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

Refer to DTC P2195 Click here.

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) AF+ 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:

(b) (AF+) - (AF-) = 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:

AF+ voltage is greater than 4.5 V


  • Open or short in A/F sensor circuit

  • A/F sensor

  • A/F sensor heater

  • A/F heater relay

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

  • 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)


  • 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:

AF- 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 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

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 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

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

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 Areas
1

Injection volume

+25%

-12.5%

A01DUZ5

Injection volume

+25%

-12.5%

A01DUZ5 -

Output voltage

More than 3.35 V

Less than 3.0 V

A01DW5S

Output voltage

More than 0.55 V

Less than 0.4 V

A01DVNA
2

Injection volume

+25%

-12.5%

A01DUZ5

Injection volume

+25%

-12.5%

A01DUZ5
  • A/F sensor

  • A/F sensor heater

  • A/F sensor circuit

Output voltage

Almost

no reaction

A01E300

Output voltage

More than 0.55 V

Less than 0.4 V

A01DVNA
3

Injection volume

+25%

-12.5%

A01DUZ5

Injection volume

+25%

-12.5%

A01DUZ5
  • Heated oxygen sensor

  • Heated oxygen sensor heater

  • Heated oxygen sensor circuit

Output voltage

More than 3.35 V

Less than 3.0 V

A01DW5S

Output voltage

Almost

no reaction

A01E300
4

Injection volume

+25%

-12.5%

A01DUZ5

Injection volume

+25%

-12.5%

A01DUZ5
  • Injector

  • Fuel pressure

  • Gas leakage from exhaust system

    (air-fuel ratio extremely lean or rich)

Output voltage

Almost

no reaction

A01E300

Output voltage

Almost

no reaction

A01E300

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)

    A01E2SYE37

    1. Disconnect the A/F sensor connector.

    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
      Standard resistance (Bank 2 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
    OK
  2. INSPECT RELAY (Marking: A/F)

    A01DVNZE30

    1. Remove the A/F sensor heater 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
    OK
  3. CHECK WIRE HARNESS (A/F SENSOR - ECM)

    A01E33RE07

    1. Disconnect the A18 or A25 A/F sensor connector.

    2. Disconnect the E6 ECM connector.

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

      Standard resistance (Bank 1 Sensor 1)
      Tester Connection Specified Condition
      A18-1 (HA1A) - E16-2 (HA1A) Below 1 Ω
      A18-3 (A1A+) - E16-22 (A1A+) Below 1 Ω
      A18-4 (A1A-) - E16-30 (A1A-) Below 1 Ω
      A18-1 (HA1A) or E16-2 (HA1A) - Body ground 10 kΩ or higher
      A18-3 (A1A+) or E16-22 (A1A+) - Body ground 10 kΩ or higher
      A18-4 (A1A-) or E16-30 (A1A-) - Body ground 10 kΩ or higher
      Standard resistance (Bank 2 Sensor 1)
      Tester Connection Specified Condition
      A25-1 (HA2A) - E16-1 (HA2A) Below 1 Ω
      A25-3 (A2A+) - E16-23 (A2A+) Below 1 Ω
      A25-4 (A2A-) - E16-31 (A2A-) Below 1 Ω
      A25-1 (HA2A) or E16-1 (HA2A) - Body ground 10 kΩ or higher
      A25-3 (A2A+) or E16-23 (A2A+) - Body ground 10 kΩ or higher
      A25-4 (A2A-) or E16-31 (A2A-) - Body ground 10 kΩ or higher
      A01E25OE04

    NG
    OK