P1133

Schematic:

CIRCUIT DESCRIPTION

The 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 lean to rich thresholds. If the PCM determines that the HO2S did not switch enough times, DTC P1133 will be set. A lean to rich switch is determined when the HO2S voltage changes from less than 300 mV to greater 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
^ None of the following DTCs are set:
- Throttle Position (TP) sensor
- Evaporative Emissions (EVAP) system
- Intake Air Temperature (IAT) sensor
- Manifold Absolute Pressure (MAP) sensor
- Fuel trim
- Fuel injector circuit
- EGR pintle position
- Mass Air Flow (MAF) sensor
- Engine Coolant Temperature (ECT) sensor
- Crankshaft Position (CKP) sensor
- Heated Oxygen Sensor (HO2S) 1 heater circuit
^ The mass air flow is between 10 and 30 g/s.
^ The ECT is more than 50°C (122°F).
^ The engine run time is more than 60 seconds.
^ The engine speed is between 1000 and 3000 RPM.
^ The engine is running in Closed Loop.

CONDITIONS FOR SETTING THE DTC
^ The PCM monitors fewer than 40 rich to lean and 40 lean to rich switches for the HO2S 1.
^ The above conditions are present for a 100 second monitoring period.

ACTION TAKEN WHEN THE DTC SETS
^ The PCM will illuminate the Malfunction Indicator Lamp (MIL) during the second consecutive trip in which the diagnostic test has been run and failed.
^ The PCM will store conditions which were present when the DTC set as Freeze Frame and Failure Records data.
^ If the misfire is determined to be catalyst damaging, the PCM will flash the MIL.

CONDITIONS FOR CLEARING THE MIL/DTC
^ The PCM will turn OFF the MIL during the third consecutive trip in which the diagnostic has been run and passed.
^ The History DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
^ The DTC can be cleared by using a scan tool.

DIAGNOSTIC AIDS
A poor connection in the HO2S heater ignition feed or ground circuit may cause the DTC to set. Check HO2S heater circuitry for intermittent malfunctions or poor connections. It connections and wiring are OK and the DTC continues to set, replace the HO2S 1.

Reviewing the Fail Records vehicle mileage since the diagnostic test last tailed may help determine how often the condition that caused the DTC to be set occurs. This may assist in diagnosing the condition.


TEST DESCRIPTION

Steps 1 - 6:

Steps 7 - 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 low circuit is shorted to ground the HO2S voltage will be less than 400 mV when the 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. This vehicle is equipped with a PCM which utilizes an Electrically Erasable Programmable Read Only Memory (EEPROM). When the PCM is replaced, the new PCM must be programmed.