1Gr-Fe Engine Control. Dtc P2237 Oxygen (A/F) Sensor Pumping Current Circuit / Open (Bank 1 Sensor 1)

The air fuel ratio sensor generates voltage* that corresponds to the actual air fuel ratio. This sensor voltage is used to provide the ECM with feedback so that it can control the air fuel ratio. The ECM determines the deviation from the stoichiometric air fuel ratio level, and regulates the fuel injection duration. If the air fuel ratio sensor malfunctions, the ECM is unable to control the air fuel ratio accurately.
The air fuel ratio sensor is a planar type and integrated with the heater, which heats the solid electrolyte (zirconia element). This heater is controlled by the ECM. When the intake air volume is low (the exhaust gas temperature is low), a current flows into the heater to heat the sensor, in order to facilitate accurate oxygen concentration detection. In addition, the sensor and heater portions are a narrow type. The heat generated by the heater is conducted to the solid electrolyte through the alumina, and therefore sensor activation is accelerated.
In order to obtain a high purification rate of the carbon monoxide (CO), hydrocarbon (HC) and nitrogen oxide (NOx) components in the exhaust gas, a three-way catalytic converter is used. For the most efficient use of the three-way catalytic converter, the air fuel ratio must be precisely controlled so that it is always close to the stoichiometric level.
*: Value changes inside the ECM. Since the air fuel ratio sensor is a current output element, the current is converted into a voltage inside the ECM. Any measurements taken at the air fuel ratio sensor or ECM connectors will show a constant voltage.

Hilux. Tgn26, 36 Kun25, 26, 35, 36 Ggn25.1Gr-Fe Engine Control.Sfi System.
Dtc
P2237 Oxygen (A/F) Sensor Pumping Current Circuit / Open (Bank 1 Sensor 1)

DTC Code	DTC Detection Condition	Trouble Area
P2237 P2240	An open in the circuit between terminals A1A+/A2A+ and A1A-/A2A- of the air fuel ratio sensor while the engine is running (2 trip detection logic).	Open or short in air fuel ratio sensor (for bank 1, 2 sensor 1) circuit Air fuel ratio sensor (for bank 1, 2 sensor 1) ECM
P2238 P2241	Any of the following conditions are met (2 trip detection logic): The air fuel ratio sensor output drops while the engine is running. The voltage at terminal A1A+/A2A+ is 0.5 V or less. The voltage difference between terminals A1A+/A2A+ and A1A-/A2A- is 0.1 V or less.	Open or short in air fuel ratio sensor (for bank 1, 2 sensor 1) circuit Air fuel ratio sensor (for bank 1, 2 sensor 1) ECM
P2239 P2242	The A1A+/A2A+ voltage is higher than 4.5 V (2 trip detection logic).	Open or short in air fuel ratio sensor (for bank 1, 2 sensor 1) circuit Air fuel ratio sensor (for bank 1, 2 sensor 1) ECM
P2252 P2255	The A1A-/A2A- voltage is 0.5 V or less (2 trip detection logic).	Open or short in air fuel ratio sensor (for bank 1, 2 sensor 1) circuit Air fuel ratio sensor (for bank 1, 2 sensor 1) ECM
P2253 P2256	The A1A-/A2A- voltage is higher than 4.5 V (2 trip detection logic).	Open or short in air fuel ratio sensor (for bank 1, 2 sensor 1) circuit Air fuel ratio sensor (for bank 1, 2 sensor 1) ECM

MONITOR DESCRIPTION

These DTCs are stored when there is an open or short in the air fuel ratio sensor circuit, or if air fuel ratio sensor output drops. To detect these problems, the voltage of the air fuel ratio sensor is monitored when turning the ignition switch 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 will determine that there is a malfunction in the air fuel ratio sensor. If the same malfunction is detected in the next driving cycle, the MIL will be illuminated and a DTC will be stored.

CONFIRMATION DRIVING PATTERN

Connect the intelligent tester to the DLC3.
Turn the ignition switch to ON and turn the tester on.
Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure).
Turn the ignition switch off and wait for at least 30 seconds.
Turn the ignition switch to ON and turn the tester on.
Start the engine and wait for 5 minutes or more.
Enter the following menus: Powertrain / Engine and ECT / DTC.
Read the pending DTCs.
HINT:
1. If a pending DTC is output, the system is malfunctioning.
2. If a pending DTC is not output, perform the following procedure.
Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.
Input the DTC: P2237, P2238, P2239, P2240, P2241, P2242, P2252, P2253, P2255 or P2256.

Check the DTC judgment result.

Tester Display	Description
NORMAL	DTC judgment completed System normal
ABNORMAL	DTC judgment completed System abnormal
INCOMPLETE	DTC judgment not completed Perform driving pattern after confirming DTC enabling conditions
N/A	Unable to perform DTC judgment Number of DTCs which do not fulfill DTC preconditions has reached ECU memory limit

HINT:

If the judgment result shows NORMAL, the system is normal.
If the judgment result shows ABNORMAL, the system has a malfunction.
If the judgment result shows INCOMPLETE or N/A, perform the Confirmation Driving Pattern and the DTC judgment result again.

WIRING DIAGRAM

INSPECTION PROCEDURE

HINT:

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.
Refer to "Data List / Active Test" [AFS Voltage B1S1 and AFS Voltage B2S1] (HILUX_TGN26 RM000000PDN0NMX.html).
Bank 1 refers to the bank that includes No. 1 cylinder*.
*: The No. 1 cylinder is the cylinder which is farthest from the transmission.
Bank 2 refers to the bank that does not include No. 1 cylinder.
Sensor 1 refers to the sensor closest to the engine assembly.
Sensor 2 refers to the sensor farthest away from the engine assembly.

1.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:

Tester Connection	Condition	Specified Condition
C150-1 (HA1A) - C130-2 (HA1A)	Always	Below 1 Ω
C150-3 (A1A+) - C130-22 (A1A+)	Always	Below 1 Ω
C150-4 (A1A-) - C130-30 (A1A-)	Always	Below 1 Ω
C148-1 (HA2A) - C130-1 (HA2A)	Always	Below 1 Ω
C148-3 (A2A+) - C130-23 (A2A+)	Always	Below 1 Ω
C148-4 (A2A-) - C130-31 (A2A-)	Always	Below 1 Ω
C150-1 (HA1A) or C130-2 (HA1A) - Body ground	Always	10 kΩ or higher
C150-3 (A1A+) or C130-22 (A1A+) - Body ground	Always	10 kΩ or higher
C150-4 (A1A-) or C130-30 (A1A-) - Body ground	Always	10 kΩ or higher
C148-1 (HA2A) or C130-1 (HA2A) - Body ground	Always	10 kΩ or higher
C148-3 (A2A+) or C130-23 (A2A+) - Body ground	Always	10 kΩ or higher
C148-4 (A2A-) or C130-31 (A2A-) - Body ground	Always	10 kΩ or higher

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

2.REPLACE AIR FUEL RATIO SENSOR

Replace the air fuel ratio sensor (HILUX_TGN26 RM0000014HI00HX.html).

NEXT

3.CHECK WHETHER DTC OUTPUT RECURS

Connect the intelligent tester to the DLC3.

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

Clear the DTCs (HILUX_TGN26 RM000000PDK12JX.html).

Turn the ignition switch off and wait for at least 30 seconds.

Start the engine.

Drive the vehicle in accordance with the driving pattern described in the Confirmation Driving Pattern.

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

Read the pending DTCs.
Result
Result
Proceed to
DTC is not output
A
P2237, P2238, P2239, P2240, P2241, P2242, P2252, P2253, P2255 or P2256 is output
B

Result
Result	Proceed to
DTC is not output	A
P2237, P2238, P2239, P2240, P2241, P2242, P2252, P2253, P2255 or P2256 is output	B

REPLACE ECM (HILUX_TGN26 RM000000VW202SX.html)

END