P0141

DTC P0141 Oxygen Sensor 2 (O2S2) Heater Circuit Not Functioning

Circuit Diagram:

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

The Engine Control Module (ECM) has the ability to monitor this process by using a Oxygen sensor 2 (O2S2). The O2S2, 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 O2S2 signal will be far less active than the signal produced by the Oxygen sensor 1 (O2S1).

If the O2S2 pigtail wiring, connector, or terminal is damaged, the entire O2S2 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 O2S2 wire(s). Any attempt to repair the wires, connector, or terminals could result in the obstruction of the air reference and degrade the O2S2 performance. The ECM will check if O2S2 is functioning properly by monitoring the current to O2S2 heater. If the current is less than 0.1 ampere, DTC P0141 will set.

Conditions for Setting the DTC
- O2S2 heater current is less than 0.1 amperes.
- Engine run time is greater than 60 seconds.
- System voltage is greater than 10 volts.

Action Taken When the DTC Sets
- The Malfunction Indicator Lamp (MIL) will illuminate.
- The ECM 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.

Conditions for Clearing the MIL/DTC
- The MIL will turn off after four 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 DTC(s) can be cleared by using the scan tool.
- Disconnecting the ECM battery feed for more than 10 seconds.

Diagnostic Aids
An intermittent may be caused by a rubbed-through wire insulation or a wire contacting the exhaust.
Check for a poor connection or a damaged harness - inspect the harness connectors for the following conditions:
- Improper mating
- Broken locks
- Improperly formed
- Damaged terminals
- Poor terminal-to-wire connection
- Damaged harness

Test Description
Number(s) below refer to the step number(s) on the Diagnostic Table.
1. The On-Board Diagnostic (OBD II) 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 failure or an intermittent condition. With the ignition ON, engine OFF, the O2S2 voltage displayed on the scan tool should change within several minutes toward 0 or 1 volt, indicating that the heater is working properly.
3. Probing terminal 1 of the O2S2 connector verifies if voltage is available to the O2S2 heater.
4. If voltage is available at the connector, than it becomes a good voltage source to check for a ground at terminal 4.
5. Determines if voltage is not available at the O2S2 due to an open in the O2S2 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.

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