P0140

DTC P0140

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. Low HO2S voltage indicates a lean exhaust stream. This diagnostic will only run once per ignition cycle. If the ECM detects that the HO2S voltage remains within the bias voltage range, DTC P0140 sets for HO2S bank 1 sensor 2, or DTC P0160 sets for HO2S bank 2 sensor 2.

DTC DESCRIPTORS
This diagnostic procedure supports the following DTCs:
- DTC P0140 HO2S Circuit Insufficient Activity Bank 1 Sensor 2
- DTC P0160 HO2S Circuit Insufficient Activity Bank 2 Sensor 2

CONDITIONS FOR RUNNING THE DTC
- DTCs P0054, P0060, P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0120, P0121, P0122, P0123, P0128, P0141, P0161, P0201, P0202, P0203, P0204, P0205, P0206, P0207, P0208, P0220, P0442, P0443, P0446, P0449, P0455, P0496, P1258, P1516, P2101, P2135, P2176 are not set.
- The Engine Run Time parameter is more than 300 seconds.
- The Fuel Tank Level Remaining parameter is more than 10 percent.
- The Loop Status is closed.
- The Ignition 1 Signal parameter is between 10-18 volts.
- This diagnostic runs continuously once the above conditions are met.

CONDITIONS FOR SETTING THE DTC
- The ECM detects that the affected HO2S voltage parameter is between 410-490 mV for 150 seconds.
- The TP Indicated Angle parameter changes more than 5 percent within 1 second, 6 times.

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.

TEST DESCRIPTION

Step 1 - Step 9:

Step 10 - Step 18:

The number below refers to the step number on the diagnostic table.
3. If the voltage is varying above and below the specified value, the condition is not present.