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)

for Preparation Click here

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.

DESCRIPTION

These DTCs are set when there is an open or short in the A/F sensor circuit, or if A/F sensor output drops. To detect these problems, the voltage of the A/F sensor is monitored when the ignition switch is turned to the ON position, 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 A/F 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 will determine that there is a malfunction in the A/F sensor. If the same malfunction is detected in next driving cycle, the MIL will be illuminated and a DTC will be stored.
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, 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.

A140695E01


A107164E12


DTC No.
DTC Detection Conditions
Trouble Areas
P2237
Open in the circuit between terminals AF+ and AF- of the AF sensor while engine is running
(2 trip detection logic)
  1. Open or short in A/F sensor (sensor 1) circuit
  2. A/F sensor (sensor 1)
  3. ECM
P2238
Any of the following conditions are met
(2 trip detection logic)
  1. AF sensor output drops while engine is running.
  1. Voltage at terminal AF+ is 0.5 V or less.
  1. Voltage difference between terminals AF+ and AF- is 0.1 V or less.
  1. Open or short in A/F sensor (sensor 1) circuit
  2. A/F sensor (sensor 1)
  3. ECM
P2239
AF+ voltage more than 4.5 V
(2 trip detection logic)
  1. Open or short in A/F sensor (sensor 1) circuit
  2. A/F sensor (sensor 1)
  3. ECM
P2252
AF- voltage 0.5 V or less
(2 trip detection logic)
  1. Open or short in A/F sensor (sensor 1) circuit
  2. A/F sensor (sensor 1)
  3. ECM
P2253
AF- voltage more than 4.5 V
(2 trip detection logic)
  1. Open or short in A/F sensor (sensor 1) circuit
  2. A/F sensor (sensor 1)
  3. ECM

WIRING DIAGRAM


A134994E01


INSPECTION PROCEDURE

HINT:
Intelligent tester only:
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 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 2,500 rpm for approximately 90 seconds.
  4. On the tester, select the following menu items: Powertrain / Engine and ECT / Active Test / Control the Injection Volume for A/F Sensor.
  5. Perform the "Control the Injection Volume for A/F Sensor" operation with the engine idling (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 B1 S1 and O2S B1 S2) displayed on the tester.

HINT:
  1. 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 %.
  2. The sensors react in accordance with increases and decreases in the fuel injection volume.

Standard:

Tester Display
(Sensor)
Injection Volume
Status
Voltages
AFS B1 S1
(A/F)
+25 %
Rich
Less than 3.0
-12.5 %
Lean
More than 3.35
O2S B1 S2
(HO2)
+25 %
Rich
More than 0.5
-12.5 %
Lean
Less than 0.4

NOTICE:
The A/F sensor has an output delay of a few seconds and the HO2 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 Areas
1
Injection Volume
+25 %
-12.5 %
A103184
Injection Volume
+25 %
-12.5 %
A103184
-
Output Voltage
More than 3.35 V
Less than 3.0 V
A112626
Output Voltage
More than 0.5 V
Less than 0.4 V
A104057
2
Injection Volume
+25 %
-12.5 %
A103184
Injection Volume
+25 %
-12.5 %
A103184
  1. A/F sensor
  2. A/F sensor heater
  3. A/F sensor circuit
Output Voltage
Almost
no reaction
A103185
Output Voltage
More than 0.5 V
Less than 0.4 V
A104057
3
Injection Volume
+25 %
-12.5 %
A103184
Injection Volume
+25 %
-12.5 %
A103184
  1. HO2 sensor
  2. HO2 sensor heater
  3. HO2 sensor circuit
Output Voltage
More than 3.35 V
Less than 3.0 V
A112626
Output Voltage
Almost
no reaction
A103185
4
Injection volume
+25 %
-12.5 %
A103184
Injection Volume
+25 %
-12.5 %
A103184
  1. Injector
  2. Fuel pressure
  3. Gas leakage from exhaust system
    (Air-fuel ratio extremely lean or rich)
Output Voltage
Almost
no reaction
A103185
Output Voltage
Almost
no reaction
A103185
  1. Following the A/F CONTROL procedure enables technicians to check and graph the output voltages of both the A/F and HO2 sensors.
  2. To display the graph, select the following menu items on the tester: Powertrain / Engine and ECT / Active Test / Control the Injection Volume for A/F Sensor / Enter / View / AFS B1 S1 and 02S B1 S2.

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 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.
1.CHECK HARNESS AND CONNECTOR (A/F SENSOR - ECM)


    A127715E08
  1. Disconnect the C15 A/F sensor connector.

  1. Disconnect the C24 ECM connector.

  1. Measure the resistance between the terminals of the wire harness side connectors.

    Standard resistance (Check for open):
    Tester Connection
    Specified Condition
    A1A+ (C15-3) - A1A+ (C24-112)
    Below 1 Ω
    A1A- (C15-4) - A1A- (C24-113)
    Below 1 Ω

    Standard resistance (Check for short):
    Tester Connection
    Specified Condition
    A1A+ (C15-3) or A1A+ (C24-112) - Body ground
    10 kΩ or higher
    A1A- (C15-4) or A1A- (C24-113) - Body ground
    10 kΩ or higher
  1. Reconnect the ECM connector.



  1. Reconnect the A/F sensor connector.


    A140695E01



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK


2.REPLACE AIR-FUEL RATIO SENSOR

NEXT


3.CHECK WHETHER DTC OUTPUT RECURS
  1. Connect the intelligent tester to the DLC3.

  1. Turn the ignition switch to the ON position and turn the tester on.

  1. Clear the DTCs (Click here).

  1. Start the engine.

  1. Allow the engine to idle for 5 minutes or more.

  1. Select the following menu items: Powertrain / Engine and ECT / DTC.

  1. Read pending DTCs.

    Result:

    Display (DTC Output)
    Proceed to
    No output
    A
    P2237, P2238, P2239, P2252 or P2253
    B


B
REPLACE ECM
A

END