P0141
DTC P0141CIRCUIT 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 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 supplies the HO2S with a reference, or bias, voltage of about 450 mV. The HO2S generates a voltage within a range of 0-1,000 mV that fluctuates above and below bias voltage once the sensor reaches operating temperature. A high HO2S voltage output indicates a rich fuel mixture. A low HO2S voltage output indicates a lean mixture. Heating elements inside the HO2S minimize the time required for the sensors to reach operating temperature, and to provide an accurate voltage signal. The PCM controls the HO2S 2 heater low control circuit with a low side driver. The HO2S 2 heater diagnostic monitors the amount of time it takes for the HO2S 2 to generate a voltage that is higher or lower than bias voltage by a calibrated amount. If the PCM detects that the HO2S 2 voltage has not changed more than 74 mV from bias voltage within a calibrated amount of time, DTC P0141 will set.
Each HO2S 2 has the following circuits:
- An HO2S 2 high signal circuit
- An HO2S 2 low reference circuit
- An HO2S 2 heater ignition voltage circuit
- An HO2S 2 heater low control circuit
- An HO2S low reference circuit
CONDITIONS FOR RUNNING THE DTC
- DTCs P0036, P0101, P0102, P0103, P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0137, P0138, P0140, P0201, P0202, P0203, P0204, P0205, P0206, P0442, P0443, P0446, P0449, P0455, P0496, P1106, P1107, P1111, P1112, P1114, P1115, P2135 are not set.
- The Start Up ECT parameter is less than 35°C (95°F).
- The Start Up IAT parameter is less than 35°C (95°F).
- The difference between the Start Up ECT parameter and the Start Up IAT parameter is less than 6°C (11°F).
- The MAF Sensor parameter averages less than 23 9/5.
- The HO2S 1 voltage parameter is between 400-500 mV at start-up.
- The system voltage is between 9-18 volts.
CONDITIONS FOR SETTING THE DTC
The PCM detects that the HO2S 2 voltage has not moved above or below bias voltage by more than 74 mV within a calibrated amount of time.
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
