DTC P0135: O2 Sensor 1/1 Heater Failure, DTC P0141: O2 Sensor 1/2 Heater Failure, DTC P0155: O2 Sensor 2/1 Heater Failure Or DTC P0161: O2 Sensor 2/2: Heater Failure: Testing

WARNING: This page is about a different car, the 2003 Dodge Dakota. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: Turn the ignition off. Wait a minimum of 8 minutes for O2 sensor to cool down before continuing test.

Turn ignition on, with engine off. With the DRBIII(R) scan tool, actuate the O2 heater test. With the DRBIII(R) scan tool, monitor O2 sensor voltage for at least 2 minutes. Does the voltage stabilize between 0.1 and 0.3 of a volt during the heater test? If yes, see INTERMITTENT CONDITION under SELF-DIAGNOSTIC SYSTEM. If no, go to next step.
Turn the ignition off. Disconnect the O2 sensor harness connector. Measure the resistance of the O2 heater element at the O2 sensor connector (component side). On a four O2 sensor system the resistance value for 1/1 and 2/1 O2 heater elements is 3.3-4.1 ohms at 70° F (21.1°C). On a four O2 sensor system the resistance value for 1/2 and 2/2 O2 heater elements is 4.0-5.0 ohms at 70°F (21.1°C). On a two O2 sensor system the resistance value for the 1/1 and 1/2 O2 heater elements is 4.0-5.0 ohms at 70°F (21.1°C). Is the resistance value within the listed specification? If yes, go to next step. If no, replace the O2 sensor.
The O2 heater supply circuit may be a fused ASD relay output or an O2 sensor heater relay output, depending on the O2 sensor being tested. Ignition on, engine not running and the O2 sensor still disconnected. With the DRBIII(R) scan tool, actuate the O2 heater test. Measure the voltage on the O2 heater supply circuit at the O2 sensor harness connector. Is the voltage more than 10.0 volts? If yes, go to next step. If no, repair the open in the O2 sensor heater supply circuit.
Turn the ignition off. Disconnect the PCM harness connectors. Remove the O2 heater relay, if it applies to the O2 sensor being tested. Measure the resistance of the O2 heater control circuit (PWM) from the O2 sensor to the PCM harness connector if it applies to the O2 sensor being tested or measure the resistance of the (K127) O2 heater relay control circuit from the O2 heater relay to the PCM harness connector, if it applies to the O2 sensor being tested. Is the resistance less than 5.0 ohms? If yes, go to next step. If no, repair the excessive resistance in the O2 heater control circuit.
Before beginning this test, verify what type of heated O2 sensor is being tested, either the PWM heated O2 sensor or the heater relay controlled heated O2 sensor. Remove the O2 heater relay if it applies to the type of heated O2 sensor being tested. Measure the resistance between ground and the of the O2 heater control circuit (PWM) at the O2 sensor harness connector if it applies to the O2 sensor being tested or measure the resistance between ground and the (K127) O2 heater relay control circuit if it applies to the heated O2 sensor being tested. Is the resistance less than 100 ohms? If yes, repair the short to ground in the O2 heater control circuit. If no, go to next step.

NOTE: Before continuing, disconnect the PCM harness connectors and check the related wiring terminals for corrosion, damage or terminal push out. Repair as necessary.

Using the wiring diagram as a guide, inspect the wire harness and connectors. Visually inspect the related wire harness. Look for any chafed, pierced, pinched, or partially broken wires. Visually inspect both the component and the PCM connectors. Pay particular attention to all power and ground circuits. If there are no possible causes remaining, replace and program the PCM. See PROGRAMMING .