P0135

DTC P0135, P0141, P0155, or P0161

Circuit Description

The powertrain control module (PCM) supplies a bias voltage of approximately 450 mV on the heated oxygen sensor (HO2S) high and low signal circuits. When you turn ON the ignition, battery voltage is supplied to the HO2S heater. As the heater reaches the operating temperature, the HO2S voltage responds by changing from a bias voltage range to the normal operation. Typically, as the HO2S reaches the operating temperature, the HO2S voltage goes from a bias voltage to a voltage below 300 mV. Depending on the exhaust gas content, the HO2S voltage can go above 450 mV.

Depending on the cumulative air flow, the PCM runs the heater test only during a cold start, and only once an ignition cycle. When you start the engine, the PCM monitors the HO2S voltage. When the HO2S voltage goes above or below the bias range threshold, the PCM determines how much time the process took. If the PCM detects that the process took too much time for the HO2S to enter into normal operating range, a DTC sets. This time is based on the amount of air that flows into the engine.


DTC Descriptors

This diagnostic procedure supports the following DTCs.

- DTC P0135 Heater Performance Bank 1 Sensor 1

- DTC P0141 Heater Performance Bank 1 Sensor 2

- DTC P0155 Heater Performance Bank 2 Sensor 1

- DTC P0161 Heater Performance Bank 2 Sensor 2


Conditions for Running the DTC

- DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0121, P0122, P0123, P0125, P0128, P0200, P0300, P0443, P0496. P1111, P1112, P1114, P1115, P1121, or P1122 are not set.

- The engine coolant temperature (ECT) is more than 50°C (122°F).

- The ignition 1 voltage is between 10-18 volts.

- The engine speed is between 500-3,000 RPM.

- The engine has been running for at least 120 seconds.

- The mass air flow (MAF) is between 3-40 g/s.

- The intrusive tests are not in progress.

- The scan tool output controls are not active.

- DTCs P0135, P0141. P0155, and P0161 run twice per ignition cycle when the above conditions are met.

Conditions for Setting the DTC

The HO2S heater circuit current remains between
0.25-3.125 amps for a predetermined amount of time.

OR

The HO2S heater circuit resistance is between
3.21-9.81 ohms when the ECT and IAT are both less
than 8°C (46°F) at engine start-up.


Action Taken When the DTC Sets

- The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and tails.

- The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.


Conditions for Clearing the MIL/DTC

- The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.

- A current DTC, Last Test Failed, clears when the diagnostic runs and passes.

- A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.

- Clear the MIL and the DTC with a scan tool.


Test Description

DTC P0135, P0141, P0155, or P0161 Steps 1-9:

DTC P0135, P0141, P0155, or P0161 Steps 10-13:

The numbers below refer to the step numbers on the diagnostic table.

2. Before you perform this test, allow the engine to cool If the sensor is at the operating temperature, the HO2S voltage will stay high or low. If the HO2S voltage stays between 300-700 mV, the HO2S heater is inoperative.

3. If more than one HO2S DTC is set, the HO2S fuse may be open. Test all the related circuits going to all the heated oxygen sensors for a short to ground. If all the wiring is OK, you may need to disconnect each HO2S one at a time in order to locate a shorted sensor.

4. This step verifies whether an ignition voltage is available at the sensor.

5. This step verifies whether ground is available at the sensor.

6. This step verifies whether the HO2S heater element is internally open.

7. Inspect the ignition 1 voltage circuits at the underhood electrical center for poor connections.

8. If more than one heater DTC sets, test the ground circuits for an open.