For 1990-2009 cars

### Diagnostic Instructions

• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

• | Review Strategy Based Diagnosis for an overview of the diagnostic approach.

• | Diagnostic Procedure Instructions provides an overview of each diagnostic category.

### DTC Descriptors

DTC P0030: HO2S Heater Control Circuit Sensor 1
DTC P0036: HO2S Heater Control Circuit Sensor 2
DTC P0053: HO2S Heater Resistance Circuit Sensor 1
DTC P0054: HO2S Heater Resistance Circuit Sensor 2
DTC P0135: HO2S Heater Performance Sensor 1
DTC P0141: HO2S Heater Performance Sensor 2

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Ignition Voltage | P0030, P0036, P0102, P0135, P0141, P0443, P0597, P0598 | P0030, P0036 | -- | --
HO2S 1 Heater Control | P0030, P0135 | P0030, P0132, P0135, P0137 | P0030, P0135, P0137 | P0135
HO2S 2 Heater Control | P0036, P0141 | P0036, P0138, P0140, P0141 | P0036, P0141 | P0141

### Circuit Description

The heated oxygen sensors (HO2S) are used for fuel control and post catalyst monitoring. Each HO2S compares the oxygen content of the surrounding air with the oxygen content in the exhaust stream. The HO2S must reach operating temperature to provide an accurate voltage signal. A heating element inside the HO2S minimizes the time required for the sensor to reach operating temperature. Voltage is provided to the heater by the ignition voltage circuit through a fuse. Ground is provided to the heater on the control circuit by a low side driver within the control module.

### Conditions for Running the DTC

#### P0030 and P0036

• | The engine is running.

• | The ignition voltage is between 11-18 volts.

• | The engine speed is greater than 400 RPM.

• | The DTCs run continuously when the above conditions are met.

#### P0053 and P0054

• | DTCs P0030, P0036, P0112, P0113, P0116, P0117, P0118, or P2610 are not set.

• | The ignition is OFF for greater than 8 hours.

• | The engine coolant temperature (ECT) and the intake air temperature (IAT) are within 8°C (14°F).

• | The ECT is between -30°C to +45°C (-22 to +113°F).

• | The ignition voltage is less than 18 volts.

• | The engine run time is greater than 200 milliseconds.

• | The DTCs run once per cold start-up when the above conditions are met.

#### P0135 and P0141

• | DTCs P0117 or P0118 are not set.

• | The ignition voltage is between 10-18 volts.

• | The HO2S heaters are at operating temperature.

• | The scan tool HO2S Heater device control is not active.

• | The commanded HO2S heater duty cycle is greater than 0 percent.

• | The DTCs run twice per ignition cycle when the above conditions are met for 120 seconds.

### Conditions for Setting the DTC

#### P0030 and P0036

The ECM detects that the commanded state of the driver and the actual state of the control circuit do not match for greater than 5 seconds.

#### P0053 and P0054

The ECM detects the HO2S heater is not within a specified resistance range at engine start-up.

#### P0135 and P0141

The ECM detects the HO2S heater current is less than 0.30 amps or greater than 2.5 amps for greater than 8 seconds.

### Action Taken When the DTC Sets

DTC P0030, P0036, P0053, P0054, P0135, and P0141 are Type B DTCs.

### Conditions for Clearing the MIL/DTC

DTC P0030, P0036, P0053, P0054, P0135, and P0141 are Type B DTCs.

### Diagnostic Aids

#### HO2S Terminal Identification

Lock Tab
1 | 2
3 | 4

• | If the condition is intermittent, move the related harnesses and connectors, with the engine operating, while monitoring the scan tool circuit status parameters for the component. The circuit status parameters change from OK or Not Run to Fault if there is a condition with the circuit or a connection.

• | An open fuse in the HO2S heater circuit may be caused by the heater element in one of the sensors. The condition may not be present until the sensor operates for a period of time. If no fault is present in the heater circuit, monitor the amperage of each heater with a scan tool to determine if one of the heater elements is the cause of the open fuse. Inspect the sensor pigtail or the harness for contacting the exhaust system.

### Reference Information

#### Schematic Reference

Engine Controls Schematics

#### Connector End View Reference

Component Connector End Views

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

#### Scan Tool Reference

Control Module References for scan tool information

### Circuit/System Verification

1. Engine idling, command the appropriate HO2S heater ON and OFF with a scan tool while observing the following control circuit status parameters:

• | Htr Ckt Short Gnd Test Status

• | Htr Ckt Open Test Status

• | Htr Ckt Short Volts Test Status

| Each parameter should display OK or Not Run.

2. Observe the HO2S Heater Command parameter with a scan tool. The reading should display greater than 0 percent.
3. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

### Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the appropriate HO2S.
2. Ignition ON, test for B+ between the ignition voltage circuit terminal 2 and ground.

⇒ | If less than the specified range, test the ignition voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal and the ignition voltage circuit fuse is open, test all components connected to the ignition voltage circuit and replace as necessary.

3. Ignition ON, test for 3-4 V between the control circuit terminal 4 and ground.

⇒ | If less than the specified range, test the control circuit for a short to ground, or an open/high resistance. If the circuit tests normal, replace the ECM.

⇒ | If greater than the specified range, test the control circuit for a short to voltage. If the circuit/connections test normal, replace the ECM.

4. Engine idling, command the HO2S to 100 percent with a scan tool. The DMM should transition from 3-4 V when commanded OFF to less than 1 V when commanded to 100%.

⇒ | If the circuit voltage does not correspond to the specified values, replace the ECM.

5. Ignition OFF, connect a 10 A fused jumper wire between the control circuit terminal 4 and the ignition circuit terminal 2.
6. Engine idling, observe the appropriate HO2S Heater Amps parameter. The reading should display 0.00 amps.

⇒ | If not the specified value, test the control circuit and the ignition voltage circuit for high resistance.

7. If all circuits test normal, test or replace the appropriate HO2S.

### Component Testing

1. Ignition OFF, disconnect the harness connector at the HO2S.
2. Test for 8-20 Ω between the ignition voltage circuit terminal 2 and the control circuit terminal 4.

⇒ | If not within the specified range, replace the HO2S sensor.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Caution: When replacing the HO2S perform the following:

• | A code clear with a scan tool, regardless of whether or not a DTC is set

• | HO2S heater resistance learn reset with a scan tool, where available

Perform the above in order to reset the HO2S resistance learned value and avoid possible HO2S failure.

• | Heated Oxygen Sensor Replacement - Sensor 1

• | Heated Oxygen Sensor Replacement - Sensor 2

• | Control Module References for ECM replacement, setup, and programming