P0141

Diagnostic Chart:

Wiring Diagram:

CIRCUIT DESCRIPTION

In order to control emissions, a catalytic converter is used to convert harmful exhaust emissions into harmless water vapor and carbon dioxide.

The PCM has the capability to monitor this process by using a Rear Heated Oxygen Sensor (HO2S 2). The HO2S 2, located in the exhaust stream past the catalytic converter, produces an output signal which indicates the storage capacity of the catalyst; this in turn indicates the catalyst's ability to convert exhaust emissions effectively. If the catalyst is functioning properly, the HO2S 2 signal will be far less active than the signal produced by the front Oxygen Sensor (O2S 1).

If the oxygen sensor pigtail wiring, connector or terminal are damaged, the entire oxygen sensor assembly must be replaced. DO NOT attempt to repair the wiring, connector or terminals. In order for the sensor to function properly, it must have a clean air reference provided to it. This clean air reference is obtained by way of the oxygen sensor wire(s). Any attempt to repair the wires, connectors or terminals could result in the obstruction of the air reference and degrade oxygen sensor performance.

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 fault active.

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

^ A history DTC is stored.

^ Coolant fan turns ON.

CONDITIONS FOR CLEARING THE MIL/DTC

^ The MIL will turn OFF after three 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.

^ DTC(s) can be cleared by using the scan tool.

DIAGNOSTIC AIDS

An intermittent may be caused by rubbed through wire insulation or a wire contacting the exhaust.

Check for poor connection or damaged harness - Inspect harness connectors for the following conditions:

^ Improper mating

^ Broken locks

^ Improperly formed

^ Damaged terminals

^ Poor terminal to wire connection

^ Damaged harness

TEST DESCRIPTION

An example test description follows:

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 fault 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 failure or an intermittent condition. With the ignition ON, engine OFF, the HO2S 2 voltage displayed on the scan tool should change within several minutes towards 0 or 1 volt, indicating that the heater is working properly.

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

4. If voltage is available at the 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 CKT 241. If the fuse is open, determine if it was due to a short in the ignition feed circuit before replacing the fuse.