P0133

DTC P0132 Heated Oxygen Sensor (HO2S) Circuit Slow Response (Bank 1, Sensor 1):

Heated Oxygen Sensor (HO2S 1) Circuit:

CIRCUIT DESCRIPTION
The Vehicle Control Module-A (VCM-A) supplies a voltage of approximately 0.45 volt (450 mV) between VCM-A pins "BL2" and "BL7".

NOTE: If this voltage is measured using a 10 megohm digital voltmeter, the voltage may read as low as 0.32 volt. The Heated Oxygen Sensor (HO2S) varies the voltage within a range of about 1 volt (1000 mV) if the exhaust is rich, to as low as 0.10 volt (10 mV) if the exhaust is lean.

The VCM-A monitors the Heated Oxygen Sensor (HO2S) activity for 100 seconds after "Closed Loop." During the monitor period, the VCM-A counts the number of times that the HO2S switches from rich to lean and from lean to rich and adds the amount of time it took to complete all switches. With this information, an average time for all switches can be determined. If the average time to switch is too slow, a DTC P0133 will be set.

When HO2S temperature is below 360°C (600°F), the sensor will not produce any voltage and will behave like an open circuit. This will result in "Open Loop" operation.

The HO2S heater provides for faster sensor warm-up which allows the sensor to become active in a shorter period of time and remain active during long extended idle. DTC P0133 determines if the HO2S is functioning properly by checking its response time.

DTC P0133 WILL SET WHEN
^ No Throttle Position (TP) sensor DTCs.
^ No Evaporative Emissions (EVAP) System DTCs.
^ No Intake Air Temperature (IAT) sensor DTCs.
^ No Manifold Absolute Pressure (MAP) DTCs.
^ No Exhaust Gas Recirculation (EGR) DTCs.
^ No fuel trim DTCs.
^ No Engine Coolant Temperature (ECT) sensor DTCs.
^ DTC P0135 (HO2S heater) not set.
^ "Closed Loop."
^ HO2S voltage low threshold 0.300 and high threshold 0.600V.
^ Throttle position is between 10% and 20%.
^ HO2S average transition time Lean/Rich is greater than 100 msec. Rich/Lean is greater than 125 msec.

ACTION TAKEN (VCM-A WILL DEFAULT TO)
The VCM-A will turn "ON" the Malfunction Indicator Lamp (MIL) after the second test failure.

DTC PO133 WILL CLEAR WHEN
The VCM-A will turn the MIL "OFF" after three consecutive trips without a fault condition present. A history DTC will be cleared if no fault conditions have been detected for forty warm-up cycles [coolant temperature has risen 22°C (40°F) from start-up coolant temperature and engine coolant temperature exceeds 71°C (160°F) that same ignition cycle] or the Tech 1 clearing feature has been used.

DTC CHART TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.
1. This step checks for other DTC(s).
2. This step checks for physical damage to engine components and converter.
3. This step checks the fuel injector and isolates the HO2S.

DIAGNOSTIC AIDS
Check HO2S heater operation.