P0135

DTC P0135

CIRCUIT DESCRIPTION
The heated oxygen sensor (HO2S) heater reduces the time required for the oxygen sensor to reach operating temperature and maintains the operating temperature during extended idle periods. When the ignition is turned to the ON position, ignition voltage is supplied directly to the sensor heater. The engine control module (ECM) controls the heater operation by first modulating the control circuit to ground when the sensors are cold. This prevents the possibility of thermal shock to the sensor, from condensation build-up on the sensor, by controlling the sensors rate of heating. After a predetermined amount of time, the ECM commands the heaters ON continuously. Once the sensor reaches operating temperature, the ECM may modulate the heater control circuit to ground, to maintain a desired temperature.

The ECM measures the HO2S sensing cell internal resistance. If the ECM detects that the HO2S sensing cell internal resistance is too high, this DTC sets.

DTC DESCRIPTORS
This diagnostic procedure supports the following DTCs:
- DTC P0135 HO2S Heater Performance Bank 1 Sensor 1
- DTC P0155 HO2S Heater Performance Bank 2 Sensor 1

CONDITIONS FOR RUNNING THE DTC

Condition 1
- Before the ECM can report DTC P0135 or P0155 failed, DTCs P0030, P0031, P0032, P0050, P0051, P0052, P0101, P0102, P0103, P0121, P0122, P0123, P0131, P0132, P0151, P0152, P0221, P0222, P0223, P0335, P0336, P0338, P167A, P167B, P2237, P2240, P2243, P2247, P2251, and P2254 must run and pass.
- The ignition 1 voltage is between 10.5-18 volts.
- The HO2S is at operating temperature.
- The ECM internal sensing element resistance test is enabled.
- DTC P0135 and P0155 run continuously once the above conditions are met for 1 minute for CTS.
- DTC P0135 and P0155 run continuously once the above conditions are met for 30 seconds for SRX and STS.

Condition 2
- Before the ECM can report DTC P0135 or P0155 failed, DTCs P0030, P0031, P0032, P0050, P0051, P0052, P0101, P0102, P0103, P0121, P0122, P0123, P0131, P0132, P0151, P0152, P0221, P0222, P0223, P0335, P0336, P0338, P167A, P167B, P2237, P2240, P2243, P2247, P2251, and P2254 must run and pass.
- The ignition 1 voltage is between 10.5-18 volts.
- The ECM internal sensing element resistance test is enabled.
- The fuel injectors are not disabled.
- If the engine is operating and then the ignition is turned OFF, the engine must be OFF for at least 5 minutes before the next start-up for the diagnostic to run.
- The engine coolant temperature (ECT) at start up is more than -10°C (+14°F).
- The HO2S is at operating temperature.
- DTC P0135 and P0155 run continuously once the above conditions are met for 2 minutes.

CONDITIONS FOR SETTING THE DTC

Condition 1
- The internal ECM HO2S sensing element resistance is less than a predetermined threshold.
- The condition exists for more than 4 seconds.

Condition 2
- The ECM detects that the calculated HO2S temperature is less than a predetermined threshold.
- The condition exists for more than 4 seconds.

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 fails.
- 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 4 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.

DIAGNOSTIC AIDS
- Use the J 35616 Connector Test Adapter Kit for any test that requires probing the ECM harness connector or a component harness connector.
- The lower connector of the ECM is connector C1 and the upper connector of the ECM is connector C2. Refer to Computers and Control Systems Component Views.
- The front wide band sensors do not toggle or switch like a switching HO2S. The front HO2S signals will be relatively stable for an idling engine.
- High resistance in any of the HO2S circuits could cause this DTC to set.
- For an intermittent condition, refer to Intermittent Conditions. Intermittent Conditions

HO2S Voltages:

- The table illustrates the typical voltages for the HO2S circuits:

TEST DESCRIPTION

Step 1 - Step 7:

Step 8 - Step 16:

The numbers below refer to the step numbers on the diagnostic table.
2. This step determines if the condition exists. If there is an HO2S circuit condition, the ECM commands open loop for the applicable sensor.
4. This step tests for a bias voltage across the reference voltage circuit and the low reference circuit of the HO2S. The bias voltage that you are measuring, is the voltage difference between the reference voltage circuit and the low reference circuit. If there is a condition with the reference voltage circuit or the low reference circuit of the HO2S, the bias voltage will be more than or less than the specified value.
5. This step is testing the ignition 1 voltage circuit of the HO2S for high resistance. If the voltage at the test lamp probe is not B+, there is a high resistance condition with the circuit.
10. This step inspects the harness connector for water intrusion, corrosion, and bent or damaged pins.
11. This step inspects the harness connector for water intrusion, corrosion, and bent or damaged pins.