

Note

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 Area
1

Injection volume

+25%

-12.5%

 A01J3SX

Injection volume

+25%

-12.5%

 A01J3SX -

Output voltage

More than 3.35 V

Less than 3.0 V

 A01J4D1

Output voltage

More than 0.55 V

Less than 0.4 V

 A01J4JK
2

Injection volume

+25%

-12.5%

 A01J3SX

Injection volume

+25%

-12.5%

 A01J3SX

  • A/F sensor

  • A/F sensor heater

  • A/F sensor circuit

Output voltage

Almost

no reaction

 A01J6YA

Output voltage

More than 0.55 V

Less than 0.4 V

 A01J4JK
3

Injection volume

+25%

-12.5%

 A01J3SX

Injection volume

+25%

-12.5%

 A01J3SX

  • Heated oxygen sensor

  • Heated oxygen sensor heater

  • Heated oxygen sensor circuit

Output voltage

More than 3.35 V

Less than 3.0 V

 A01J4D1

Output voltage

Almost

no reaction

 A01J6YA
4

Injection volume

+25%

-12.5%

 A01J3SX

Injection volume

+25%

-12.5%

 A01J3SX

  • Injector

  • Fuel pressure

  • Gas leakage from exhaust system

    (air fuel ratio extremely lean or rich)

Output voltage

Almost

no reaction

 A01J6YA

Output voltage

Almost

no reaction

 A01J6YA

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.

Tech Tips


  • 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.

  • These DTCs are related to the A/F sensor.

  • These DTCs are recorded when A/F sensor has a malfunction, although the caption is heated oxygen sensor.

PROCEDURE


  1. INSPECT AIR FUEL RATIO SENSOR (HEATER RESISTANCE)

    A01J3IUE37

    1. Disconnect the A30 and A31 A/F sensor connectors.

    2. Measure the resistance of the A/F sensor.

      Standard resistance
      Bank 1 Sensor 1
      Tester Connection Condition Specified Condition
      1 (HA1A) - 2 (+B) 20°C (68°F) 1.8 to 3.4 Ω
      1 (HA1A) - 4 (A1A-) - 10 kΩ or higher
      Bank 1 Sensor 1
      Tester Connection Condition Specified Condition
      1 (HA2A) - 2 (+B) 20°C (68°F) 1.8 to 3.4 Ω
      1 (HA2A) - 4 (A2A-) - 10 kΩ or higher

    NG

    REPLACE AIR FUEL RATIO SENSOR

    OK

  2. INSPECT A/F RELAY (Marking: A/F)

    A01J4ZME30

    1. Remove the relay from the engine room relay block.

    2. 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 A/F RELAY

    OK

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

    A01J68SE02

    1. Disconnect the A30 and A31 A/F sensor connectors.

    2. Disconnect the E16 ECM connector.

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

      Standard resistance
      Bank 1 Sensor 1
      Tester Connection Specified Condition
      A30-1 (HA1A) - E16-2 (HA1A) Below 1 Ω
      A30-3 (A1A+) - E16-22 (A1A+) Below 1 Ω
      A30-4 (A1A-) - E16-30 (A1A-) Below 1 Ω
      A30-1 (HA1A) or E16-2 (HA1A) - Body ground 10 kΩ or higher
      A30-3 (A1A+) or E16-22 (A1A+) - Body ground 10 kΩ or higher
      A30-4 (A1A-) or E16-30 (A1A-) - Body ground 10 kΩ or higher
      Bank 2 Sensor 1
      Tester Connection Specified Condition
      A31-1 (HA2A) - E16-1 (HA2A) Below 1 Ω
      A31-3 (A2A) - E16-23 (A2A+) Below 1 Ω
      A31-4 (A2A-) - E16-31 (A2A-) Below 1 Ω
      A31-1 (HA2A) or E16-1 (HA2A) - Body ground 10 kΩ or higher
      A31-3 (A2A+) or E16-23 (A2A+) - Body ground 10 kΩ or higher
      A31-4 (A2A-) or E16-31 (A2A-) - Body ground 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS AND CONNECTOR

    OK

    REPLACE ECM