P1153

CIRCUIT DESCRIPTION
The powertrain control module (PCM) monitors the heated oxygen sensor (HO2S) activity. Within a 100 second test period, the PCM counts the number of times that the HO2S signal voltage crosses the rich-to-lean-to-rich thresholds. If the PCM determines that the HO2S did not switch enough times, DTC P1153 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-P0206, P0300, P0410, P0440, P0442, P0443, P0446, P0449, or P1441 are not set.

CONDITIONS FOR SETTING THE DTC
^ The PCM monitors fewer than 55 lean-to-rich and rich-to-lean switches for bank 2 HO2S 1.
^ The HO2S voltage remains between 300-600 millivolts.
^ The conditions are present for 2 minutes after Closed Loop enable.

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
If the condition is intermittent, refer to Intermittent Conditions. Intermittent Conditions

TEST DESCRIPTION

Steps 1-11:

Steps 12-16:

The numbers below refer to the step numbers on the diagnostic table.
2. When the system is operating correctly, the HO2S voltage should toggle above and below the specified values.
5. If the HO2S low signal circuit is shorted to ground, the HO2S voltage will be less than 400 mV when the HO2S high signal circuit is jumped to ground.
6. The specified value is what is measured on a correctly operating system.
7. The specified value is what is measured on a correctly operating system.
14. The new PCM must be programmed.