P1133

DTC P1133 Heated Oxygen System (HO2S) System Fault - Too Few Rich/Lean Or Lean/Rich Transitions, Insufficient Activity (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 "BL21" 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 (100 mV) if the exhaust is lean.

When the 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 P1133 determines if the HO2S is functioning properly by monitoring the number of L/R and R/L switches.

DTC P1133 WILL SET WHEN
^ No fuel trim DTCs.
^ 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 Engine Coolant Temperature (ECT) sensor DTCs.
^ DTC P0135 (oxygen heater) not set.
^ "Closed Loop."
^ Oxygen voltage between 0.300 and 0.600V.
^ Throttle position is between 10% and 20%.
^ L/R switches is less than 30.
^ R/L switches is less than 30.

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

DTC P1133 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.