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 P0050: HO2S Heater Control Circuit Bank 2 Sensor 1DTC P0056: HO2S Heater Control Circuit Bank 2 Sensor 2
DTC P0059: HO2S Heater Resistance Bank 2 Sensor 1
DTC P0060: HO2S Heater Resistance Bank 2 Sensor 2
DTC P0155: HO2S Heater Performance Bank 2 Sensor 1
DTC P0161: HO2S Heater Performance Bank 2 Sensor 2
Diagnostic Fault Information
Circuit | Short to Ground | High Resistance | Open | Short to Voltage | Signal Performance |
|---|---|---|---|---|---|
HO2S Heater Voltage Supply | Opens fuse P0030, P0036, P0050, P0053, P0054, P0056, P0059, P0060, P0102, P0134, P0135, P0140, P0141, P0154, P0155, P0160, P0161, P0443, P0480, P0481, P0645 | P0050, P0059, P0155 | P0050, P0059, P0155 | P0690 | P0155 |
HO2S Heater Low Control | P0050, P0155 | P0050, P0059, P0155 | P0050, P0059, P0155 | P0050, P0155, P0690 | P0155 |
Circuit | Short to Ground | High Resistance | Open | Short to Voltage | Signal Performance |
|---|---|---|---|---|---|
HO2S Heater Voltage Supply | Opens fuse P0030, P0036, P0050, P0053, P0054, P0056, P0059, P0060, P0102, P0134, P0135, P0140, P0141, P0154, P0155, P0160, P0161, P0443, P0480, P0481, P0645 | P0056, P0060, P0161 | P0056, P0060, P0161 | P0056, P0161, P0690 | P0161 |
HO2S Heater Low Control | P0050, P0056 | P0056, P0060, P0160 | P0056, P0060, P0161 | P0056, P0161, P0690 | P0161 |
Typical Scan Tool Data
Circuit | Normal Range | Short to Ground | Open | Short to Voltage |
|---|---|---|---|---|
HO2S Heater Voltage Supply | Approximately 0.5-2 A | 0.00 A | 0.00 A | Approximately 0.5-2 A |
HO2S Heater Voltage Supply | 7-100% | 7% | 7% | 7-100% |
HO2S Heater Low Control | Approximately 0.5-2 A | 0.00 A | 0.00 A | 0.00 A |
HO2S Heater Low Control | 7-100% | 7% | 7% | 7% |
Circuit | Normal Range | Short to Ground | Open | Short to Voltage |
|---|---|---|---|---|
HO2S Heater Voltage Supply | Approximately 0.5-2 A | 0.00 A | 0.00 A | Approximately 0.5-2 A |
HO2S Heater Voltage Supply | 7-100% | 7% | 7% | 7-100% |
HO2S Heater Low Control | Approximately 0.5-2 A | 0.00 A | 0.00 A | 0.00 A |
HO2S Heater Low Control | 7-100% | 7% | 7% | 7% |
Circuit/System Description
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 an ignition voltage circuit through a fuse. With the engine running, ground is provided to the heater by the HO2S heater low control circuit, through a low side driver within the engine control module (ECM). The ECM uses pulse width modulation (PWM) to control the HO2S heater operation to maintain a specific HO2S operating temperature range.
Conditions for Running the DTC
P0050 and P0056
| • | The engine is cranking or running. |
| • | The Engine Speed parameter is greater than 400 RPM. |
| • | The system voltage is between 10-18 volts. |
P0059 and P0060
| • | DTCs P0112, P0113, P0116, P0117, P0118, P0128, P1258, P2610 are not set. |
| • | The ignition is OFF for more than 8 hours. |
| • | The difference between the start-up engine coolant temperature (ECT) and the intake air temperature (IAT) is less than 8°C (14.4°F). |
| • | The ECT Sensor parameter is between -30 and +45°C (-22 and +133°F) at engine start-up. |
| • | The system voltage is between 10-18 volts. |
| • | This diagnostic runs one time per valid cold start when the above conditions are met. |
P0155
| • | DTCs P0050, P0059, P0068, P0101, P0102, P0103, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120, P0121, P0122, P0123, P0128, P0201, P0202, P0203, P0204, P0205, P0206, P0220, P0222, P0223, P0442, P0443, P0446, P0449, P0451, P0452, P0453, P0454, P0455, P0496, P1516, P2101, P2119, P2135, P2176 are not set. |
| • | The system voltage is between 10-18 volts. |
| • | The scan tool special functions are not active. |
| • | The Engine Run Time parameter is more than 180 seconds. |
| • | The ECT Sensor parameter is at least 65°C (149°F). |
| • | The Engine Speed parameter is between 500-3,000 RPM. |
| • | The MAF sensor parameter is between 5-30 g/s. |
| • | The above conditions have been met for more than 2 seconds. |
P0161
| • | DTCs P0056, P0060, P0068, P0101, P0102, P0103, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120, P0121, P0122, P0123, P0128, P0201, P0202, P0203, P0204, P0205, P0206, P0220, P0222, P0223, P0442, P0443, P0446, P0449, P0451, P0452, P0453, P0454, P0455, P0496, P1516, P2101, P2119, P2135, P2176 are not set. |
| • | The system voltage is between 10-18 volts. |
| • | The scan tool special functions are not active. |
| • | The Engine Run Time parameter is at least 180 seconds. |
| • | The ECT parameter is at least 65°C (149°F). |
| • | The Engine Speed parameter is between 500-3,000 RPM. |
| • | The MAF Sensor parameter is between 5-30 g/s. |
| • | The above conditions have been met for more than 2 seconds. |
Conditions for Setting the DTC
P0050 and P0056
| • | The ECM detects that the HO2S heater control circuit status is incorrect for more than 2 seconds. |
| • | This diagnostic runs continuously. |
P0059
The ECM detects that the HO2S heater calculated resistance is not between 1.3-7.5 ohms at engine start-up for 1 second.
P0060
The ECM detects that the HO2S heater calculated resistance is not between 1.9-8.6 ohms at engine start-up for 1 second.
P0155
| • | The HO2S heater current is less than 0.25 amp or more than 3.13 amps for more than 8 seconds, twice in a 1-minute period. |
| • | The test is run 2 times per trip. |
P0161
| • | The HO2S heater current is less than 0.43 amp or more than 2.90 amp for more than 8 seconds, twice within a 1-minute test period. |
| • | The test is run 2 times per trip. |
Action Taken When the DTC Sets
DTCs P0050, P0056, P0059, P0060, P0155, and P0161 are Type B DTCs.
Conditions for Clearing the MIL/DTC
DTCs P0050, P0056, P0059, P0060, P0155, and P0161 are Type B DTCs.
Diagnostic Aids
When using a high impedance, low current draw, test lamp to load the heater circuit, the test lamp flash may be dim, the scan tool Heater Command parameter may indicate 7 percent, and the Heater parameter may indicate 0.00 amps. This is a normal condition.
Reference Information
Schematic Reference
Connector End View Reference
Electrical Information Reference
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
- Allow the engine to reach operating temperature.
- Engine running, verify the appropriate scan tool HO2S Heater parameter is varying between 0.5-2 amp.
- Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.
Circuit/System Testing
Important: You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.
- Ignition OFF, disconnect the harness connector at the appropriate HO2S.
- Ignition ON, verify that a test lamp illuminates between the appropriate HO2S heater voltage supply circuit terminal D and ground.
- Ignition ON, verify that a test lamp does not illuminate between the appropriate HO2S heater voltage supply circuit terminal D and the appropriate HO2S heater low control circuit terminal listed below:
- Engine running, leave the test lamp connected from the previous step. The lamp should flash or be ON steady.
- Ignition OFF, install a 30A fused jumper wire between the appropriate HO2S heater voltage supply circuit terminal D and the appropriate HO2S heater low control circuit terminal listed below:
- Engine running, verify the appropriate scan tool HO2S Heater parameter is less than 0.1 amp.
- If the ECM and all circuits test normal, replace the appropriate HO2S.
| ⇒ | If the test lamp does not illuminate, test the HO2S heater voltage supply circuit for a short to ground or an open/high resistance. If the circuit tests normal and the HO2S heater voltage supply circuit fuse is open, test all components connected to the fuse and replace as necessary. |
| • | B2S1 terminal C |
| • | B2S2 terminal E |
| ⇒ | If the lamp illuminates, test the HO2S heater low control circuit for a short to ground. If the circuit tests normal, replace the ECM. |
| ⇒ | If the test lamp is not ON steady or flashing, test the HO2S heater low control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM. |
Important:
• The output driver should detect a short to voltage and turn OFF. If a resistance fault is present the driver will remain ON and the scan tool will display more than 0.0 amp. Less than 10 ohms of resistance may set a DTC. • Performing this test may set additional DTCs.
| • | B2S1 terminal C |
| • | B2S2 terminal E |
| ⇒ | If more than the specified range, test the HO2S heater voltage supply and HO2S heater low control circuits for more than 1 ohm of resistance. If the circuits test normal, replace the ECM. |
Repair Instructions
Notice: Refer to Heated Oxygen Sensor Resistance Learn Reset Notice in the Preface section.
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for ECM replacement, setup, and programming |
