Circuit Description
Heated oxygen sensors (HO2S) are used for fuel control and post catalyst monitoring. Each HO2S compares the oxygen content of the surrounding air with the oxygen content in the exhaust stream. The HO2S must reach operating temperature to provide an accurate voltage signal. Heating elements inside the HO2S minimize the time required for the sensors to reach operating temperature. The engine control module (ECM) supplies the HO2S with a reference, or bias, voltage of about 450 mV. When the engine is first started the ECM operates in Open Loop, ignoring the HO2S voltage signal. Once the HO2S reaches operating temperature and Closed Loop is achieved, the HO2S generates a voltage within a range of 0-1,000 mV that fluctuates above and below bias voltage. High HO2S voltage indicates a rich exhaust stream, and low HO2S voltage indicates a lean exhaust stream. If the ECM detects that HO2S 1 voltage stays above a specified value, DTC P0132 will set.
Conditions For Running The DTC
| • | DTCs P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0122, P0123, P0125, P0171, P0172, P0300, P0336, P0340, P0341, P0455, P0500 P0601, P0602, P0606, P0641, P0722, P0723 are not set. |
| • | The Loop Status parameter is closed. |
| • | The Air Fuel Ratio parameter is between 14.5:1 and 14.8:1. |
| • | The transmission is in Drive with automatic transmission. |
Conditions For Setting The DTC
Rich Test
The ECM detects that the HO2S 1 voltage parameter is more than 786 mV for 100 seconds.
OR
Decel Fuel Cutoff Test
The ECM detects that the HO2S 1 voltage parameter is more than 586 mV for 10 seconds during decel fuel cutoff.
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. |
| • | The control module commands the Loop Status open. |
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 | Values | Yes | No | ||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Controls Connector End Views or Engine Control Module Connector End Views | ||||||||||||||||||||||
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | |||||||||||||||||||
Is the HO2S 1 voltage parameter varying above and below the specified range? | 300-600 mV | Go to Step 3 | Go to Step 4 | |||||||||||||||||||
3 |
Did the DTC fail this ignition? | -- | Go to Step 4 | Go to Intermittent Conditions | ||||||||||||||||||
4 |
Is the HO2S 1 voltage parameter within the specified range? | 400-500 mV | Go to Step 5 | Go to Step 6 | ||||||||||||||||||
5 |
Is the HO2S 1 voltage parameter more than the specified value? | 800 mV | Go to Step 8 | Go to Step 7 | ||||||||||||||||||
6 |
Important: The sensor may be damaged if the circuit is shorted to a voltage source. Test the HO2S 1 high signal 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 | Is the HO2S 1 voltage parameter less than the specified value? | 10 mV | Go to Step 10 | Go to Step 9 | ||||||||||||||||||
8 |
Important: The engine control module (ECM) may be damaged if the HO2S low signal circuit is shorted to a voltage source. Test the HO2S 1 low signal 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 | ||||||||||||||||||
9 | Test the HO2S 1 low signal circuit for an open. 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 | ||||||||||||||||||
10 |
Notice: Refer to Silicon Contamination of Heated Oxygen Sensors Notice in the Preface section.
Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 11 | ||||||||||||||||||
11 | Test for an intermittent and for a poor connection at the HO2S 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 | Test for an intermittent and for a poor connection 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 15 | Go to Step 14 | |||||||||||||||||||
13 | Replace the HO2S 1. Refer to Heated Oxygen Sensor 1 Replacement . Did you complete the replacement? | -- | Go to Step 15 | -- | ||||||||||||||||||
14 | Replace the ECM. Refer to Engine Control Module Replacement . Did you complete the replacement? | -- | Go to Step 15 | -- | ||||||||||||||||||
15 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 16 | ||||||||||||||||||
16 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK | |||||||||||||||||||
