Circuit Description
The heated oxygen sensor (HO2S) must reach operating temperature to provide an accurate voltage signal. A heating element inside the HO2S minimizes the time required for the sensor to reach operating temperature. Voltage is provided to the heater by the ignition 1 voltage circuit through a fuse. With the engine running, ground is provided to the heater by the HO2S heater low control circuit, through a low side driver within the engine control module (ECM). The ECM commands the heater ON or OFF to maintain a specific HO2S operating temperature range. The ECM determines the temperature by measuring the current flow through the heater. When the heater is in the ON state, the ECM will pulse the heater OFF for a duration of 50 ms, once per second. The ECM calculates the heater resistance on a cold start. This diagnostic will only run once per ignition cycle. If the ECM detects that the heater calculated resistance is not within the expected range, the following DTCs will set:
| • | DTC P0053 for HO2S sensor 1 |
| • | DTC P0054 for HO2S sensor 2 |
DTC Descriptors
This diagnostic procedure supports the following DTCs:
| • | DTC P0053 HO2S Heater Resistance Sensor 1 |
| • | DTC P0054 HO2S Heater Resistance Sensor 2 |
Conditions for Running the DTC
| • | DTCs P0112, P0113, P0116, P0117, P0118, P0128, P2610 are not set. |
| • | The ignition is OFF for more than 10 hours. |
| • | The ECT Sensor parameter is between -30 and +45°C (-22 and +113°F) at engine start-up. |
| • | The ECT Sensor parameter minus the IAT Sensor parameter is less than 8°C (14°F) at engine start-up. |
| • | The engine is started. |
| • | The above conditions are met for up to 1 second. |
| • | This diagnostic runs one time per valid cold start when the above conditions are met. |
Conditions for Setting the DTC
The ECM detects that the affected HO2S heater calculated resistance is not within an expected range at engine start-up for one second.
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. |
Test Description
The number below refers to the step number on the diagnostic table.
Step | Action | Value(s) | Yes | No | ||||
|---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine 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 | Is DTC P0053 set? | -- | Go to Step 4 | Go to Step 3 | ||||
3 |
Is the HO2S heater current parameter within the specified range? | 0.25-1.375 A | Go to Step 5 | Go to Step 6 | ||||
4 |
Is the HO2S heater current parameter within the specified range? | 0.25-3.125 A | Go to Step 5 | Go to Step 6 | ||||
5 |
Did the DTC fail this ignition? | -- | Go to Step 6 | Go to Testing for Intermittent Conditions and Poor Connections | ||||
6 |
Is the fuse open? | -- | Go to Step 7 | Go to Step 8 | ||||
7 | Test the ignition 1 voltage circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 22 | Go to Step 10 | ||||
8 |
Does the test lamp illuminate? | -- | Go to Step 9 | Go to Step 19 | ||||
Does the test lamp blink once per second? | -- | Go to Step 11 | Go to Step 12 | |||||
10 |
Important: Perform the following test on all HO2S' which are supplied voltage by the suspect circuit. Test the ignition 1 voltage circuit on the sensor side of the HO2S connector for a short to ground. Refer to Circuit Testing . Is any sensor shorted to ground? | -- | Go to Step 20 | Go to Testing for Intermittent Conditions and Poor Connections | ||||
11 | Measure the resistance of the following circuits with a DMM:
Refer to Circuit Testing . Is the resistance of either circuit more than the specified value? | 3 ohms | Go to Step 18 | Go to Step 16 | ||||
12 | Is the test lamp on steady? | -- | Go to Step 13 | Go to Step 14 | ||||
13 | Test the HO2S heater low control circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 22 | Go to Step 17 | ||||
14 | Test the HO2S heater low control circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 22 | Go to Step 15 | ||||
15 | Test the HO2S heater low control circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 22 | Go to Step 17 | ||||
16 | Test for shorted terminals and for poor connections at the HO2S. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 22 | Go to Step 20 | ||||
17 | Test for shorted terminals and for poor connections at the engine control module (ECM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 22 | Go to Step 21 | ||||
18 | Repair the circuit with high resistance. Refer to Wiring Repairs . Did you complete the repair? | -- | Go to Step 22 | -- | ||||
19 | Repair the open or high resistance in the ignition 1 voltage circuit. Refer to Wiring Repairs . Did you complete the repair? | -- | Go to Step 22 | -- | ||||
20 | Replace the affected HO2S. Refer to Heated Oxygen Sensor Replacement - Bank 1 Sensor 1 or Heated Oxygen Sensor Replacement - Bank 1 Sensor 2 . Did you complete the replacement? | -- | Go to Step 22 | -- | ||||
21 | Replace the ECM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 22 | -- | ||||
22 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 23 | ||||
23 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK | |||||
