SFI SYSTEM, Diagnostic DTC:P0037, P0038, P0057, P0058

DTC Code	DTC Name
P0037	Oxygen Sensor Heater Control Circuit Low (Bank 1 Sensor 2)
P0038	Oxygen Sensor Heater Control Circuit High (Bank 1 Sensor 2)
P0057	Oxygen Sensor Heater Control Circuit Low (Bank 2 Sensor 2)
P0058	Oxygen Sensor Heater Control Circuit High (Bank 2 Sensor 2)

DESCRIPTION

Refer to DTC P0136 Click here.

Tech Tips

When any of these DTCs are set, the ECM enters fail-safe mode. The ECM turns off the heated oxygen sensor (HO2S) heater in fail-safe mode. Fail-safe mode continues until the ignition switch is turned OFF.
The ECM uses a pulse width modulated control circuit to adjust current through the heater. The heated oxygen sensor heater circuit uses a relay on the +B side of the circuit.

DTC No.	DTC Detection Condition	Trouble Area
P0037 P0057	Heated oxygen sensor (HO2S) heater current less than 0.3 A (1 trip detection logic)	Open in heated oxygen sensor heater (bank 1, 2 sensor 2) circuit Heated oxygen sensor heater (bank 1, 2 sensor 2) Integration relay ECM
P0038 P0058	Heated oxygen sensor (HO2S) heater current more than 2 A (1 trip detection logic)	Short in heated oxygen sensor heater (bank 1, 2 sensor 2) circuit Heated oxygen sensor heater (bank 1, 2 sensor 2) Integration relay ECM

DTC No.

DTC Detection Condition

Trouble Area

P0037

P0057

Heated oxygen sensor (HO2S) heater current less than 0.3 A

(1 trip detection logic)

Open in heated oxygen sensor heater (bank 1, 2 sensor 2) circuit
Heated oxygen sensor heater (bank 1, 2 sensor 2)
Integration relay
ECM

P0038

P0058

Heated oxygen sensor (HO2S) heater current more than 2 A

(1 trip detection logic)

Short in heated oxygen sensor heater (bank 1, 2 sensor 2) circuit
Heated oxygen sensor heater (bank 1, 2 sensor 2)
Integration relay
ECM

Tech Tips

Bank 1 refers to the bank that includes the No. 1 cylinder.
Bank 2 refers to the bank that does not include the No. 1 cylinder.
Sensor 1 refers to the sensor closer to the engine assembly.
Sensor 2 refers to the sensor farther away from the engine assembly.

MONITOR DESCRIPTION

The sensing portion of the heated oxygen sensor has a zirconia element which is used to detect oxygen concentration in the exhaust. If the zirconia element is at the appropriate temperature and the difference of the oxygen concentrations between the inside and outside surface of the sensor is large, the zirconia element will generate voltage signals. In order to increase the oxygen concentration detecting capacity of the zirconia element, the ECM supplements the heat from the exhaust with the heat from the heating element inside the sensor. When the current in the sensor is out of the standard operating range, the ECM interprets this as a fault in the heated oxygen sensor heater and sets a DTC.
Example:
The ECM will set a high current DTC if the current in the sensor is more than 2 A when the heater is OFF. Similarly, the ECM will set a low current DTC if the current is less than 0.3 A when the heater is ON.

WIRING DIAGRAM

Refer to DTC P0136 Click here.

INSPECTION PROCEDURE

Tech Tips

Read freeze frame data using the intelligent tester. Freeze frame data records the engine conditions when a malfunction is detected. When troubleshooting, freeze frame data can help determine if the vehicle was running or stopped, 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.
Sensor 1 refers to the sensor mounted before the Three-Way Catalytic Converter (TWC) and is located near the engine assembly.
Sensor 2 refers to the sensor mounted after the TWC and is located far from the engine assembly.

PROCEDURE

INSPECT HEATED OXYGEN SENSOR (HEATER RESISTANCE)

Disconnect the H12 and H13 heated oxygen sensor connectors.

Measure the resistance of the sensor.

Standard resistance

Bank 1
Tester Connection	Condition	Specified Condition
1 (HT1B) - 2 (+B)	20°C (68°F)	11 to 16 Ω
1 (HT1B) - 4 (E2)	-	10 kΩ or higher

Bank 2
Tester Connection	Condition	Specified Condition
1 (HT2B) - 2 (+B)	20°C (68°F)	11 to 16 Ω
1 (HT2B) - 4 (E2)	-	10 kΩ or higher

REPLACE HEATED OXYGEN SENSOR

INSPECT INTEGRATION NO.1 RELAY (MAIN RELAY)

Disconnect the integration relay from the engine room junction block.

Measure the voltage of the MAIN relay.

Standard resistance

Tester Connection	Condition	Specified Condition
1J-5 - Body ground	Ignition switch ON	10 to 14 V

REPLACE INTEGRATION NO.1 RELAY

CHECK ECM (HT1B, HT2B VOLTAGE)

Turn the ignition switch ON.

Measure the voltage of the ECM connector.

Standard voltage

Tester Connection	Specified Condition
E15-1 (HT1B) - E17-1 (E1)	9 to 14 V
E16-5 (HT2B) - E17-1 (E1)	9 to 14 V

REPLACE ECM

CHECK WIRE HARNESS (HEATED OXYGEN SENSOR - ECM AND INTEGRATION RELAY (MAIN RELAY))

Disconnect the H12 or H13 sensor connectors.
Disconnect the E15 or E16 ECM connector.
Disconnect the 1J connector from the engine room junction block.

Measure the resistance of the wire harness side connectors.

Standard resistance

Bank 1 Sensor 2
Tester Connection	Specified Condition
H12-1 (HT1B) - E15-1 (HT1B)	Below 1 Ω
H12-2 (+B) - 1J-5	Below 1 Ω
H12-1 (HT1B) or E15-1 (HT1B) - Body ground	10 kΩ or higher
H12-2 (+B) or 1J-5 - Body ground	10 kΩ or higher

Bank 2 Sensor 2
Tester Connection	Specified Condition
H13-1 (HT2B) - E16-5 (HT2B)	Below 1 Ω
H13-2 (+B) - 1J-5	Below 1 Ω
H13-1 (HT2B) or E16-5 (HT2B) - Body ground	10 kΩ or higher
H13-2 (+B) or 1J-5 - Body ground	10 kΩ or higher

REPAIR OR REPLACE HARNESS AND CONNECTOR

REPLACE ECM