P1133

CIRCUIT DESCRIPTION
The Powertrain Control Module (PCM) monitors the Heated Oxygen Sensor (HO2S) activity for 100 seconds. During this test period, the PCM counts the number of times that the HO2S signal voltage crosses the rich-to-lean and the lean-to-rich thresholds. If the PCM determines that the HO2S did not switch enough times, this DTC will be set.

A lean-to-rich switch is determined when the HO2S voltage changes from less than 300 mV to more than 600 mV. A rich-to-lean switch is determined when the HO2S voltage changes from more than 600 mV to less than 300 mV.

CONDITIONS FOR RUNNING THE DTC
^ DTCs P0101, P0102, P0103, P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0125, P0128, P0201, P0202-P0206, P0410, P0440, P0442, P0443, P0446, P0449, or P1441 are not set.
^ The system voltage is more than 9 volts.
^ The engine is running in Closed Loop.
^ The engine is running for at least 3.3 minutes.
^ The ECT is more than 70°C (158°F).
^ The TPS angle is more than 2 percent.
^ The engine speed is between 1,300-3,000 RPM.
^ The MAF is between 13-29 g/s.
^ The above conditions are stable for 3 seconds.

CONDITIONS FOR SETTING THE DTC
^ The PCM monitors fewer than 25 rich-to-lean and 25 lean-to-rich switches for the HO2S 1.
^ The condition is present for a 100-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.
^ Use a scan tool in order to clear the MIL and the DTC.

TEST DESCRIPTION

Steps 1-6:

Steps 7-12:

The numbers below refer to the step numbers on the diagnostic table.
2. This step checks for correct sensor activity. When in Closed Loop fuel control, the HO2S voltage should rapidly swing above and below the bias voltage.
4. This step checks the PCM and the HO2S high signal and HO2S low reference circuits between the PCM and the HO2S connector for correct operation.