P0133

Schematic:

The heated oxygen (HO2S) bank 1 sensor 1 is threaded into the cylinder 1, 3, 5 exhaust manifold (cylinders 1, 3, 5 are closest to front of dash). The sensor is an electrical source that responds to oxygen content in the exhaust manifold. When the sensor reaches approximately 316°C (600°F), it is fully functional and produces a voltage based on the difference in oxygen between the atmosphere and exhaust gas. The ECM sends a 450 mV bias voltage on the signal line, which is pulled up through high resistance. When the HO2S bank 1 sensor 1 is cold, it produces no voltage and has extremely high internal resistance. The internal resistance of the sensor is much greater than the resistance of the bias pull-up resistor. However, when the sensor heats up, it produces voltage that overrides the bias voltage. This voltage is read by the ECM to determine a rich/lean HO2S bank 1 sensor 1 signal used to adjust injector pulse width. Under normal conditions, low sensor voltage means high oxygen content/lean air-fuel mixture and vice versa. Normal sensor readings will fluctuate between 60 mV and 1080 mV. DTC P0133 will set if the HO2S bank 1 sensor 1 average lean to rich or rich to lean response time is too slow.

DTC PARAMETERS
DTC P0133 will set if the average response time for the sum of the HO2S bank 1 sensor 1 LEAN to RICH and RICH to LEAN switches is greater than 1.3 seconds when:
^ Condition exists for 21 samples (about 28 seconds)
^ Engine speed is between 1600 and 2400 rpm
^ Engine load is between 25 and 60%
^ Bank 1 is in closed loop
^ Long term fuel trim is active
^ System is not purging OR has been purging for at least 10 seconds
^ Calculated exhaust gas temperature is greater than 350°C (662°F)
^ EVAP diagnostics are not running
^ HO2S heater performance diagnostics have been run
^ No CAM, ECT, EVAP purge solenoid, fuel trim, HO2S bank 1 sensor 1 heater, MAF or misfire DTCs have been set

DTC P0133 diagnostic runs once per ignition cycle once the above conditions have been met.

P0133 is a type B DTC.

DIAGNOSTIC AIDS
Make sure no corrosion is present in the HO2S bank 1 sensor 1 harness connector. Make sure no exhaust leaks exist between the bank 1 engine head and HO2S bank 1 sensor 2. Each of these two conditions may Set P0133.

The most probable cause for DTC P0133 is a weak, aging or contaminated sensor. Check for obvious contamination (oil, fuel or engine coolant) by removing sensor. Source and fix the cause of the contamination if contaminated. Replace the HO2S bank 1 sensor 1.