DTC    P2237    Oxygen (A/F) Sensor Pumping Current Circuit / Open (Bank 1 Sensor 1)

DTC    P2238    Oxygen (A/F) Sensor Pumping Current Circuit Low (Bank 1 Sensor 1)

DTC    P2239    Oxygen (A/F) Sensor Pumping Current Circuit High (Bank 1 Sensor 1)

DTC    P2252    Oxygen (A/F) Sensor Reference Ground Circuit Low (Bank 1 Sensor 1)

DTC    P2253    Oxygen (A/F) Sensor Reference Ground Circuit High (Bank 1 Sensor 1)

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DESCRIPTION

HINT:
  1. Although the DTC titles say oxygen sensor, these DTCs relate to the air fuel ratio (A/F) sensor.
  2. Sensor 1 refers to the sensor mounted in front of the Three-Way Catalytic Converter (TWC) and located near the engine assembly.

The A/F 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 A/F and regulates the fuel injection volume depending on the A/F and engine operating conditions. The voltage changes between 0.6 V and 4.5 V while the engine is running. If the A/F is lean, which means that the oxygen concentration in the exhaust gas is high, the voltage is high. If the A/F is rich, which means that the oxygen concentration in the exhaust gas is low, the voltage is low.

A200919E04


A171616E03


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)
  1. Open in air fuel ratio sensor (bank 1 sensor 1) circuit
  2. Air fuel ratio sensor (bank 1 sensor 1)
  3. ECM
P2238
Any of the following conditions are met
(2 trip detection logic)
  1. Air fuel ratio sensor output drops while engine is running.
  1. Voltage at terminal A1A+ is 0.5 V or less.
  1. Voltage difference between terminals A1A+ and A1A- is 0.1 V or less.
  1. Open or short in air fuel ratio sensor (bank 1 sensor 1) circuit
  2. Air fuel ratio sensor (bank 1 sensor 1)
  3. ECM
P2239
A1A+ voltage is more than 4.5 V
(2 trip detection logic)
  1. Open or short in air fuel ratio sensor (bank 1 sensor 1) circuit
  2. Air fuel ratio sensor (bank 1 sensor 1)
  3. ECM
P2252
A1A- voltage is 0.5 V or less
(2 trip detection logic)
  1. Open or short in air fuel ratio sensor (bank 1 sensor 1) circuit
  2. Air fuel ratio sensor (bank 1 sensor 1)
  3. ECM
P2253
A1A- voltage is more than 4.5 V
(2 trip detection logic)
  1. Open or short in air fuel ratio sensor (bank 1 sensor 1) circuit
  2. Air fuel ratio sensor (bank 1 sensor 1)
  3. ECM

WIRING DIAGRAM

Refer to DTC P2195 (Click here).

INSPECTION PROCEDURE

HINT:
Malfunctioning areas can be identified by performing the Control the Injection Volume for A/F Sensor 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. Start the engine.
  3. Turn the tester on.
  4. Warm up the engine at 2500 rpm for approximately 90 seconds.
  5. Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Injection Volume for A/F Sensor.
  6. Perform the Active Test operation with the engine in an idling condition (press the RIGHT or LEFT button to change the fuel injection volume).
  7. Monitor the output voltages of the air fuel ratio and heated oxygen sensors (AFS Voltage B1 S1 and O2S B1 S2) displayed on the tester.

HINT:
  1. The Control the Injection Volume for A/F Sensor Active Test lowers the fuel injection volume by 12.5% or increases the injection volume by 25%.
  2. 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
(air fuel ratio)
+25%
Rich
Less than 3.1 V
-12.5%
Lean
More than 3.4 V
O2S B1 S2
(heated oxygen)
+25%
Rich
 More than 0.55 V
-12.5%
Lean
Less than 0.4 V

NOTICE:
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
A150787E01
A151324E04
A150787E01
A150788E01
-
2
A150787E01
A150790E01
A150787E01
A150788E01
  1. Air fuel ratio sensor
  2. Air fuel ratio sensor heater
  3. Air fuel ratio sensor circuit
3
A150787E01
A151324E04
A150787E01
A150790E01
  1. Heated oxygen sensor
  2. Heated oxygen sensor heater
  3. Heated oxygen sensor circuit
4
A150787E01
A150790E01
A150787E01
A150790E01
  1. Fuel pressure
  2. Gas leaks from exhaust system (Air fuel ratio extremely lean or rich)
  1. Following the Control the Injection Volume for A/F Sensor procedure enables technicians to check and graph the voltage outputs of both the air fuel ratio and heated oxygen sensors.
  2. To display the graph, enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Injection Volume for A/F Sensor / AFS Voltage B1 S1 and O2S B1 S2; then press the view button.

NOTICE:
Inspect the fuses for circuits related to this system before performing the following inspection procedure.

HINT:
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 be helpful in determining whether the vehicle was running or stopped, whether the engine was warmed up or not, whether the air fuel ratio was lean or rich, as well as other data recorded at the time of a malfunction.

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

  1. Disconnect the air fuel ratio sensor connector.

  1. Disconnect the ECM connector.

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

    Standard Resistance (Check for Open):
    Tester Connection
    		Condition
    		Specified Condition
    C34-1 (HA1A) - B8-104 (HA1A)
    		Always
    		Below 1 Ω
    C34-3 (A1A+) - B8-103 (A1A+)
    		Always
    		Below 1 Ω
    C34-4 (A1A-) - B8-126 (A1A-)
    		Always
    		Below 1 Ω

    Standard Resistance (Check for Short):
    Tester Connection
    		Condition
    		Specified Condition
    C34-1 (HA1A) or B8-104 (HA1A) - Body ground
    		Always
    		10 kΩ or higher
    C34-3 (A1A+) or B8-103 (A1A+) - Body ground
    		Always
    		10 kΩ or higher
    C34-4 (A1A-) or B8-126 (A1A-) - Body ground
    		Always
    		10 kΩ or higher

  1. Reconnect the air fuel ratio sensor connector.

  1. Reconnect the ECM connector.



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK


2.REPLACE AIR FUEL RATIO SENSOR

  1. Replace the air fuel ratio sensor (Click here).


NEXT


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

  1. Connect the intelligent tester to the DLC3.

  1. Start the engine and warm it up (until the engine coolant temperature reaches 75°C (167°F)).

  1. Turn the tester on.

  1. Clear the DTCs (Click here).

  1. Switch the ECM from normal mode to check mode (Click here).

  1. Drive the vehicle for move than 10 minutes.

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

  1. Read the 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