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

Tech Tips


  • Although the DTC titles say 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.

These DTCs are stored when there is an open or short in the air fuel ratio sensor circuit, or if the air fuel ratio sensor output drops. To detect these problems, the voltage of the air fuel ratio sensor is monitored when the ignition switch is turned to ON, and the admittance (admittance is an electrical term that indicates the ease of flow of current) is checked while driving. If the voltage of the air fuel ratio sensor is between 0.6 V and 4.5 V, it is considered normal. If the voltage is out of the specified range, or the admittance is less than the standard value, the ECM determines that there is a malfunction in the air fuel ratio sensor. If the same malfunction is detected in the next driving cycle, the MIL is illuminated and a DTC is stored.

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, 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.

A01IPY3E43
A01IMZRE28
DTC No. DTC Detection Condition Trouble Area
P2237 An open in the circuit between terminals A1A+ and A1A- of the air fuel ratio sensor while the engine is running (2 trip detection logic).

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

  • Air fuel ratio sensor (sensor 1)

  • ECM
P2238

One of the following conditions is met (2 trip detection logic):


  • The air fuel ratio sensor output drops while the engine is running.

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

  • The voltage difference between terminals A1A+ and A1A- 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 The A1A+ voltage is higher 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 The 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 The A1A- voltage is higher 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 function provided in the Active Test. The Control the Injection Volume for A/F sensor function can help to determine whether the Air Fuel Ratio (A/F) sensor, Heated Oxygen (HO2) 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. Start the engine and turn the tester on.

  3. Warm up the engine at an engine speed of 2500 rpm for approximately 90 seconds.

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

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

  6. Monitor the output voltages of the A/F and HO2 sensors (AFS Voltage B1 S1 and O2S B1 S2) displayed on the tester.

Tech Tips


  • The Control the Injection Volume for A/F sensor operation decreases 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 B1 S1

(A/F)

 +25% Rich Below 3.1 V

AFS Voltage B1 S1

(A/F)

 -12.5% Lean Higher than 3.4 V

O2S B1 S2

(HO2)

 +25% Rich Higher than 0.55 V

O2S B1 S2

(HO2)

 -12.5% Lean Below 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 A/F Sensor (Sensor 1) Output Voltage HO2 Sensor (Sensor 2) Output Voltage Main Suspected Trouble Area
1 A01IUMQE01 A01IP5ME08 A01IUMQE01 A01IU6XE06 -
2 A01IUMQE01 A01ITIWE01 A01IUMQE01 A01IU6XE06

  • A/F sensor

  • A/F sensor heater

  • A/F sensor circuit
3 A01IUMQE01 A01IP5ME08 A01IUMQE01 A01ITIWE01

  • HO2 sensor

  • HO2 sensor heater

  • HO2 sensor circuit
4 A01IUMQE01 A01ITIWE01 A01IUMQE01 A01ITIWE01

  • Injector

  • Fuel pressure

  • Gas leak from exhaust system (Air fuel ratio extremely rich or lean)

Tech Tips

Read freeze frame data using the intelligent tester. Freeze frame data records the engine condition when malfunctions are detected. 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
      C28-3 (A1A+) - C68-103 (A1A+) Always Below 1 Ω
      C28-4 (A1A-) - C68-126 (A1A-) Always Below 1 Ω
      Standard Resistance (Check for Short)
      Tester Connection Condition Specified Condition
      C28-3 (A1A+) or C68-103 (A1A+) - Body ground Always 10 kΩ or higher
      C28-4 (A1A-) or C68-126 (A1A-) - Body ground Always 10 kΩ or higher

    4. Reconnect the ECM connector.

    5. Reconnect the air fuel ratio sensor connector.

      A01IPY3E43

    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 ignition switch to ON.

    3. Turn the tester on.

    4. Switch the ECM from normal mode to check mode Click here.

    5. Drive the vehicle referring to the Confirmation Driving Pattern Click here.


    NEXT

  4. CHECK WHETHER DTC OUTPUT RECURS (DTC P2237, P2238, P2239, P2252 OR P2253)


    1. Connect the intelligent tester to the DLC3.

    2. Turn the ignition switch to ON.

    3. Turn the tester on.

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

    5. Read the DTCs (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