NGC

P0037-O2 SENSOR 1/2 HEATER CIRCUIT LOW





For a complete wiring diagram Consult Diagrams/Electrical.

- When Monitored:
Continuously during O2 heater operation with battery voltage between 10.4 and 15.75 volts.

- Set Condition:
The PCM detects that the O2 sensor heater element input is below the minimum acceptable voltage. One trip fault. Three good trips to turn off the MIL.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.Initial Inspection and Diagnostic Overview

Diagnostic Test

1. DTC IS ACTIVE
Start the engine and allow it to idle for at least 60 seconds.

WARNING: When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts, or fan. Do not wear loose clothing. Failure to follow these instructions can result in personal injury or death.

With a scan tool, select View DTCs.
Is the DTC Active at this time?

Yes

- Go to 2

No

- Refer to the *CHECKING FOR AN INTERMITTENT DTC Diagnostic Procedure.Checking For An Intermittent DTC

2. 1/2 OXYGEN SENSOR




Turn the ignition off.

NOTE: Allow the sensor to cool to ambient temperature before continuing. The voltage should stabilize between 4.6 and 5.0 volts.

Disconnect the 1/2 Oxygen Sensor harness connector.
Measure the resistance of the O2 sensor heater element across the 1/2 Oxygen Sensor connector between the heater control terminal and the ground terminal.

NOTE: The resistance of the heater element will vary according to temperature and should be measured at 21.1° C (70° F).

Is the resistance between 2.0 and 30.0 ohms?

Yes

- Go to 3

No

- Replace the 1/2 Oxygen Sensor.
- Perform the PCM Verification Test.Powertrain Verification Test

3. (K299) O2 1/2 HEATER CONTROL CIRCUIT SHORTED TO GROUND




Turn the ignition off.
Disconnect the Powertrain Control Module (PCM) connector.
Measure the resistance between ground and the (K299) O2 1/2 Heater Control circuit in the 1/2 Oxygen Sensor harness connector.
Is the resistance below 100 ohms?

Yes

- Repair the short to ground in the (K299) O2 1/2 Heater Control circuit.
- Perform the PCM Verification Test.Powertrain Verification Test

No

- Go to 4

4. EXCESSIVE RESISTANCE IN THE (K299) O2 1/2 HEATER CONTROL CIRCUIT




Turn the ignition off.

CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals, resulting in poor terminal to pin connection. Install Miller Special Tool #8815 to perform diagnosis.

Measure the resistance of the (K299) O2 1/2 Heater Control circuit between the 1/2 Oxygen Sensor harness connector and the appropriate terminal of special tool #8815.
Is the resistance below 0.5 ohms?

Yes

- Go to 5

No

- Repair the excessive resistance in the (K299) O2 1/2 Heater Control circuit.
- Perform the PCM Verification Test.Powertrain Verification Test

5. POWERTRAIN CONTROL MODULE (PCM)
Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the 1/2 Oxygen Sensor and the Powertrain Control Module (PCM).
Look for any chafed, pierced, pinched, or partially broken wires.
Look for broken, bent, pushed out or corroded terminals.
Verify that there is good pin to terminal contact in the 1/2 O2 Sensor and Powertrain Control Module connectors.
Search for any Technical Service Bulletins that may apply.
Were any problems found?

Yes

- Repair as necessary.
- Perform the PCM Verification Test.Powertrain Verification Test

No

- Replace and program the Powertrain Control Module (PCM).
- Perform the PCM Verification Test.Powertrain Verification Test