Circuit Description
The wide band heated oxygen sensor (HO2S) measures the amount of oxygen in the exhaust stream more quickly and accurately than the switching style HO2S. The wide band sensor consists of an oxygen sensing cell, an oxygen pumping cell, and a heater. The exhaust gas sample passes through a diffusion gap between the sensing cell and the pumping cell. The engine control module (ECM) supplies a signal voltage to the HO2S and uses this voltage as a reference to the amount of oxygen in the exhaust system. An electronic circuit within the ECM controls the pump current through the oxygen pumping cell in order to maintain a constant signal voltage. The ECM monitors the voltage variation on the signal circuit, and attempts to keep the voltage constant by increasing or decreasing the amount of current flow or reversing the direction of the current flow to the pumping cell. By measuring the direction and amount of current required to maintain the signal voltage, the ECM can determine the concentration of oxygen in the exhaust. The signal voltage is displayed as a lambda value. A lambda value of 1 is equal to a stoichiometric air fuel ratio of 14.7:1. Under normal operating conditions, the lambda value will remain around 1. When the system is lean, the oxygen level will be high and the lambda value will be high, or more than 1. When the system is rich, the oxygen level is low and the lambda value will be low, or less than 1. The ECM uses this information to maintain the proper air/fuel ratio. If the ECM detects an HO2S circuit that is shorted to voltage, DTC P0132 will set for bank 1 sensor 1, or DTC P0152 will set for bank 2 sensor 1.
Conditions for Running the DTC
| • | DTCs P0030, P0031, P0032, P0036, P0037, P0038, P0050, P0051, P0052, P0056, P0057, P0058, P0132, P0133, P0135, P0137, P0138, P0139, P0140, P0141, P0152, P0153, P0155, P0157, P0158, P0159, P0160, P0161, P1137, P1138, P1157, P1158, P2231, P2234, P2237, P2240, P2243, P2247, P2251, P2254, P2626, P2629, P167A, P167B are not set. |
| • | The engine is running. |
Conditions for Setting the DTC
The ECM detects that one of the following HO2S circuits is shorted to voltage:
| • | The input pump current circuit |
| • | The output pump current circuit |
| • | The reference voltage circuit |
| • | The low reference circuit |
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 Views Reference: Engine Controls Connector End Views or Engine Control Module Connector End Views | ||||||||||||||||
1 | Did you perform the Diagnostic System Check-Vehicle? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information | ||||||||||||
2 |
Does the lambda value react immediately to the above action? | -- | Go to Step 3 | Go to Step 4 | ||||||||||||
3 |
Did the DTC fail this ignition? | -- | Go to Step 4 | Go to Intermittent Conditions | ||||||||||||
4 |
Did you find and correct the condition? | -- | Go to Step 18 | Go to Step 5 | ||||||||||||
5 |
Did you find and correct the condition? | -- | Go to Step 18 | Go to Step 6 | ||||||||||||
6 |
Is the voltage more than the specified value? | 4.5 V | Go to Step 10 | Go to Step 7 | ||||||||||||
7 | Measure the voltage from the HO2S low reference circuit on the engine harness side connector to a good ground with a DMM. Refer to Circuit Testing in Wiring Systems. Is the voltage more than the specified value? | 3 V | Go to Step 11 | Go to Step 8 | ||||||||||||
8 |
Important: The normal open circuit voltage of both the HO2S input pump current and output pump current circuits is approximately 10-65 millivolts. Test the following HO2S circuits for a short to voltage:
Refer to Circuit Testing , Wiring Repairs , and Heated Oxygen Sensor Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 18 | Go to Step 9 | ||||||||||||
9 |
Important: Disconnecting the engine control module (ECM) may eliminate a circuit short. Is the resistance between any HO2S circuit and all other HO2S circuits less than the specified value? | ∞ | Go to Step 15 | Go to Step 12 | ||||||||||||
10 |
Important: The normal open circuit voltage of the HO2S reference voltage circuit is 2.8-3.1 volts. Test the HO2S reference voltage circuit for a short to voltage. Refer to Circuit Testing , Wiring Repairs , and Heated Oxygen Sensor Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 18 | Go to Step 14 | ||||||||||||
11 |
Important: The normal open circuit voltage of the HO2S low reference circuit is 2.4-2.7 volts. Test the HO2S low reference circuit for a short to voltage. Refer to Circuit Testing , Wiring Repairs , and Heated Oxygen Sensor Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 18 | Go to Step 14 | ||||||||||||
12 | The HO2S may be detecting a rich exhaust condition. Inspect for one of the following conditions:
Repair any of the above or similar engine conditions, as necessary. Did you find and correct the condition? | -- | Go to Step 18 | Go to Step 13 | ||||||||||||
13 | Test for poor connections and shorted terminals at the affected 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 18 | Go to Step 16 | ||||||||||||
14 | Test for poor connections and shorted terminals at the ECM. 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 18 | Go to Step 17 | ||||||||||||
15 | Repair the short between the affected HO2S circuits. Refer to Circuit Testing and Heated Oxygen Sensor Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 18 | -- | ||||||||||||
16 | Replace the affected HO2S. Refer to Heated Oxygen Sensor Replacement - Bank 1 Sensor 1 or Heated Oxygen Sensor Replacement - Bank 2 Sensor 1 . Did you complete the replacement? | -- | Go to Step 18 | -- | ||||||||||||
17 | Replace the ECM. Refer to Engine Control Module Replacement . Did you complete the replacement? | -- | Go to Step 18 | -- | ||||||||||||
18 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 19 | ||||||||||||
19 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information | System OK | ||||||||||||
