The oxygen sensor 1 (02S-1) is an electrical source that responds to oxygen
content in the exhaust manifold. When the sensor reaches approximately 316°C
(600°F), it produces a voltage based on the difference in oxygen between the atmosphere
and exhaust gas. The PCM sends a bias voltage (399-499 mV) on the signal
line, which is pulled up through high resistance. When the O2S-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 PCM to determine a rich/lean O2S-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 10-1065 mV.
DTC P0133 sets when the O2S-1 signal rich to lean or lean to rich average
response time is too slow.
Conditions for Setting the DTC
DTC P0133 will set if the average response time of the LEAN to RICH switches
is greater than 730 ms (auto), 625 ms (manual) or the average response
time of the RICH to LEAN switches is greater than 1200 ms (auto), or 975 ms
(manual).
OR
The sum of the LEAN to RICH and RICH to LEAN average response times is greater
than 1200 ms (auto), 975 ms (manual) when:
| • | The condition exists for longer than 30 seconds. |
| • | The engine run time is greater than 3 minutes and 20 seconds. |
| • | The engine speed is between 2,350-3,000 RPM (manual) and
1800-2300 RPM (auto). |
| • | The ECT is greater than 70°C (158°F). |
| • | The TP angle is between 22-40 percent (manual) and 8-15 percent
(auto). |
| • | The loop status is closed. |
| • | The EVAP purge solenoid commanded duty cycle is greater than 80 percent. |
| • | The fuel level is greater than 10 percent. |
| • | No CKP, ECT, EVAP, fuel injector, fuel tank pressure, fuel trim, IAT,
idle speed, MAP, misfire, PCM internal fault, or TP sensor DTCs have been set. |
DTC P0133 diagnostic runs once per ignition cycle once the above conditions
have been met.
DTC P0133 is a type B DTC.
Diagnostic Aids
Possible causes of DTC P0133:
| • | An intermittent connection or corrosion in the O2S-1 harness connector
can set this DTC. Use the scan tool to monitor O2S-1 voltage with engine running
at normal operating temperature while wiggling the signal and ground wire. Make sure
the sensor is tight. |
| • | The most probable cause for DTC P0133 is contamination. Check for
obvious contamination, oil, fuel, or engine coolant, by removing the sensor.
Identify and correct the cause of the contamination if contaminated. Replace the
O2S-1. |
