P1134

CIRCUIT DESCRIPTION
The Powertrain Control Module (PCM) continuously monitors the Heated Oxygen Sensor (HO2S) activity. The PCM counts the number of times that the HO2S responds by switching from a rich state to a lean state. Next, the PCM adds the amount of time the HO2S took to complete all transitions during the 100-second test period. With this information, an average time for all transitions can be determined. The PCM then divides the rich-to-lean average by the lean-to-rich average to obtain a ratio. If the HO2S transition time ratio is not within range, this Diagnostic Trouble Code (DTC) will set. The setting of this DTC indicates that the oxygen sensor is not responding as expected, to changes in exhaust oxygen content.

CONDITIONS FOR RUNNING THE DTC
^ DTCs P0101, P0102, P0103, P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0125, P0128, P0201, P0202, P0203, P0204, P0205, P0206, P0300, P0410, P0440, P0442, P0443, P0446, P0449, or P1441 are not set.
^ The Mass Air Flow (MAF) is between 10-30 g/s.
^ The Engine Coolant Temperature (ECT) is more than 50°C (122°F).
^ The engine run time is more than 60 seconds.
^ The engine speed is between 1,000-3,000 RPM.
^ The engine is running in Closed Loop.

CONDITIONS FOR SETTING THE DTC
^ The above conditions are present for a 100-second monitoring period.
^ The ratio of average response times is not between 6-0.5.

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 1-3:

Steps 4-12:

The numbers below refer to the step numbers on the diagnostic table.
4. This step test for conditions which may cause the DTC to set with a good heated oxygen sensor. Correct any of the described conditions, if present.
7. Before replacing the HO2S, inspect for silicon contamination.