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 powertrain control module (PCM) supplies the HO2S with a reference, or bias, voltage of about 450 mV. When the engine is first started the PCM 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; low HO2S voltage indicates a lean exhaust stream. If the PCM detects an HO2S voltage that stays above a specified value, DTCs P0132 or P0152 will set.
• | DTCs P0102, P0103, P0107, P0108, P0112, P0113, P0117, P0118, P0120, P0200, P0220, P0404, P0405, P1125, P1404, P1514, P1515, P1516, P1518, P2108, P2135 are not set. |
• | The Loop Status parameter is closed. |
• | The Ignition 1 Signal parameter is between 10-18 volts. |
• | The Fuel Tank Level Remaining parameter is more than 10 percent. |
• | The TP Indicated Angle parameter is between 3-70 percent more than the value observed at idle. |
OR
• | DTCs P0102, P0103, P0107, P0108, P0112, P0113, P0117, P0118, P0120, P0200, P0220, P0404, P0405, P1125, P1404, P1514, P1515, P1516, P1518, P2108, P2135 are not set. |
• | The Loop Status parameter is closed. |
• | The Ignition 1 Signal parameter is between 10-18 volts. |
• | The Fuel Tank Level Remaining parameter is more than 10 percent. |
• | The Engine Run Time parameter is more than 30 seconds. |
• | The Decel. Fuel Cutoff parameter is active for more than 4 seconds. |
The PCM detects that the affected HO2S voltage parameter is more than 900 mV for 165 seconds.
OR
The PCM detects that the affected HO2S voltage parameter is more than 250 mV for 5 seconds.
• | 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. |
• | 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. |
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: Powertrain Control Module Connector End Views or Engine Controls Connector End Views | ||||||||||||||||||||||
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | |||||||||||||||||||
Is the HO2S 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 voltage parameter within the specified range? | 400-500 mV | Go to Step 5 | Go to Step 6 | ||||||||||||||||||
5 |
Is the HO2S voltage parameter less than the specified value? | 100 mV | Go to Step 7 | Go to Step 8 | ||||||||||||||||||
6 | Test the HO2S high signal circuit for a short to the HO2S heater low control circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 10 | ||||||||||||||||||
7 |
Is the HO2S voltage parameter less than the specified value? | 100 mV | Go to Step 9 | Go to Step 11 | ||||||||||||||||||
8 | Test the HO2S high 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 17 | Go to Step 14 | ||||||||||||||||||
9 | Test the HO2S low signal circuit for a short to the HO2S heater low control circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 12 | ||||||||||||||||||
10 |
Important: The sensor may be damaged if the circuit is shorted to a voltage source. Test the HO2S 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 17 | Go to Step 14 | ||||||||||||||||||
11 | Test the HO2S 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 17 | Go to Step 14 | ||||||||||||||||||
12 |
Notice: Refer to Silicon Contamination of Heated Oxygen Sensors Notice in the Preface section.
Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 13 | ||||||||||||||||||
13 | Test for an intermittent and for a poor connection at the HO2S. 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 17 | Go to Step 15 | ||||||||||||||||||
14 | Test for an intermittent and for a poor connection at 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 17 | Go to Step 16 | ||||||||||||||||||
15 | 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 17 | -- | ||||||||||||||||||
16 | Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the replacement? | -- | Go to Step 17 | -- | ||||||||||||||||||
17 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 18 | ||||||||||||||||||
18 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK |
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 of the exhaust stream. When the vehicle is first started, the powertrain control module (PCM) operates in an Open Loop mode, ignoring the HO2S signal voltage when calculating the air-to-fuel ratio. The PCM circuitry that monitors the HO2S, generates a reference or bias voltage of 450 mV when the sensor is cold, high resistance. Once the HO2S warms up, the HO2S generates a voltage within a range of 0-1,000 mV, depending on the exhaust gas oxygen content. High HO2S voltage output indicates a rich fuel mixture. Low HO2S voltage output indicates a lean mixture. Once fueling goes Closed Loop, the HO2S voltage will fluctuate above and below the bias voltage. A heating element inside the HO2S reduces the time required for the sensor to reach operating temperature, and provide an accurate voltage signal.
This DTC is designed to detect an HO2S voltage that remains at a high voltage for more than a specified number of seconds during the test conditions.
• | DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0200, P0300, P0351-P0358, P0400, P0401, P0404, P0405, P0410, P0440, P0442, P0443, P0446, P0449, P0452, P0453, P1120, P1125, P1220, P1221, P1258, P1404, P1441, P1514, P1515, P1516, P1517, or P1518 are not set. |
• | The secondary air injection (AIR) and the exhaust gas recirculation (EGR) diagnostics are not active. |
• | The ignition voltage is more than 9 volts. |
• | The fuel system is operating in Closed Loop. |
• | The accelerator pedal position (APP) indicated angle is between 3-70 percent. |
• | The fuel level is more than 10 percent. |
• | DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0200, P0300, P0351-P0358, P0400, P0401, P0404, P0405, P0410, P0440, P0442, P0443, P0446, P0449, P0452, P0453, P1120, P1125, P1220, P1221, P1258, P1404, P1441, P1514, P1515, P1516, P1517, or P1518 are not set. |
• | The AIR and the EGR diagnostics are not active. |
• | The ignition voltage is more than 9 volts. |
• | The fuel system is operating in Closed Loop. |
• | The fuel level is more than 10 percent. |
• | The decel fuel cut-off (DFCO) mode is enabled for more than 2 seconds. |
• | The HO2S signal voltage remains above 775 mV. |
• | The Rich Test Enable conditions are present for 200 seconds. |
• | The HO2S signal voltage remains above 540 mV for 4.5 seconds. |
• | The Decel Fuel Cut Off Test Enable conditions are present for 5 seconds during the DFCO mode. |
• | 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 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. |
The numbers below refer to the step numbers on the diagnostic table.
When the system is operating correctly, the HO2S 1 voltage should toggle above and below the specified values. You may need to operate the vehicle within the Freeze Frame conditions and Conditions for Setting the DTC in order to duplicate the malfunction that was detected by the PCM.
The specified value is what is measured on a correctly operating system.
Step | Action | Values | Yes | No | ||||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Powertrain Control Module Connector End Views or Engine Controls Connector End Views | ||||||||||||||||||||||
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | |||||||||||||||||||
Is the HO2S voltage fixed at more than the value specified? | 976 mV | Go to Step 4 | Go to Step 3 | |||||||||||||||||||
3 |
Did the DTC fail this ignition? | -- | Go to Step 4 | Go to Intermittent Conditions | ||||||||||||||||||
Does the HO2S voltage measure within the specified range? | 351-551 mV | Go to Step 5 | Go to Step 6 | |||||||||||||||||||
5 |
Does the voltage measure less than the specified value? | 20 mV | Go to Step 8 | Go to Step 7 | ||||||||||||||||||
6 | Test the HO2S 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 13 | Go to Step 10 | ||||||||||||||||||
7 | Test the HO2S low signal 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 13 | Go to Step 10 | ||||||||||||||||||
8 |
Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 9 | ||||||||||||||||||
9 | Inspect for poor connections at the harness connector of the affected HO2S. 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 13 | Go to Step 11 | ||||||||||||||||||
10 | 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 13 | Go to Step 12 | ||||||||||||||||||
11 |
Important: Before replacing a contaminated HO2S determine and repair the cause of the contamination. 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 13 | -- | ||||||||||||||||||
12 | Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the replacement? | -- | Go to Step 13 | -- | ||||||||||||||||||
13 |
Did the DTC run and pass? | -- | Go to Step 14 | Go to Step 2 | ||||||||||||||||||
14 | With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK |