SFI SYSTEM (w/ EGR System), Diagnostic DTC:P2237, P2238, P2239, P2240, P2241, P2242, P2252, P2253, P2255, P2256

DTC Code DTC Name
P2237 Oxygen (A/F) Sensor Pumping Current Circuit / Open (Bank 1 Sensor 1)
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)
P2240 Oxygen (A/F) Sensor Pumping Current Circuit / Open (Bank 2 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

Tech Tips


  • Although the DTC titles include oxygen sensor, these DTCs relate to the air fuel ratio sensor.

  • Sensor 1 refers to the sensor mounted in front of the three-way catalytic converter and located near the engine assembly.

The air fuel ratio sensor generates voltage* that corresponds to the actual air fuel ratio. This sensor voltage is used to provide the ECM with feedback so that it can control the air fuel ratio. The ECM determines the deviation from the stoichiometric air fuel ratio level, and regulates the fuel injection duration. If the air fuel ratio sensor malfunctions, the ECM is unable to control the air fuel ratio accurately.

The air fuel ratio sensor is a planar type with an integrated heater, which heats the solid electrolyte (zirconia element). This heater is controlled by the ECM. When the intake air volume is low (the exhaust gas temperature is low), current flows to the heater to heat the sensor, in order to facilitate accurate oxygen concentration detection. In addition, the sensor and heater portions are narrower than the conventional type. The heat generated by the heater is conducted to the solid electrolyte through the alumina, therefore the sensor activation is accelerated.

A three-way catalytic converter is used in order to convert the carbon monoxide (CO), hydrocarbon (HC), and nitrogen oxide (NOx) into less harmful substances. To allow the three-way catalytic converter to function effectively, it is necessary to keep the air fuel ratio of the engine near the stoichiometric air fuel ratio.

*: Value changes inside the ECM. Since the air fuel ratio sensor uses a current output element, the current is converted to a voltage inside the ECM. Any measurements taken at the air fuel ratio sensor or ECM connectors will show a constant voltage.

A01NDNSE01
DTC No. DTC Detection Condition Trouble Area

P2237

P2240

Open in the circuit between terminals A1A+ (A2A-) and A1A- (A2A-) of the air fuel ratio sensor while engine running

(2 trip detection logic)

  • Open or short in air fuel ratio sensor (bank 1, 2 sensor 1) circuit

  • Air fuel ratio sensor (bank 1, 2 sensor 1)

  • ECM

P2238

P2241

  • Case 1:

Condition (a) or (b) continues for 5.0 seconds or more

(2 trip detection logic):

(a) Voltage at terminal A1A+ (A2A+) is 0.5 V or less

(b) Voltage difference between terminals A1A+ (A2A+) and A1A- (A2A-) is 0.1 V or less for 10 seconds


  • Case 2:

Air fuel ratio sensor admittance: Less than 0.015 1/Ω

(2 trip detection logic)

  • Open or short in air fuel ratio sensor (bank 1, 2 sensor 1) circuit

  • Air fuel ratio sensor (bank 1, 2 sensor 1)

  • ECM

P2239

P2242

A1A+ (A2A+) voltage is more than 4.5 V for 5.0 seconds or more

(2 trip detection logic)

  • Open or short in air fuel ratio sensor (bank 1, 2 sensor 1) circuit

  • Air fuel ratio sensor (bank 1, 2 sensor 1)

  • ECM

P2252

P2255

A1A- (A2A-) voltage is 0.5 V or less for 5.0 seconds or more

(2 trip detection logic)

  • Open or short in air fuel ratio sensor (bank 1, 2 sensor 1) circuit

  • Air fuel ratio sensor (bank 1, 2 sensor 1)

  • ECM

P2253

P2256

A1A- (A2A-) voltage is more than 4.5 V for 5.0 seconds or more

(2 trip detection logic)

  • Open or short in air fuel ratio sensor (bank 1, 2 sensor 1) circuit

  • Air fuel ratio sensor (bank 1, 2 sensor 1)

  • ECM

Tech Tips


  • DTCs P2237, P2238, P2239, P2252 and P2253 indicate malfunctions related to the bank 1 air fuel ratio sensor circuit.

  • DTCs P2240, P2241, P2242, P2255 and P2256 indicate malfunctions related to the bank 2 air fuel ratio sensor circuit.

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

  • Bank 2 refers to the bank that does not include cylinder No. 1.

CONFIRMATION DRIVING PATTERN

A01NGUFE07

  1. Connect the intelligent tester to the DLC3.

  2. Turn the power switch on (IG) and turn the tester on.

  3. Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure) Click here.

  4. Turn the power switch off.

  5. Turn the power switch on (IG) and turn the tester on [A].

  6. Put the engine in inspection mode Click here.

  7. Start the engine and wait 2 minutes.

  8. Enter the following menus: Powertrain / Engine and ECT / DTC / Pending [B].

  9. Read the pending DTC.

  10. If a pending DTC is output, the system is malfunctioning.

    Tech Tips

    If a pending DTC is not output, perform the following procedure.

  11. Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.

  12. Input the DTC: P2237, P2238, P2239, P2240, P2241, P2242, P2252, P2253, P2255 or P2256.

  13. Check the DTC judgment result.

    Tester Display Description
    NORMAL

    • DTC judgment completed

    • System normal
    ABNORMAL

    • DTC judgment completed

    • System abnormal
    INCOMPLETE

    • DTC judgment not completed

    • Perform driving pattern after confirming DTC enabling conditions
    UNKNOWN

    • Unable to perform DTC judgment

    • Number of DTCs which do not fulfill DTC preconditions has reached ECU memory limit

    Tech Tips


    • If the judgment result shows ABNORMAL, the system has a malfunction.

    • If the judgment result shows INCOMPLETE or UNKNOWN, idle the engine for 3 minutes and check the DTC judgment result again [C].

WIRING DIAGRAM

Refer to DTC P2195 Click here.

INSPECTION PROCEDURE

Tech Tips

Malfunctioning areas can be identified by performing the Control the Injection Volume for A/F Sensor in the Active Test. The Control the Injection Volume for A/F Sensor function can help to determine whether the air fuel ratio sensor, heated oxygen 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.


  1. Connect the intelligent tester to the DLC3.

  2. Turn the power switch on (IG).

  3. Turn the tester on.

  4. Put the engine in inspection mode Click here.

  5. Start the engine.

  6. Warm up the engine at 2500 rpm for approximately 90 seconds.

  7. Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Injection Volume for A/F Sensor.

  8. Perform Active Test operation with the engine idling (press the RIGHT or LEFT button to change the fuel injection volume).

  9. Monitor the output voltages of the air fuel ratio and heated oxygen sensors (AFS Voltage B1S1 and O2S B1S2 or AFS Voltage B2S1 and O2S B2S2) displayed on the tester.

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.

Tester Display

(Sensor)

 Injection Volume Status Voltage

AFS Voltage B1S1 or AFS Voltage B2S1

(Air fuel ratio)

 +25% Rich Less than 3.1 V

AFS Voltage B1S1 or AFS Voltage B2S1

(Air fuel ratio)

 -12.5% Lean More than 3.4 V

O2S B1S2 or O2S B2S2

(Heated oxygen)

 +25% Rich More than 0.55 V

O2S B1S2 or O2S B2S2

(Heated oxygen)

 -12.5% Lean Less than 0.4 V

Note

The air fuel ratio sensor has an output delay of a few seconds and the heated oxygen sensor has a maximum output delay of approximately 20 seconds.

Case

Air Fuel Ratio Sensor (Sensor 1)

Output Voltage

Heated Oxygen Sensor (Sensor 2)

Output Voltage

 Main Suspected Trouble Area
1 A01NFFXE12 A01NH0JE12 -
2 A01NE6JE06 A01NH0JE12

  • Air fuel ratio sensor

  • Air fuel ratio sensor heater

  • Air fuel ratio sensor circuit
3 A01NFFXE12 A01NE6JE07

  • Heated oxygen sensor

  • Heated oxygen sensor heater

  • Heated oxygen sensor circuit

  • Exhaust gas leaks
4 A01NE6JE06 A01NE6JE06

  • Fuel pressure

  • Exhaust gas leaks

    (Air fuel ratio extremely lean or rich)

Tech Tips

Read freeze frame data using the intelligent tester. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. 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.

PROCEDURE


  1. CHECK HARNESS AND CONNECTOR (AIR FUEL RATIO SENSOR - ECM)


    1. Disconnect the air fuel ratio sensor connector.

      A01NCUUE04

    2. Disconnect the ECM connector.

    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance (Check for Open)
      Tester Connection Condition Specified Condition
      D20-1 (HA1A) - D1-24 (HA1A) Always Below 1 Ω
      D20-3 (A1A+) - D1-100 (A1A+) Always Below 1 Ω
      D20-4 (A1A-) - D1-132 (A1A-) Always Below 1 Ω
      D19-1 (HA2A) - D1-22 (HA2A) Always Below 1 Ω
      D19-3 (A2A+) - D1-99 (A2A+) Always Below 1 Ω
      D19-4 (A2A-) - D1-131 (A2A-) Always Below 1 Ω
      Standard Resistance (Check for Short)
      Tester Connection Condition Specified Condition
      D20-1 (HA1A) or D1-24 (HA1A) - Body ground Always 10 kΩ or higher
      D20-3 (A1A+) or D1-100 (A1A+) - Body ground Always 10 kΩ or higher
      D20-4 (A1A-) or D1-132 (A1A-) - Body ground Always 10 kΩ or higher
      D19-1 (HA2A) or D1-22 (HA2A) - Body ground Always 10 kΩ or higher
      D19-3 (A2A+) or D1-99 (A2A+) - Body ground Always 10 kΩ or higher
      D19-4 (A2A-) or D1-131 (A2A-) - Body ground Always 10 kΩ or higher
      Text in Illustration
      *1

      Front view of wire harness connector

      (to Air Fuel Ratio Sensor)

      		 *2

      Front view of wire harness connector

      (to ECM)
      *3 Bank 1 *4 Bank 2

    4. Reconnect the air fuel ratio sensor connector.

    5. Reconnect the ECM connector.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (AIR FUEL RATIO SENSOR - ECM)

    OK

  2. REPLACE AIR FUEL RATIO SENSOR


    1. Replace the air fuel ratio sensor Click here.


    NEXT

  3. CHECK WHETHER DTC OUTPUT RECURS


    1. Connect the intelligent tester to the DLC3.

    2. Turn the power switch on (IG).

    3. Turn the tester on.

    4. Clear the DTCs Click here.

    5. Turn the power switch off.

    6. Turn the power switch on (IG) and turn the tester on.

    7. Put the engine in inspection mode Click here.

    8. Start the engine and warm it up.

    9. Drive the vehicle in accordance with the driving pattern described in the Confirmation Driving Pattern.

    10. Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.

    11. Input the DTC: P2237, P2238, P2239, P2240, P2241, P2242, P2252, P2253, P2255 or P2256.

    12. Check the DTC judgment result.

      Result
      Result Proceed to
      NORMAL (DTC is not output) A
      ABNORMAL (DTC P2237, P2238, P2239, P2240, P2241, P2242, P2252, P2253, P2255 or P2256 is output) B

    B

    REPLACE ECM Click here

    A

    END