2001 Toyota PriusFACTORY OEM SERVICE PROCEDURE

Engine Co/HC Emission Testing: Inspection

NOTE: This check is used only to determine whether or not the idle CO/HC complies with regulations.
  1. Install Conditions 
    1. Air cleaner installed
    2. Air pipes and hoses of air induction system connected
    3. All accessories switched OFF
    4. All vacuum lines properly connected
    5. EFI system wiring connectors fully plugged
    6. Ignition timing check correctly
    7. Transmission in parking range
    8. Tachometer and CO/HC meter calibrated by hand
  2. Activate Inspection Mode And Warm Up Engine. See  PRECAUTION  .
    3. NOTE: At the accelerator opening angle of 60% or more, the engine speed is controlled at 2,250 RPM.
  3. Race Engine At 2,250 RPM For Approx. 180 Seconds 
  4. Insert CO/HC Meter Testing Probe At Least 40 CM (1.3 ft) Into Tailpipe During Idling 
    5. NOTE: When doing the 2 mode (idle and 2,250 RPM) test, these measurement order prescribed by the applicable local regulations.
  5. Immediately Check CO/HC Concentration At Idle And/or 2,250 RPM 

    Complete the measuring with 3 minutes.

  6. Stop Engine 

If the CO/HC concentration does not comply with regulations, troubleshoot in the order given below.

  • Check heated oxygen sensor operation. See DIAGNOSTIC TESTS .
  • See Fig 1 for possible causes, and then inspect and correct the applicable causes if necessary.
Fig 1: CO/HC Concentration Regulations Troubleshooting Chart
G02810575Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.