Troubleshooting

DTC P0037 OXYGEN SENSOR HEATER CONTROL CIRCUIT LOW (BANK 1 SENSOR 2)

CIRCUIT DESCRIPTION

DTC Detection Condition:

The heated oxygen sensor's output voltage changes sharply when the air-fuel ratio is near the ideal stoichio-metric air-fuel ratio. This sensor reaction is useful for detecting the oxygen concentration in the exhaust gas and for providing the ECM with data about what adjustments are necessary for the air-fuel ratio.

If the oxygen concentration in the exhaust gas increases and the heated oxygen sensor voltage is below 0.45 V, the air-fuel ratio is "LEAN". The heated oxygen sensor informs the ECM about the LEAN condition. If the oxygen concentration in the exhaust gas increases and the heated oxygen sensor voltage is about 0.45 V, the air-fuel ratio is "RICH". The heated oxygen sensor informs the ECM about the RICH condition.






HINT: The ECM provides 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.

HINT:
- Bank 1 refers to the bank that includes cylinder No. 1.
- Bank 2 refers to the bank that excludes cylinder No. 1.
- Sensor 1 refers to the sensor closer to the engine body.

MONITOR DESCRIPTION

Monitor Strategy:

Typical Enabling Conditions:

Typical Malfunction Thresholds:

Component Operating Range:

Monitor Result (Mode 06 Data):

The sending 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 proper temperature, and the difference of the oxygen concentration 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 in the zirconia element, the ECM supplements the heat from the exhaust with heat from a heating element inside the sensor. When current in the sensor is out of the standard operating range, the ECM interprets this as a fault in the heated oxygen sensor 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 0.25 A when the heater is ON.

Wiring Diagram:

Step 1 - 2:

Step 3 - 4:

INSPECTION PROCEDURE

HINT: Read freeze frame data using the hand-held tester or the OBD II scan tool. 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, as well as other data from the time when a malfunction occurred.