SFI SYSTEM, Diagnostic DTC:P2237, P2238, P2239, P2240, P2241, P2242, P2252, P2253, P2255, P2256

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)
P2240	Oxygen (A/F) Sensor Pumping Current Circuit / Open (Bank 2 Sensor 1)
P2241	Oxygen (A/F) Sensor Pumping Current Circuit Low (Bank 2 Sensor 1)
P2242	Oxygen (A/F) Sensor Pumping Current Circuit High (Bank 2 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)
P2255	Oxygen (A/F) Sensor Reference Ground Circuit Low (Bank 2 Sensor 1)
P2256	Oxygen (A/F) Sensor Reference Ground Circuit High (Bank 2 Sensor 1)

CAUTION / NOTICE / HINT

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.

DESCRIPTION

Refer to DTC P2195 Click here.

DTC No.	DTC Detection Condition	Trouble Area
P2237 P2240	Open in 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 (bank 1, 2 sensor 1) circuit Air fuel ratio sensor ECM
P2238 P2241	Case 1: Condition (a) or (b) continues for 5.0 seconds or more (1 trip detection logic): (a) AF+ voltage is 0.5 V or less (b) (AF+) - (AF-) = 0.1 V or less Case 2: A/F sensor admittance: Less than 0.022 1/Ω (2 trip detection logic)	Open or short in air fuel ratio sensor (bank 1, 2 sensor 1) circuit Air fuel ratio sensor (bank 1, 2 sensor 1) ECM
P2239 P2242	AF+ voltage is more than 4.5 V for 5.0 seconds or more (2 trip detection logic)	Open or short in air fuel ratio sensor (bank 1, 2 sensor 1) circuit Air fuel ratio sensor (bank 1, 2 sensor 1) ECM
P2252 P2255	AF- voltage is 0.5 V or less for 5.0 seconds or more (2 trip detection logic)	Open or short in air fuel ratio sensor (bank 1, 2 sensor 1) circuit Air fuel ratio sensor (bank 1, 2 sensor 1) ECM
P2253 P2256	AF- voltage is more than 4.5 V for 5.0 seconds or more (2 trip detection logic)	Open or short in air fuel ratio sensor (bank 1, 2 sensor 1) circuit Air fuel ratio sensor (bank 1, 2 sensor 1) ECM

Tech Tips

DTC P2237, P2238, P2239, P2252 and P2253 indicate malfunctions related to the bank 1 air fuel ratio sensor circuit.
DTC P2240, P2241, P2242, P2255 and P2256 indicate malfunctions related to the bank 2 air fuel ratio sensor circuit.
Bank 1 refers to the bank that includes cylinder No. 1.
Bank 2 refers to the bank that includes cylinder No. 2.

WIRING DIAGRAM

Refer to DTC P2195 Click here.

INSPECTION PROCEDURE

Tech Tips

For use of the 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 and turn the tester on.
Warm up the engine at an engine speed of 2500 rpm for approximately 90 seconds.
Select the following menu items on the tester: Powertrain / Engine and ECT / Active Test / Control the Injection Volume for A/F Sensor.
Perform the Control the Injection Volume for A/F Sensor operation with the engine in an idling condition (press the RIGHT or LEFT button to change the fuel injection volume).

Monitor the voltage outputs of the air fuel ratio and heated oxygen sensors (AFS B1S1 and O2S B1S2 or AFS B2S1 and O2S B2S2) 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.

Standard voltage

Tester Display (Sensor)	Injection Volume	Status	Voltage
AFS B1S1 or AFS B2S1 (Air fuel ratio)	+25%	Rich	Less than 3.0
AFS B1S1 or AFS B2S1 (Air fuel ratio)	-12.5%	Lean	More than 3.35
O2S B1S2 or O2S B2S2 (Heated oxygen)	+25%	Rich	More than 0.55
O2S B1S2 or O2S B2S2 (Heated oxygen)	-12.5%	Lean	Less than 0.4

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			-
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 leakage from exhaust system (Air fuel ratio extremely lean or rich)

Following the Control the Injection Volume for A/F Sensor procedure enables technicians to check the graph of the voltage outputs of both the air fuel ratio and heated oxygen sensors.
The following A/F Control procedure enables the technician to check and graph the voltage output of both the heated oxygen sensors. To display the graph, select the following menu items on the tester: View / Line Graph.
Tech Tips
- 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.
- A low air fuel ratio sensor voltage could be caused by a rich air fuel mixture. Check for conditions that would cause the engine to run rich.
- A high air fuel ratio sensor voltage could be caused by a lean air fuel mixture. Check for conditions that would cause the engine to run lean.

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)

Bank 1

Tester Connection	Condition	Specified Condition
B20-1 (HA1A) - B2-2 (HA1A)	Always	Below 1 Ω
B20-3 (A1A+) - B2-22 (A1A+)	Always	Below 1 Ω
B20-4 (A1A-) - B2-30 (A1A-)	Always	Below 1 Ω

Bank 2

Tester Connection	Condition	Specified Condition
B19-1 (HA2A) - B2-1 (HA2A)	Always	Below 1 Ω
B19-3 (A2A+) - B2-23 (A2A+)	Always	Below 1 Ω
B19-4 (A2A-) - B2-31 (A2A-)	Always	Below 1 Ω

Standard resistance (Check for short)

Bank 1

Tester Connection	Condition	Specified Condition
B20-1 (HA1A) or B2-2 (HA1A) - Body ground	Always	10 kΩ or higher
B20-3 (A1A+) or B2-22 (A1A+) - Body ground	Always	10 kΩ or higher
B20-4 (A1A-) or B2-30 (A1A-) - Body ground	Always	10 kΩ or higher

Bank 2

Tester Connection	Condition	Specified Condition
B19-1 (HA2A) or B2-1 (HA2A) - Body ground	Always	10 kΩ or higher
B19-3 (A2A+) or B2-23 (A2A+) - Body ground	Always	10 kΩ or higher
B19-4 (AF-) or B2-31 (A2A-) - Body ground	Always	10 kΩ or higher

Reconnect the ECM connector.

REPAIR OR REPLACE HARNESS OR CONNECTOR

REPLACE AIR FUEL RATIO SENSOR
1. Replace the air fuel ratio sensor Click here.
NEXT
PERFORM CONFIRMATION DRIVING PATTERN
1. Drive the vehicle referring the Confirmation Driving Pattern on DTC P2195 Click here.
NEXT

CHECK WHETHER DTC OUTPUT RECURS

Connect the intelligent tester to the DLC3.
Turn the ignition switch on (IG).
Turn the tester on.
Select the following menu items: Powertrain / Engine and ECT / Trouble Codes / Pending.

Read pending DTCs.

Result

Result	Proceed to
No output	A
P2237, P2238, P2239, P2240, P2241, P2242, P2252, P2253, P2255 or P2256	B

REPLACE ECM Click here

END