P0141

Diagnostic Chart:

Wiring Diagram:

Circuit Description

The heated oxygen sensors are used to minimize the amount of time required for closed loop fuel control operation and to allow accurate catalyst monitoring. The oxygen sensor heater greatly decreases the amount of time required for fuel control (HO2S sensor 1) to become active. The oxygen sensor heater is required by the catalyst monitor (HO2S sensor 2) to maintain a sufficiently high temperature. This allows accurate exhaust oxygen content readings from the engine.

Conditions for Setting the DTC

^ Resistor voltage less than 2.5 volts with the heater off.

^ Resistor voltage greater than 0.31 volts with the heater on.

^ One of the above conditions present for 5 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 buffer.

Conditions for Clearing the MIL/DTC

^ The MIL will turn OFF after three consecutively passing cycles without a fault present.

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

^ DTCs can be cleared by using a scan tool or by disconnecting the PCM battery feed.

Diagnostic Aids

Check for any of the following conditions:

^ A poor connection at the PCM. Inspect harness connectors for backed out terminal, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to the wire connection.

^ A damaged wiring harness. Inspect the wiring harness for damage. If the harness appears to be OK, observe the HO2S 2 display on the scan tool while moving connectors and wiring harnesses related to the sensor. A change in the HO2S 2 display will indicate the location of the fault.

If a DTC P0141 cannot be duplicated, the information included in the Freeze Frame data can be useful in determining vehicle operating conditions when the DTC was first set.

If any wiring repairs need to be made, Refer to Repair Procedures in Electrical Diagrams.

Test Description

The numbers below refer to the step numbers in the Diagnostic Table.

1. The Powertrain OBD System Check prompts the technician to complete some basic checks and store the freeze frame 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 in the scan tool for later reference.

2. Determine if the fault is present.

3. The HO2S 2 is powered by the IG fuse located in the Junction Block.

5. Measure the resistance of the heater portion of the HO2S 2.