Circuit Description
The heated oxygen sensor (HO2S) is a sensor used to detect oxygen-content in the exhaust. The powertrain control module (PCM) supplies the sensor with a signal circuit and a ground circuit. The PCM supplies a bias voltage between the circuits. The sensor varies the voltage based on the oxygen content in the exhaust. When the exhaust stream is lean (more oxygen), the sensor produces a low voltage signal. When the exhaust stream is rich (less oxygen), the sensor produces a high voltage signal. The PCM monitors the HO2S signal during Closed Loop. To correct for rich or lean conditions the following must occur:
| • | The PCM adjusts the injector pulse width. |
| • | The diagnostic runs once per key cycle. |
| • | The HO2S 2 signal voltage is within 100 mV of the bias amount at start-up. |
Conditions for Running the DTC
| • | DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0125, P0141, P0201-P0208, P0410, P0440, P0442, P0443, P0446, P0449, P1415, P1416, or P1441 are not set. |
| • | The system voltage is between 9-18 volts. |
| • | The engine is running for 3 minutes. |
| • | The Closed Loop is enabled. |
| • | The exhaust gas recirculation (EGR) flow diagnostic test is not active. |
| • | The secondary air injection (AIR) diagnostic test is not active. |
Conditions for Setting the DTC
The HO2S bank 1 sensor 2 signal voltage remains within 400-500 mV for approximately 80 seconds.
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. |
Diagnostic Aids
Notice: Do not solder heated oxygen sensor wires. Soldering the wires will result in the loss of the air reference to the sensor. Refer to Engine Electrical for proper wire and connection repair techniques.
Notice: Use the connector test adapter kit J 35616-A for any test that
requires probing the following items:
• The PCM harness connectors • The electrical center fuse/relay cavities • The component terminals • The component harness connector
Check for the following conditions:
| • | Inspect the harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal-to-wire connections. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. |
| • | A damaged harness--Inspect the wiring harness for damage. If the harness appears to be OK, observe the scan tool while moving connectors and wiring harnesses related to HO2S bank 1 sensor 2 sensor. A change in the display will indicate the location of the malfunction. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. |
| • | For intermittent conditions, refer to Intermittent Conditions . |
Reviewing the Failure Records vehicle mileage since the diagnostic test last failed may assist in diagnosing the condition. The information may help determine how often the condition that set the DTC occurs.
Test Description
The number below refers to the step number on the diagnostic table.
Step | Action | Values | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics | ||||||||||
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | |||||||
2 | Are any DTCs set other than DTC P0140? | -- | Go to Step 3 | |||||||
3 |
Does the scan tool indicate HO2S bank 1 sensor 2 voltage vary outside the specified values? | 300-500 mV | Go to Step 4 | Go to Step 5 | ||||||
4 |
Does the scan tool indicate the DTC failed this ignition? | -- | Go to Step 5 | Go to Diagnostic Aids | ||||||
Does the scan tool indicate an HO2S bank 1 sensor 2 voltage below the specified value? | 150 mV | Go to Step 7 | Go to Step 6 | |||||||
6 |
Did you find and correct the condition? | -- | Go to Step 10 | Go to Step 9 | ||||||
7 |
Did you find and correct the condition? | -- | Go to Step 10 | Go to Step 8 | ||||||
8 | Replace HO2S bank 1 sensor 2. Refer to Heated Oxygen Sensor Replacement - Bank 1 Sensor 1 and Heated Oxygen Sensor Replacement - Bank 1 Sensor 2 . Did you complete the replacement? | -- | Go to Step 10 | -- | ||||||
9 | Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the replacement? | -- | Go to Step 10 | -- | ||||||
10 |
Does the DTC run and pass? | -- | Go to Step 11 | Go to Step 2 | ||||||
11 | With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK | |||||||
