P0161
DTC P0135, P0141, P0155, or P0161
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) provides an overview of each diagnostic category.
DTC Descriptors
DTC P0135
- HO2S Heater Performance Bank 1 Sensor 1
DTC P0141
- HO2S Heater Performance Bank 1 Sensor 2
DTC P0155
- HO2S Heater Performance Bank 2 Sensor 1
DTC P0161
- HO2S Heater Performance Bank 2 Sensor 2
Diagnostic Fault Information
Circuit Description
The heated oxygen sensor (HO2S) heater reduces the time required for the oxygen sensor to reach operating temperature and maintains the operating temperature during extended idle periods. When the ignition is turned to the ON position, ignition voltage is supplied directly to the sensor heater. The engine control module (ECM) controls the heater operation by first modulating the control circuit to ground when the sensors are cold. This prevents the possibility of thermal shock to the sensor, from condensation build-up on the sensor, by controlling the sensor's rate of heating. After a predetermined amount of time, the ECM commands the heaters ON continuously. Once the sensor reaches operating temperature, the ECM may modulate the heater control circuit to ground to maintain a desired temperature. The ECM controls the heater by grounding the control circuit with a solid state device called a driver. The driver is equipped with a feedback circuit that is pulled up to voltage. The ECM can determine if the control circuit is open, shorted to ground, or shorted to a voltage by monitoring the feedback voltage.
Conditions for Running the DTC
P0135 or P0155
* Before the ECM can report DTC P0135 or P0155 failed, P0030, P0031, P0032, P0050, P0051, P0052, P0130, P0131, P0132, P0134, P0150, P0151, P0152, P0154, must run and pass.
* The engine has cycled ON and OFF greater than 6 to 16 times dependent on coolant temperature.
* The engine speed is greater than 25 RPM.
* The startup engine coolant temperature (ECT) is warmer than -10°C (14°F).
* The calculated catalyst temperature is within 5-480°C (41-896°F) dependent on coolant temperature.
* The HO2S 1 heater is commanded ON at 100 percent.
* The ignition voltage is between 11-16 volts.
* The calculated exhaust temperature is warmer than 350°C (662°F).
* The engine is not in decel fuel cut-off (DFCO).
* The engine has operated for greater than 90 seconds at least once between auto-stops during the ignition cycle.
* DTC P0135 and P0155 run continuously and once per engine start when the conditions above are met.
P0141 or P0161
* Before the ECM can report DTC P0141 or P0161 failed, DTCs P0036, P0037, P0038, P0056, P0057, P0058, P0137, P0138, P0140, P0157, P0158, P0160, P2232, and P2235 must run and pass.
* The engine is operating.
* The ignition voltage is between 11-18 volts.
* The engine has cycled ON and OFF greater than 6, to 16 times, dependent on coolant temperature.
* The intake air temperature (IAT) is warmer than -30°C (-22°F).
* The engine is not in decel fuel cut-off (DFCO).
* The calculated exhaust temperature at the HO2S 2 is colder than 451°C (844°F).
OR
* The calculated internal resistance of the HO2S 2 is less than 40,000 ohms.
* The calculated exhaust temperature at the HO2S 2 is warmer than 699°C (1,290°F).
OR
* The HO2S 2 is at operating temperature.
* The calculated exhaust temperature is 300-700°C (572-1,292°F).
* The HO2S 2 is commanded ON at greater than 49 percent.
* The difference in HO2S 2 signal voltage is greater 0 mV during an HO2S 2 heater ON to OFF, or OFF to ON cycle.
* DTCs P0141 and P0161 run continuously once the above conditions are met for approximately 8 seconds.
Conditions for Setting the DTC
P0135 and P0155
* The ECM detects that the HO2S 1 heater element temperature is colder than a threshold for greater than 60 seconds after an auto-start.
OR
* The ECM detects that the HO2S 1 heater element temperature is colder than a predetermined value for greater 40 seconds.
P0141 and P0161
The ECM detects that the HO2S 2 internal resistance is greater than 650 to 1,000 ohms during a sample period of 10 HO2S 2 heater ON/OFF and OFF/ON cycles. The condition exists for greater than 10 seconds.
Action Taken When the DTC Sets
DTCs P0135, P0141, P0155, and P0161 are Type B DTCs.
Conditions for Clearing the MIL/DTC
DTCs P0135, P0141, P0155, and P0161 are Type B DTCs.
Reference Information
Schematic Reference
Engine Controls Schematics (Electrical Diagrams)
Connector End View Reference
Component Connector End Views (Connector Views)
Electrical Information Reference
* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions (Diagnostic Trouble Code Descriptions)
Scan Tool Reference
Control Module References (Programming and Relearning) for scan tool information
Circuit/System Verification
Note: It may take up to 8 minutes for the DTC to set.
1. With the engine at normal operating temperature, operate the engine above 1,200 RPM for 2 minutes and then allow the engine to idle. DTCs P0135, P0141, P0155, or P0161 should not set.
2. 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, open the hood to disable the Auto-Stop function.
2. Ignition ON, verify the scan tool hood position parameter displays Open.
• If the hood position does not display Open, refer to DTC P254F (P254F).
3. Ignition OFF, disconnect the harness connector at the appropriate HO2S.
4. Ignition ON, test for B+ between the ignition voltage circuit terminal listed below and ground:
* Bank 1 or Bank 2 Sensor 1 terminal 4
* Bank 1 or Bank 2 Sensor 2 terminal D
• If less than the specified range, repair the ignition voltage circuit for a short to ground or an open/high resistance.
5. Ignition ON, test for 2-3 V between the appropriate control circuit terminal listed below and ground:
* Bank 1 or Bank 2 Sensor 1 terminal 3
* Bank 1 or Bank 2 Sensor 2 terminal E
• If less than the specified range, test the control circuit for a short to ground or an open/high resistance. If the circuit/connections test 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.
6. Connect a test lamp between the appropriate heater control circuit terminal listed below and B+.
* Bank 1 or Bank 2 Sensor 1 terminal 3
* Bank 1 or Bank 2 Sensor 2 terminal E
7. Engine idling for 2 minutes, verify the test lamp illuminates or flashes.
• If the test lamp is always OFF, test the control circuit for a high resistance. If the circuit/connections test normal, replace the ECM.
8. If all circuits/connections test normal, test or replace the HO2S.
Component Testing
1. Ignition OFF, disconnect the harness connector at the appropriate HO2S.
2. Test for 3-8 ohm between the ignition voltage terminal and the heater control terminal.
• If not within the specified range, replace the HO2S.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Heated Oxygen Sensor Replacement - Bank 1 Sensor 1 (Service and Repair)
* Heated Oxygen Sensor Replacement - Bank 1 Sensor 2 (Service and Repair)
* Heated Oxygen Sensor Replacement - Bank 2 Sensor 1 (Service and Repair)
* Heated Oxygen Sensor Replacement - Bank 2 Sensor 2 (Service and Repair)
* Control Module References (Programming and Relearning) for engine control module replacement, setup, and programming