Table 1: | HO2S Voltages |
Heating elements inside the heated oxygen sensor (HO2S) minimize the time required for the sensors to reach operating temperature and to provide an accurate voltage signal. A low side driver within the powertrain control module (PCM) is pulse width controlled to provide current to the heater elements. During warm-up, the PCM will pulse the heaters ON-OFF to prevent thermal shock to the sensor components from moisture in the exhaust system. The PCM will not allow continuous HO2S heating until calibrated limits of time, temperature, and intake airflow have been reached. The PCM continuously monitors the HO2S heater current draw and operating state by briefly turning OFF the heater low side driver at regular intervals. The PCM calculates the HO2S heater element resistance based on the actual heater current. If the PCM detects that the HO2S heater element resistance is too high, this DTC will set.
Each HO2S heater has the following circuits:
• | HO2S heater ignition 1 voltage |
• | HO2S heater low control |
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 |
• | DTCs P0030, P0036, P0050, P0056, P0117, P0118, P2414, P2415 are not set. |
• | The engine is operating for more than 90 seconds. |
• | The ignition 1 voltage is between 10.5-16 volts. |
• | The engine coolant temperature (ECT) is more than -20°C (-4°F). |
• | The system is not in fuel cut-off mode for at least 90 seconds. |
• | DTCs P0135 and P0155 run continuously once the above conditions are met. |
• | The calculated internal resistance of the HO2S is more than 110 ohms for more than 90 seconds after an engine start. |
OR |
• | The calculated internal resistance of the HO2S is more than 110 ohms for more than 15 seconds. |
• | The calculated internal resistance of the HO2S is more than 200 ohms for more than 1 second. |
• | The air/fuel ratio (A/F) sensor heater internal output voltage is 0.76 volt or more. |
• | The A/F sensor heater internal output voltage is 0.24 volt or less. |
• | The PCM illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails. |
• | The PCM records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the PCM stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the PCM records the operating conditions at the time of the failure. The PCM writes the conditions to the Freeze Frame and updates the Failure Records. |
• | The PCM turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail. |
• | A last test failed, or current DTC, clears when the diagnostic runs and does not fail. |
• | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic. |
• | Use a scan tool in order to clear the MIL and the DTC. |
• | Use the J-35616 Connector Test Adapter Kit for any test that requires probing the PCM harness connector or a component harness connector. |
• | The Loop Status for the respective bank will default to Open when the DTC is current. |
• | The wide band sensors do not toggle or switch like a switching HO2S. The HO2S signals will be relatively stable for an idling engine. |
• | For an intermittent condition, refer to Intermittent Conditions . |
• | The following table illustrates the typical voltages for the HO2S circuits: |
| |||||
---|---|---|---|---|---|
HO2S Circuit | Voltage | ||||
Heater Control | Less than 0.5 V | ||||
Heater Supply Voltage | B+ | ||||
Reference Voltage | 3.3-3.8 V | ||||
Low Reference | 5.9-6.4 V | ||||
Pump Current | 4.8-5.3 V | ||||
Input Pump Current | 3.3-3.8 V |
The numbers below refer to the step numbers on the diagnostic table.
This step tests for high resistance in the ignition 1 voltage circuit of the HO2S. If the DMM does not display near battery voltage, repair the high resistance in the ignition 1 voltage circuit.
This step tests the HO2S heater control circuit for a high resistance. Six amps through the DMM is normal when the HO2S heater control circuit is commanded ON with a scan tool. A high resistance in the circuit will cause the amperage to be less than 1 amp. Test the HO2S heater control circuit for a high resistance if the DMM displays a reading of less than 1 amp.
This step tests the HO2S input pump current circuit for a wire to wire short to the reference voltage circuit or a condition internal to the PCM. If the resistance measured between the circuits is more than 110,000 ohms, the PCM and the circuits are OK.
This step isolates the condition. Test for a wire to wire short between the HO2S input pump current and reference voltage circuits, if any continuity exists between the circuits.
Inspect the HO2S connector for water intrusion, corrosion, and bent or damaged terminals.
Inspect the PCM connectors for water intrusion, corrosion, and bent or damaged terminals.
Step | Action | Values | Yes | No | ||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Powertrain Control Module Connector End Views or Engine Controls Connector End Views | ||||||||||||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |||||||||||
2 |
Important: DTC P0135 is for bank 1 sensor 1 - rear and DTC P0155 is for bank 2 sensor 1 - front.
Does the DTC fail this ignition? | -- | Go to Step 4 | Go to Step 3 | ||||||||||
3 |
Does the DTC fail this ignition? | -- | Go to Step 4 | Go to Diagnostic Aids | ||||||||||
Does the voltage measure at the specified value? | B+ | Go to Step 5 | Go to Step 17 | |||||||||||
Is the amperage more than the specified value? | 1 A | Go to Step 6 | Go to Step 11 | |||||||||||
6 | Measure the voltage between the HO2S reference voltage circuit and a good ground with a DMM. Is the voltage within the specified range? | 3.3-3.8 V | Go to Step 7 | Go to Step 12 | ||||||||||
7 | Measure the voltage between the HO2S low reference circuit and a good ground with a DMM. Is the voltage within the specified range? | 5.9-6.4 V | Go to Step 8 | Go to Step 13 | ||||||||||
8 | Measure the voltage between the HO2S input pump current circuit and a good ground with a DMM. Is the voltage within the specified range? | 3.3-3.8 V | Go to Step 9 | Go to Step 14 | ||||||||||
Is the resistance less than the specified value? | 110 Kohms | Go to Step 10 | Go to Step 15 | |||||||||||
Is the resistance at the specified value? | OL | Go to Step 16 | Go to Step 18 | |||||||||||
11 | Test the HO2S heater control circuit for a high resistance. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 21 | Go to Step 16 | ||||||||||
12 | Test the HO2S reference voltage circuit for an open, a high resistance, or a short to ground. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 21 | Go to Step 16 | ||||||||||
13 | Test the HO2S low reference circuit for one of the following conditions:
Did you find and correct the condition? | -- | Go to Step 21 | Go to Step 16 | ||||||||||
14 | Test the HO2S input pump current circuit for an open, a high resistance, or a short to voltage. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 21 | Go to Step 16 | ||||||||||
Test for shorted terminals and for poor connections at the HO2S. Refer to Testing for Intermittent Conditions and Poor Connections and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 21 | Go to Step 19 | |||||||||||
Test for shorted terminals and for poor connections at the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 21 | Go to Step 20 | |||||||||||
17 | Repair the open or high resistance in the HO2S heater ignition 1 circuit. Refer to Wiring Repairs . Did you complete the repair? | -- | Go to Step 21 | -- | ||||||||||
18 | Repair the short between the HO2S input pump current circuit and the HO2S reference voltage circuit. Did you complete the repair? | -- | Go to Step 21 | -- | ||||||||||
19 | Replace the HO2S. Refer to the appropriate procedure: Did you complete the replacement? | -- | Go to Step 21 | -- | ||||||||||
20 |
Did you complete the replacement? | -- | Go to Step 21 | -- | ||||||||||
21 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 22 | ||||||||||
22 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK |