Refer to Engine Controls Schematic
Heated Oxygen Sensors
.
Circuit Description
The oxygen sensor heater is a device used to reduce the time that the sensor takes to go active. The PCM controls the fuel control oxygen sensor heaters using three separate drivers. The PCM uses a current monitoring driver to test the condition of the heaters. A high side driver provides HO2S bank 1 sensor 1 heater with ignition voltage. A fused ignition feed provides bank 2 sensor 1 with ignition voltage. Both heater receive ground through a low side driver (warm-up driver).
With the engine running, the PCM turns ON the high side, and the low side driver to warm-up the oxygen sensors. When the proper conditions are present, the PCM keeps the high side driver ON, turns ON the current monitor driver, and then turns OFF the warm-up driver. This allows the PCM to record a total current value for both of the fuel control heaters. If the test conditions remain stable, the PCM enters the second stage of the test. During this stage, the PCM keeps the current monitor ON, and turns OFF the high side driver. This allows the PCM to record a current value for the bank 2 sensor 1 heater circuit. The PCM subtracts the bank 2 sensor 1 current value from the total current value to determine the current value for bank 1 sensor 1. If the PCM detects a bank 1 sensor 1 current value outside the calibrated range, DTC P0135 will set.
Conditions for Running the DTC
| • | No HO2S Heater DTCs are set. |
| • | The System voltage during the current measurement is steady within 1 volt of actual system voltage. |
| • | Engine speed is between 500 and 3000 RPM. |
| • | MAF is between 4 and 30 g/s. |
| • | HO2S Overtemp control is inactive. |
Conditions for Setting the DTC
The PCM detects a bank 1 sensor 1 current value outside the calibrated range.
Action Taken When the DTC Sets
| • | The PCM illuminates the malfunction indicator lamp (MIL) during the second consecutive trip in which the diagnostic test runs and fails. |
| • | The PCM stores the conditions present when the DTC set as Freeze Frame and Fail Records data. |
Conditions for Clearing the MIL/DTC
| • | The PCM will turn the MIL OFF after the third consecutive trip in which the diagnostic runs and passes. |
| • | The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction. |
| • | The DTC can be cleared by using the scan tool Clear DTC Information function. |
Diagnostic Aids
If the condition is intermittent, refer to Intermittent Conditions in Symptoms.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Powertrain On Board Diagnostic (OBD) System Check? | -- | Go to Step 2 | |
2 |
Are DTCs P0030, P1031, and P1032 set? | -- | Go to Step 3 | |
3 |
Are DTCs P0135 and P0155 set? | -- | Go to Step 5 | Go to Step 4 |
4 | Is DTC P0135 set? | -- | Go to Step 7 | Go to Intermittent Conditions |
5 |
Does the test lamp turn ON and OFF? | -- | Go to Step 13 | Go to Step 6 |
6 | Test the HO2S bank 1 sensor 1 heater high 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 15 | Go to Step 14 |
7 | With a DMM, measure the voltage at the HO2S bank 1 sensor 1 heater high circuit. Is the voltage more than the specified value? | 10V | Go to Step 9 | Go to Step 8 |
8 | Test the HO2S bank 1 sensor 1 heater high circuit for an open circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 12 |
9 | With a DMM, measure the voltage at the HO2S bank 1 sensor 1 heater low circuit. Is the voltage near the specified value? | B+ | Go to Step 11 | Go to Step 10 |
10 | Test the HO2S bank 1 sensor 1 heater low circuit for an open circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 12 |
11 | Inspect for poor connections at the harness connector of the HO2S bank 2 sensor 1. 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 15 | Go to Step 13 |
12 | Inspect for poor connections at the harness connector of the 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 15 | Go to Step 14 |
13 | Replace HO2S bank 1 sensor 1. Refer to Heated Oxygen Sensor Replacement - Bank 1 Sensor 1 . Did you complete the replacement? | -- | Go to Step 15 | -- |
14 |
Important: The replacement PCM must be programmed. Replace the PCM. Refer Powertrain Control Module Replacement/Programming . Did you complete the replacement? | -- | Go to Step 15 | -- |
15 |
Does the scan tool display the DTC ran and passed? | -- | System OK | Go to Step 2 |
