P1133

CIRCUIT DESCRIPTION
The VCM supplies a voltage of about 0.45 volt between the HO2S High and HO2S Low circuits. (If measured with a 10 megaohm digital voltmeter, this may read as low as 0.32 volt.) The Heated Oxygen Sensor (HO2S 1) varies the voltage within a range of about 1.0 volt if the exhaust is rich, down through about 0.10 volt if the exhaust is lean.

The sensor is like an open circuit and produces no voltage when it is below 360°C (600°F). An open oxygen sensor circuit or cold oxygen sensor causes an Open Loop operation.

The HO2S heater provides for a faster sensor warm-up which allows the sensor to become active in a shorter period of time and remain active during a long extended idle.

The DTC P1133 determines if the HO2S functioning properly by the monitoring the number of the L/R and the R/L switches. The DTC P1133 is a type B DTC.

CONDITIONS FOR SETTING THE DTC
The following conditions sets the DTC:

^ No fuel trim DTCs.
^ L/R switches less than 30.
^ R/L switches less than 30.
^ No TP sensor DTCs.
^ No Evaporative Emissions (EVAP) DTCs.
^ No IAT sensor DTCs.
^ No MAP DTCs No EGR DTCs.
^ No ECT sensor DTCs.
^ The DTC P0135 not set.
^ Closed Loop.
^ HO2S voltage between 0.300 volts and 0.600 volts.
^ Throttle position is greater than 10% but less than 20%.

ACTION TAKEN WHEN DTC SETS
The VCM turns on the Malfunction Indicator Lamp (MIL) after the second test failure.

CONDITIONS FOR CLEARING THE MIL/DTC
The VCM turns the MIL off after 3 consecutive driving trips without a fault condition present. A history DTC will clear if no fault conditions have been detected for 40 warm-up cycles (coolant temperature has risen 40°F from the start-up coolant temperature and the engine coolant temperature exceeds 160°F during that same ignition cycle) or the scan tool clearing feature has been used.

DIAGNOSTIC AIDS
Check the HO2S heater operation.

Never solder the HO2S wires. For proper wire and connector repairs, refer to Wiring Repairs.

TEST DESCRIPTION
The numbers below refer to the step numbers in the diagnostic table.

2. If the TP signal is less than 0.2 volt, then the fault is present.
3. This step simulates the DTC P0123: (high voltage) - If the VCM recognizes the high signal voltage, the VCM and the wiring are OK.
4. The VCM recognizes the voltage as over 4 volts, indicating that the TP sensor signal circuit and the VCM are OK.
5. This simulates a high signal voltage in order to check for an open in the TP sensor signal circuit.
6. This step checks the 5 volt reference circuit for an open, short to ground, or a poor connection or a faulty VCM.