P0141

DTC P0141 HO2S Heater Performance Sensor 2




Circuit Description
The HO2S 2, located in the exhaust stream past the catalytic converter, produces an output signal relative to the oxygen storage capacity of the catalytic converter. The PCM can then determine the ability of the catalytic converter to convert the exhaust emissions effectively. The HO2S 2 signal will be far less active than the signal produced by the front Oxygen Sensor 1 (O2S 1).

Conditions for Running the DTC
- No active MAP DTC's
- No active IAT DTC's
- No active ECT DTC's
- No active TP DTC's
- No active Fuel Trim DTC's
- No active Injector Control DTC's
- No active Misfire DTC's
- No active CKP DTC's
- No active EVAP DTC's
- No active IAC DTC's
- Engine Coolant Temperature (ECT) less than 40° C (104° F).
- Intake Air Temperature (IAT) less than 40° C (104° F).
- Difference between ECT and IAT is less than 7° C (45° F).
- The battery voltage is between 11.6 Volts and 16 Volts.
- The engine has been running less than 400 seconds.

Conditions for Setting the DTC
HO2S 2 voltage increases less than 150 mV in 100 to 190 seconds.

Action Taken When the DTC Sets
- The control module illuminates the malfunction indicator lamp (MIL) if a failure is detected during 2 consecutive key cycles.
- The control module sets the DTC and records the operating conditions at the time the diagnostic failed. The failure information is stored in the scan tool's Freeze Frame and Failure Records.

Conditions for Clearing the MIL/DTC
- The control module turns OFF the MIL after 3 consecutive drive trips when the test has Run and Passed
- A history DTC will clear if no fault conditions have been detected for 40 warm-up cycles. A warm up cycle occurs when the coolant temperature has risen 22° C (40° F) from the startup coolant temperature and the engine coolant reaches a temperature that is more than 70° C (158° F) during the same ignition cycle.
- Use the scan tool Clear Information function

Diagnostic Aids
Replace the entire HO2S 2 assembly. Do not attempt to repair the HO2S 2 if the following conditions exist:
- Damaged wiring
- Damaged electrical connector
- Damaged terminals

Obstruction of the air reference and degrade HO2S 2 performance could result in any attempt to repair the above conditions.

The HO2S 2 must have a clean air reference in order for the HO2S 2 to function properly. This clean air reference is obtained by way of the HO2S 2 wires.

An intermittent may be caused by any of the following conditions:
- A poor connection
- Rubbed through wire insulation
- A broken wire inside the insulation

Thoroughly check any circuitry that is suspected of causing the intermittent complaint. Refer to Testing for Intermittent and Poor Connections.

If a repair is necessary, refer to Wiring Repairs or Connector Repairs.

Steps 4 - 5:

Steps 6 - 8:

Steps 9 - 13:

Steps 14 - 15:

Test Description
The numbers below refer to the step numbers on the Diagnostic Table.
2. As the heater warms the oxygen sensor to operating temperature, the HO2S will output a voltage in relation to the amount of oxygen in the exhaust. With the ignition ON and the engine OFF the exhaust usually contains a high oxygen content. With the engine OFF the HO2S voltage will usually decrease from the initial (bias) voltage due to the high oxygen content.
4. This step checks for proper HO2S heater ignition positive voltage and ground supply.
5. This step checks for proper PCM and signal circuit operation.