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 provide an overview of each diagnostic category. |
DTC Descriptors
DTC P0030: HO2S Heater Control Circuit Bank 1 Sensor 1DTC P0031: HO2S Heater Control Circuit Low Voltage Bank 1 Sensor 1
DTC P0032: HO2S Heater Control Circuit High Voltage Bank 1 Sensor 1
DTC P0036: HO2S Heater Control Circuit Bank 1 Sensor 2
DTC P0037: HO2S Heater Control Circuit Low Voltage Bank 1 Sensor 2
DTC P0038: HO2S Heater Control Circuit High Voltage Bank 1 Sensor 2
DTC P0050: HO2S Heater Control Circuit Bank 2 Sensor 1
DTC P0051: HO2S Heater Control Circuit Low Voltage Bank 2 Sensor 1
DTC P0052: HO2S Heater Control Circuit High Voltage Bank 2 Sensor 1
DTC P0056: HO2S Heater Control Circuit Bank 2 Sensor 2
DTC P0057: HO2S Heater Control Circuit Low Voltage Bank 2 Sensor 2
DTC P0058: HO2S Heater Control Circuit High Voltage Bank 2 Sensor 2
Diagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Ignition 1 Voltage | P0030, P0031, P0036, P0037, P0050, P0051, P0057 | P0030, P0031, P0036, P0037, P0050, P0051, P0057 | -- | -- |
HO2S Heater Control Circuit Bank 1 Sensor 1 | P0031 | P0030 | P0032 | -- |
HO2S Heater Control Circuit Bank 1 Sensor 2 | P0037 | P0036 | P0038 | -- |
HO2S Heater Control Circuit Bank 2 Sensor 1 | P0051 | P0050 | P0052 | -- |
HO2S Heater Control Circuit Bank 2 Sensor 2 | P0057 | P0056 | P0058 | -- |
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 1 voltage circuit through a fuse. Ground is provided to the heater on the low control circuit by a low side driver within the control module. The control module monitors the current draw of the heater to determine if a failure is present.
The HO2S utilizes the following circuits:
| • | A signal circuit |
| • | A low reference circuit |
| • | An ignition 1 voltage circuit |
| • | A heater control circuit |
Conditions for Running the DTC
| • | The ignition is ON, or the engine is running. |
| • | The ignition 1 voltage is greater than 10 volts. |
| • | The DTCs run continuously once the above conditions are met. |
Conditions for Setting the DTC
P0031, P0032, P0037, P0038, P0051, P0052, P0057, or P0058
| • | The engine control module (ECM) detects a short to ground or a short to voltage on the heater control circuit of the HO2S. |
| • | The condition exists for more than 2 seconds |
P0030, P0036. P0050 or P0056
| • | The ECM detects an open on the heater control circuit of the HO2S. |
| • | The condition exists for more than 2 seconds |
Action Taken When the DTC Sets
DTCs P0030, P0031, P0032, P0036, P0037, P0038, P0050, P0051, P0056, P0057, and P0058 are Type A DTCs.
Conditions for Clearing the MIL/DTC
DTCs P0030, P0031, P0032, P0036, P0037, P0038, P0050, P0051, P0056, P0057, and P0058 are Type A DTCs.
Reference Information
Schematic Reference
Connector End View Reference
Electrical Information Reference
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Circuit/System Verification
- With the engine at normal operating temperature, operate the engine above 1,200 RPM for 30 seconds and then allow the engine to idle. DTCs P0030, P0031, P0032, P0036, P0037, P0038, P0050, P0051, P0056, P0057, and P0058 should not set.
- If the vehicle passes the Circuit/System Verification test, then operate the vehicle within the conditions for running the DTC. You may also operate the vehicle within the conditions that are captured in the Freeze Frame/Failure Records Data List.
Important: It may take up to 8 minutes for the DTC to set.
Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the appropriate HO2S.
- Ignition ON, verify that a test lamp illuminates between the ignition 1 voltage circuit and ground.
- Ignition OFF, connect a test lamp between the control circuit and B+. Verify the test lamp does not illuminate.
- Engine idling, verify the test lamp illuminates or flashes.
- If all circuits test normal, test or replace the HO2S sensor.
Important: The ignition 1 voltage circuit supplies voltage to other components. Make sure you test all circuits for a short to ground or test all components for being shorted that share the ignition 1 voltage circuit.
| ⇒ | If the test lamp does not illuminate, test the ignition 1 voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal and the ignition 1 voltage circuit fuse is open, test all components connected to the ignition 1 voltage circuit and replace as necessary. |
| ⇒ | If test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the ECM. |
Important: The control circuit of the HO2S heater is pulled up to voltage within the ECM, 3.5-4.5 volts on the control circuit is normal.
| ⇒ | If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM. |
Component Testing
- Ignition OFF, disconnect the harness connector of the appropriate HO2S.
- Test for 4-5 ohms of resistance for the HO2S 1 heater element, or 11-12 ohms of resistance for the HO2S 2 heater element.
| ⇒ | If not within the specified range, replace the HO2S sensor. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for engine control module replacement, setup, and programming |
