In order to control the emissions, a catalytic converter converts any 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 the 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 the terminal are damaged, replace the entire oxygen sensor assembly. Do not attempt to repair the wiring, connector, or the terminals. The sensor must have a clean air reference in order for the sensor to function properly. This clean air reference is obtained by way of the oxygen sensor wire(s). Any attempt to repair the wires, connectors, or the terminals could result in the obstruction of the air reference and degrade oxygen sensor performance. Refer to Heated Oxygen Sensor Repair.
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.
The 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.
The MIL/DTC(s) can be cleared by using the scan tool.
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 Repair.
Improperly formed connectors
A poor terminal to wire connection
A damaged harness
An example test description follows:
The Powertrain OBD System Check prompts you to complete some of the basic checks and to store the freeze frame and failure records data on the scan tool if applicable. This creates an electronic copy of the data captured when the malfunction occurred. The scan tool stores this data for later reference.
This step determines if DTC P0141 is the result of a hard failure or an intermittent condition. With the ignition switch ON and the 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.
Probing terminal D of the HO2S 2 connector verifies if the voltage is available to the HO2S 2 heater.
If the voltage is available at the connector, then the connector becomes a good voltage source to check for a ground at terminal C.
This step determines if the voltage is not available at the HO2S 2 due to an open 02 fuse or open ignition feed circuit. If the fuse is open, determine if the open fuse was due to a short in the ignition feed circuit before replacing the fuse.
Monday, November 19th, 2012 AT 12:44 AM