Circuit Description
The heated oxygen sensor (HO2S) produces a voltage that varies between 100-900 mV under normal operating conditions. The engine control module (ECM) produces a bias voltage on the HO2S signal circuit of 420-480 mV. The reference ground for the sensor is provided through the ECM. The ECM monitors the signal voltage to determine if the exhaust is lean or rich. The oxygen sensor voltage is high when the exhaust is rich, and low when the exhaust is lean. The ECM constantly monitors the HO2S signal during the Closed Loop operation. If the ECM detects that the HO2S internal resistance remains above a specified threshold for longer than a predetermined amount of time, DTC P0141 will set for bank 1 sensor 2, or DTC P0161 will set for bank 2 sensor 2.
Conditions for Running the DTC
| • | DTCs P0021, P0024, P0030, P0031, P0032, P0036, P0037, P0038, P0050, P0051, P0052, P0056, P0057, P0058, P0101, P0102, P0103, P0106, P0107, P0108, P0116, P0117, P0118, P0121, P0122, P0123, P0125, P0128, P0131, P0132, P0134, P0135, P0137, P0138, P0139, P0140, P0141, P0151, P0152, P0154, P0155, P0157, P0158, P0159, P0160, P0161, P0201-0208, P0221, P0222, P0223, P0261, P0262, P0264, P0265, P0267, P0268, P0270, P0271, P0273, P0274, P0276, P0277, P0279, P0280, P0282, P0283, P0300, P0301-0308, P0335, P0336, P0340, P0341, P0345, P0346, P0351-0358, P0365, P0366, P0390, P0391, P0442, P0443, P0446, P0449, P0453, P0454, P0455, P0458, P0459, P0496, P2231, P2234, P2237, P2240, P2243, P2247, P2251, P2254, P2626, P2629 are not set. |
| • | The Engine Speed parameter is more than 500 RPM. |
| • | The Ignition 1 Signal parameter is more than 10 volts. |
| • | The Engine Run Time parameter is more than 3 minutes. |
| • | The HO2S Bank 1 Sensor 2 or HO2S Bank 2 Sensor 2 heater parameter is 1-99 percent. |
Conditions for Setting the DTC
The HO2S resistance is greater than 1,100 ohms for more than 40 samples during a 45-second monitoring period.
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 View 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 voltage react immediately when performing 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 |
Is the voltage less than the specified value? | 25 mV | Go to Step 5 | Go to Step 7 | ||||||
5 |
Is the voltage less than the specified value? | 25 mV | Go to Step 6 | Go to Step 8 | ||||||
6 |
Is the resistance of either circuit more than the specified value? | 5 ohms | Go to Step 11 | Go to Step 9 | ||||||
7 | Test the HO2S high signal circuit for an open or high resistance. 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 14 | Go to Step 10 | ||||||
8 | Test the HO2S low signal circuit for an open or high resistance. 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 14 | Go to Step 10 | ||||||
9 | Test for intermittent and poor connections at the 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 14 | Go to Step 12 | ||||||
10 | Test for intermittent and poor connections at the engine control module (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 14 | Go to Step 13 | ||||||
11 | Repair the circuit with high resistance. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 14 | -- | ||||||
12 | Replace the affected HO2S. Refer to Heated Oxygen Sensor Replacement - Bank 1 Sensor 2 or Heated Oxygen Sensor Replacement - Bank 2 Sensor 2 . Did you complete the replacement? | -- | Go to Step 14 | -- | ||||||
13 | Replace the ECM. Refer to Engine Control Module Replacement . Did you complete the replacement? | -- | Go to Step 14 | -- | ||||||
14 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 15 | ||||||
15 | 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 | ||||||
