P0141

Diagnostic Chart:

Wiring Diagram:

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 SETTING THE DTC

^ 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).

^ Throttle Position (TP) is less than 18%.

^ HO2S 2 voltage increases less than 150 mV in 100 to 190 seconds.

ACTION TAKEN WHEN THE DTC SETS

^ The Malfunction Indicator Lamp (MIL) will illuminate after two consecutive ignition cycles in which the diagnostic runs with the malfunction present.

^ The PCM will record the operating conditions at the time that the diagnostic fails. This information will store in the Freeze Frame and Failure Records buffers.

^ A history DTC stores.

CONDITIONS FOR CLEARING THE MIL/DTC

^ The MIL will turn off after 3 consecutive ignition cycles in which the diagnostic runs without a fault.

^ A history DTC will clear after 40 consecutive warm up cycles without a fault.

^ A scan tool can clear the DTCs.

DIAGNOSTIC AIDS

A rubbed through wire insulation or a wire contacting the exhaust could cause an intermittent condition.

Check for a poor connection or a damaged harness. Inspect the harness connectors for the following conditions. Refer to Heated Oxygen Sensor (O2S) Service and Repair.

^ Improper mating.

^ Broken locks.

^ Improperly formed connectors.

^ Damaged terminals.

^ A poor terminal to wire connection.

^ A damaged harness.

TEST DESCRIPTION

Number(s) below refer to the step number(s) on the Diagnostic Table.

1. The Powertrain OBD System Check prompts the technician to complete some basic checks and store the freeze frame and failure records data on the scan tool if applicable. This creates an electronic copy of the data taken when the malfunction occurred. The information is then stored on the scan tool for later reference.

2. This step determines if DTC P0141 is the result of a hard malfunction or an intermittent condition. With the ignition switch ON, engine OFF, the HO2S 2 voltage displayed on the scan tool should change within several minutes towards 0 or 1.0 volt, indicating that the heater is working properly.

3. Probing terminal D of the HO2S 2 electrical connector verifies if voltage is available to the HO2S 2 heater.

4. If voltage is available at the electrical connector, then it becomes a good voltage source to check for a ground at terminal C.

5. Determines if voltage is not available at the HO2S 2 due to an open O2 fuse or open ignition feed circuit. If the fuse is open, determine if it was due to a short in the ignition feed circuit before replacing the fuse.