SFI SYSTEM, Diagnostic DTC:P2237, P2238, P2239, P2252, P2253

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)
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)

DESCRIPTION

The air fuel ratio sensor, which is located between the exhaust manifold and catalyst, consists of alloyed metal elements and a heater.

Depending on the engine operating conditions, the heater heats the sensor elements to activate them. Battery voltage is applied to the heater and the sensor ground is controlled by the ECM using a duty ratio.

The sensor elements convert the oxygen concentration in the exhaust gas into voltage values to output. Based on the voltage, the ECM determines the air fuel ratio and regulates the fuel injection volume depending on the air fuel ratio and engine operating conditions. The voltage changes between 0.6 V and 4.5 V while the engine is running. If the air fuel ratio is lean, which means the oxygen concentration in the exhaust gas is high, the voltage is high. If the air fuel ratio is rich, which means the oxygen concentration in the exhaust gas is low, the voltage is low.

A003ST6E01
A003SEFE01
DTC No. DTC Detection Condition Trouble Area
P2237

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

(2 trip detection logic)

  • Open in air fuel ratio sensor (sensor 1) circuit

  • Air fuel ratio sensor (sensor 1)

  • ECM
P2238

Any of the following conditions are met (2 trip detection logic):


  • Air fuel ratio sensor output drops while engine is running.


  • Voltage at terminal A1A+ voltage is 0.5 V or less.


  • Voltage difference between terminals A1A+ and A1A- voltage is 0.1 V or less.

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

  • Air fuel ratio sensor (sensor 1)

  • ECM
P2239

A1A+ voltage is more than 4.5 V

(2 trip detection logic)

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

  • Air fuel ratio sensor (sensor 1)

  • ECM
P2252

A1A- voltage is 0.5 V or less

(2 trip detection logic)

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

  • Air fuel ratio sensor (sensor 1)

  • ECM
P2253

A1A- voltage is more than 4.5 V

(2 trip detection logic)

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

  • Air fuel ratio sensor (sensor 1)

  • ECM

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) and turn the tester on.

  3. Put the engine in inspection mode Click here.

  4. Start the engine.

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

  6. Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Injection Volume for A/F Sensor / All Data / AFS Voltage B1S1 and O2S B1S2.

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

  8. Monitor the output voltages of the air fuel ratio and heated oxygen sensors (AFS Voltage B1S1 and O2S B1S2) 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

(Air fuel ratio)

 +25% Rich Less than 3.1 V

AFS Voltage B1S1

(Air fuel ratio)

 -12.5% Lean More than 3.4 V

O2S B1S2

(Heated oxygen)

 +25% Rich More than 0.55 V

O2S B1S2

(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 A003UKNE12 A003UPYE01 -
2 A003S3KE06 A003UPYE01

  • Air fuel ratio sensor

  • Air fuel ratio sensor heater

  • Air fuel ratio sensor circuit
3 A003UKNE12 A003S3KE07

  • Heated oxygen sensor

  • Heated oxygen sensor heater

  • Heated oxygen sensor circuit

  • Exhaust gas leaks
4 A003S3KE06 A003S3KE06

  • Fuel pressure

  • Exhaust gas leaks

    (Air fuel ratio extremely lean or rich)

Tech Tips


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

  • Sensor 1 refers to the sensor closet to the engine assembly.

  • Sensor 2 refers to the sensor farthest away from the engine assembly.

  • 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.

    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
      B97-1 (HA1A) - B31-18 (HA1A) Always Below 1 Ω
      B97-3 (A1A+) - B31-103 (A1A+) Always Below 1 Ω
      B97-4 (A1A-) - B31-126 (A1A-) Always Below 1 Ω
      Standard Resistance (Check for Short)
      Tester Connection Condition Specified Condition
      B97-1 (HA1A) or B31-18 (HA1A) - Body ground Always 10 kΩ or higher
      B97-3 (A1A+) or B31-103 (A1A+) - Body ground Always 10 kΩ or higher
      B97-4 (A1A-) or B31-126 (A1A-) - Body ground Always 10 kΩ or higher

    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. PERFORM CONFIRMATION DRIVING PATTERN


    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. Put the engine in inspection mode Click here.

    6. Start the engine and wait for 5 minutes.


    NEXT

  4. CHECK WHETHER DTC OUTPUT RECURS


    1. Enter the following menus: Powertrain / Engine and ECT / DTC.

    2. Read the pending DTCs.

      Result
      Result Proceed to
      DTC is not output A
      DTC P2237, P2238, P2239, P2252 or P2253 is output B

    B

    REPLACE ECM Click here

    A

    END