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

Refer to DTC P2195 Click here.

Tech Tips

Although the DTC titles refer to the 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.

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 circuit Air fuel ratio sensor 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 circuit Air fuel ratio sensor ECM
P2239	The A1A+ voltage is higher than 4.5 V (2 trip detection logic).	Open or short in air fuel ratio sensor circuit Air fuel ratio sensor ECM
P2252	The A1A- voltage is 0.5 V or less (2 trip detection logic).	Open or short in air fuel ratio sensor circuit Air fuel ratio sensor ECM
P2253	A1A- voltage is higher than 4.5 V (2 trip detection logic).	Open or short in air fuel ratio sensor circuit Air fuel ratio sensor ECM

WIRING DIAGRAM

Refer to DTC P2195 Click here.

INSPECTION PROCEDURE

Tech Tips

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 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.

Connect the intelligent tester to the DLC3.
Start the engine.
Turn the tester on.
Warm up the engine at an engine speed of 2500 rpm for approximately 90 seconds.
Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Injection Volume for A/F Sensor.
Perform the Active Test operation with the engine idling (press the RIGHT or LEFT button to change the fuel injection volume).
Monitor the output voltages of the air fuel ratio sensor and heated oxygen sensor (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 12.5%.
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 sensor)	+12.5%	Rich	Below 3.1 V
AFS Voltage B1S1 (Air fuel ratio sensor)	-12.5%	Lean	Higher than 3.4 V
O2S B1S2 (Heated oxygen sensor)	+12.5%	Rich	Higher than 0.55 V
O2S B1S2 (Heated oxygen sensor)	-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	Air Fuel Ratio Sensor Output Voltage	Heated Oxygen Sensor Output Voltage	Main Suspected Trouble Area
1			-
2			Air fuel ratio sensor Air fuel ratio sensor heater Air fuel ratio sensor circuit
3			Heated oxygen sensor Heated oxygen sensor heater Heated oxygen sensor circuit
4			Fuel pressure Gas leaks from exhaust system (air fuel ratio extremely lean or rich)

Performing the Control the Injection Volume for A/F Sensor enables technicians to check and graph the output voltage of both the air fuel ratio sensor and heated oxygen sensor.
To display the graph, enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Injection Volume for A/F Sensor / AFS Voltage B1S1 and O2S B1S2.

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

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

Disconnect the air fuel ratio sensor connector.
Disconnect the ECM connector.

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

Standard Resistance (Check for Open)

Tester Connection	Condition	Specified Condition
C56-3 (A1A+) - C63-7 (A1A+)	Always	Below 1 Ω
C56-4 (A1A-) - C63-1 (A1A-)	Always	Below 1 Ω

Standard Resistance (Check for Short)

Tester Connection	Condition	Specified Condition
C56-3 (A1A+) or C63-7 (A1A+) - Body ground	Always	10 kΩ or higher
C56-4 (A1A-) or C63-1 (A1A-) - Body ground	Always	10 kΩ or higher

Reconnect the ECM connector.
Reconnect the air fuel ratio sensor connector.

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

REPLACE AIR FUEL RATIO SENSOR
1. Replace the air fuel ratio sensor Click here.
NEXT

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

Connect the intelligent tester to the DLC3.
Turn the ignition switch to ON.
Turn the tester on.
Clear the DTCs Click here.
Switch the ECM from normal mode to check mode Click here.
Drive the vehicle according to Confirmation Driving Pattern Click here.
Enter the following menus: Powertrain / Engine and ECT / DTC.

Read the DTCs (Pending DTCs).

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

REPLACE ECM Click here

END