Circuit Description
Heating elements inside the heated oxygen sensors (HO2S) minimize the time required for the sensors to reach operating temperature and provide an accurate voltage signal. The powertrain control module (PCM) controls the HO2S heater operation with a low side driver. The sensors receive power from a fused ignition 1 voltage circuit. If the PCM detects that an HO2S heater low control circuit condition is incorrect, the following DTCs will set:
| • | P0030 for Bank 1 Sensor 1 |
| • | P0036 for Bank 1 Sensor 2 |
| • | P0050 for Bank 2 Sensor 1 |
Conditions for Running the DTC
| • | The ECT Sensor parameter is more than 60°C (140°F). |
| • | The MAF Sensor parameter is between 5-30 g/s. |
| • | The Engine Speed parameter is between 500-3000 RPM. |
| • | The Engine Run Time parameter is more than 3 minutes. |
| • | The system voltage is between 10-18 volts. |
Conditions for Setting the DTC
The PCM detects the heater circuit is open or shorted.
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 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. |
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Powertrain Control Module Connector End Views and Engine Controls Component Views | ||||
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | |
2 |
Important: An open OXY SEN fuse may cause multiple heated oxygen sensor (HO2S) DTCs to set.
Does the HO2S Heater parameter move above the specified value? | 0.00 A | Go to Step 3 | Go to Step 4 |
3 |
Did the DTC fail this ignition? | -- | Go to Step 4 | Go to Intermittent Conditions |
4 | Inspect the OXY SEN fuse for an open. Is the fuse open? | -- | Go to Step 5 | Go to Step 6 |
5 | Test each HO2S 1 ignition 1 voltage circuit branch for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 19 | Go to Step 10 |
6 |
Is the voltage less than the specified value? | 5 V | Go to Step 7 | Go to Step 11 |
7 |
Important: Use a known good ground. Do not use the HO2S heater low control circuit or HO2S low signal circuit. Probe the HO2S heater ignition 1 voltage circuit, on the engine harness side, with a test lamp that is connected to a good ground. Refer to Probing Electrical Connectors in Wiring Systems. Does the test lamp illuminate? | -- | Go to Step 8 | Go to Step 16 |
8 | Connect the test lamp between the HO2S ignition 1 voltage circuit and the HO2S heater low control circuit, on the engine harness side. Does the test lamp illuminate? | -- | Go to Step 12 | Go to Step 9 |
9 |
Does the test lamp blink ON and OFF? | -- | Go to Step 14 | Go to Step 13 |
10 |
Important: Perform the following test on each HO2S. Test the ignition 1 voltage circuit on the sensor side of the HO2S connector for a short to ground. Refer to Circuit Testing in Wiring systems. Is any sensor shorted to ground? | -- | Go to Step 17 | Go to Intermittent Conditions |
11 |
Important: The normal voltage on any HO2S heater low control circuit is 4.4-4.6 volts. Test the HO2S heater low control circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 19 | Go to Step 15 |
12 | Test the affected HO2S heater low control circuit for a short to ground or a short to the HO2S low signal circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 19 | Go to Step 15 |
13 | Test the affected HO2S heater low control circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 19 | Go to Step 15 |
14 | Test for poor connections and shorted terminals at the HO2S. Refer to Testing for Intermittent Conditions and Poor Connections , Connector Repairs , and Heated Oxygen Sensor Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 19 | Go to Step 17 |
15 | Test for poor connections and shorted terminals at the powertrain control module (PCM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 19 | Go to Step 18 |
16 | Repair the open or high resistance on the affected HO2S heater ignition 1 voltage circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 19 | -- |
17 |
Notice: Refer to Heated Oxygen Sensor Resistance Learn Reset Notice in the Preface section. Replace the affected HO2S. Refer to Heated Oxygen Sensor Replacement - Bank 1 Sensor 1 , Heated Oxygen Sensor Replacement - Bank 1 Sensor 2 or Heated Oxygen Sensor Replacement - Bank 2 Sensor 1 . Did you complete the replacement? | -- | Go to Step 19 | -- |
18 | Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the replacement? | -- | Go to Step 19 | -- |
19 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 20 |
20 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK | |
