From Little Cheetah, 4 Years ago, written in Plain Text.
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  1. OBD-II Driving Cycle
  2. If you have a 96 or newer vehicle you have the OBD-II diagnostic system. This system is constantly monitoring the sensors and solenoids on the engine. If you have replaced the battery, disconnected the battery or cleared the codes after making a repair you will need to do what is called a "Driving Cycle". This will perform a diagnostic on all the systems the computer monitors. This cycle can be done in under fifteen minutes.
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  4. To perform an OBDII Driving cycle do the following:
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  6. 1. Cold Start
  7. In order to be classified as a cold start the engine coolant temperature must be below 50ºC (122ºF) and within 6ºC (11ºF) of the ambient air temperature at startup. Do not leave the key on prior to the cold start or the heated oxygen sensor diagnostic may not run.
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  9. 2. Idle
  10. The engine must be run for two and a half minutes with the air conditioner on maximum and rear defroster on. The more electrical load you can apply the better. This will test the O2 heater, Passive Air, Purge "No Flow", Misfire and if closed loop is achieved, Fuel Trim.
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  12. 3. Accelerate
  13. Turn off the air conditioner and all the other loads and apply half throttle until 88km/hr (55mph) is reached. During this time the Misfire, Fuel Trim, and Purge Flow diagnostics will be performed.
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  15. 4. Hold Steady Speed
  16. Hold a steady speed of 88km/hr (55mph) for 3 minutes. During this time the O2 response, air Intrusive, EGR, Purge, Misfire, and Fuel Trim diagnostics will be performed.
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  18. 5. Decelerate
  19. Let off the accelerator pedal. Do not shift, touch the brake or clutch. It is important to let the vehicle coast along gradually slowing down to 32km/hr (20 mph). During this time the EGR, Purge and Fuel Trim diagnostics will be performed.
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  21. 6. Accelerate
  22. Accelerate at 3/4 throttle until 88-96 km/hr (55-60mph). This will perform the same diagnostics as in step 3.
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  24. 7. Hold Steady Speed
  25. Hold a steady speed of 88km/hr (55mph) for five minutes. During this time, in addition to the diagnostics performed in step 4, the catalyst monitor diagnostics will be performed. If the catalyst is marginal or the battery has been disconnected, it may take 5 complete driving cycles to determine the state of the catalyst.
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  27. 8. Decelerate
  28. This will perform the same diagnostics as in step 5. Again, don't press the clutch or brakes or shift gears.