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 P0031 : HO2S Heater Control Circuit Low Voltage Sensor 1
DTC P0032 : HO2S Heater Control Circuit High Voltage Sensor 1
DTC P0053 : HO2S Heater Resistance Sensor 1
DTC P0135 : HO2S Heater Performance Sensor 1

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage
--- | --- | --- | ---
Heater Voltage Supply | P0031, P0130 | P0030, P0053, P0130, P0135 | --
Heater Low Control | P0030, P0130 | P0031, P0053, P0135 | P0032
Reference Voltage (Signal) | P0131 | P0130, P2243 | P0132
Low Reference (Ground) | P0130, P0136 | P0130, P2251 | P0132
Pump Current | P0130, P0131, P2237 | P2237 | P0132, P2237
Trim Current | P0130, P0131, P2626 | P2626 | P0132, P2626

### Circuit/System Description

Heating elements inside the heated oxygen sensor (HO2S) minimize the time required for the sensors to reach operating temperature and provide an accurate voltage signal. A low side driver within the engine control module (ECM) is pulse-width controlled to provide current to the heater elements. The ECM will not allow continuous HO2S heating until calibrated limits of time, temperature, and intake airflow have been reached. The ECM continuously monitors the HO2S heater current draw and operating state by briefly turning OFF the heater low side driver at regular intervals. A small reference voltage of approximately 4.9 volts is present at the heater low control circuit. When the low side driver is commanded ON the reference voltage is low. When the low side driver is commanded OFF the reference voltage is high, close to battery voltage. If the ECM detects that the predicted voltage and the detected voltage are different, a DTC sets.

### Conditions for Running the DTC

#### P0030, P0031, P0032

• | The engine is running

• | The Ignition 1 Signal parameter is more than 10 volts.

#### P0053

• | DTCs P0030, P0031, P0032, P0121, P0122, P0123, P0130, P0131, P0132, P0335, P0338, P2237, P2243, P2251, P2626 are not set.

• | The engine is started.

• | DTC P0053 runs once per drive cycle when the above conditions are met.

#### P0135

• | DTCs P0030, P0031, P0032, P0131, P0132, P0335, P0336, P0338, P2237, P2243, P2251, P2626 are not set.

• | The engine is running.

• | The ignition 1 signal parameter is more than 10 volts and less than 18.1 volts.

### Conditions for Setting the DTC

#### P0030, P0031, P0032

The ECM detects that the difference between the predicted voltage and the actual voltage exceeds a calibrated limit.

#### P0053

The ECM detects that the difference between the predicted resistance and the actual resistance of the HO2S 1 heater exceeds a calibrated limit.

#### P0135

• | The ECM detects that the sensor temperature remains below a threshold after a specified time after engine start.

• | The condition exists for more than 4 seconds.

| OR

• | The ECM detects that the calculated HO2S temperature is less than a predetermined threshold with 100 percent heater duty cycle.

• | The condition exists for more than 4 seconds.

### Action Taken When the DTC Sets

DTC P0030, P0031, P0053, P0135 are Type B DTCs.

### Conditions for Clearing the DTC

DTC P0030, P0031, P0053, P0135 are Type B DTCs.

### Reference Information

#### Schematic Reference

Engine Controls Schematics

#### Connector End View Reference

• | Engine Control Module Connector End Views

• | Engine Controls Connector End Views

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

• | Heated Oxygen Sensor Wiring Repairs

#### DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

#### Scan Tool Reference

• | Scan Tool Data List

• | Scan Tool Data Definitions

• | Scan Tool Output Controls

### Circuit/System Verification

1. Clear the DTCs with a scan tool.
2. Operate the vehicle within the conditions for running and setting the DTC. The DTC should not set.

### Circuit/System Testing

You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.

1. Ignition OFF, disconnect the harness connector at the HO2S 1.
2. Ignition ON, verify that a test lamp illuminates between the HO2S 1 heater voltage supply circuit terminal 4 and ground.

⇒ | If the test lamp does not illuminate, test the HO2S 1 heater voltage supply circuit for a short to ground or an open/high resistance. If the circuit tests normal and the HO2S 1 heater voltage supply circuit fuse is open, test all components connected to the fuse and replace as necessary.

3. Ignition ON, measure for approximately 4.9 volts between the HO2S 1 heater low control circuit terminal 3 and ground.

⇒ | If less than the specified value, test the HO2S 1 heater low control circuit for an open/high resistance or a short to ground. If the circuit tests normal, replace the ECM.

⇒ | If more than the specified value, test the HO2S 1 heater low control circuit for a short to voltage. If the circuit tests normal, replace the ECM.

4. Engine OFF, install a test lamp between the HO2S 1 voltage supply circuit terminal 4 and the HO2S 1 heater low control circuit terminal 3. Allow the ECM to power down.
5. Engine RUNNING, the lamp should be ON steady.

⇒ | If the test lamp is not on steady, replace the ECM.

6. If the ECM and all circuits test normal, replace the HO2S 1.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Heated Oxygen Sensor 1 Replacement

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