Testing of Readiness Codes

Your vehicle has readiness codes as part of the onboard self-diagnostic system. Some states use these codes for testing to verify whether your vehicle’s emissions components are working properly. The codes may not be read if you go through the testing just after the battery has gone dead or been disconnected.

To check if they are set, set the power mode to ON without starting the engine. The malfunction indicator lamp will come on for several seconds. If it goes off, the readiness codes are set. If it blinks five times, the readiness codes are not set.

If you are required to have your vehicle tested before the readiness codes are set, prepare the vehicle for retesting by doing the following:
  1. Fill the gas tank to approximately 3/4 full.
  2. Park the vehicle and leave the engine off for 6 hours or more.
  3. Make sure the ambient temperature is between 40°F and 95°F (4°C and 35°C).
  4. Start the engine without touching the accelerator pedal, and let it idle for 20 seconds.
  5. Keep the vehicle in PARK (P). Increase the engine speed to 2,000 rpm, and hold it there for about 3 minutes.
  6. Let the engine idle with your foot off the accelerator for 20 seconds.
  7. Select a nearby, lightly traveled major highway where you can maintain a speed of 50 mph (80 km/h) for at least 20 minutes. Drive on the highway in DRIVE (D) . Do not use cruise control. When traffic allows, drive for 90 seconds without moving the accelerator pedal. (Vehicle speed may vary slightly; this is okay.) If you cannot do this for a continuous 90 seconds because of traffic conditions, drive for at least 30 seconds, then repeat it two more times (for a total of 90 seconds).
  8. Drive in city or suburban traffic for at least 10 minutes. When traffic conditions allow, let the vehicle coast for several seconds without using the accelerator pedal or the brake pedal.
  9. Park the vehicle and leave the engine off for 30 minutes.

The readiness codes are erased when the battery is disconnected. The codes are set again only after several days of driving under a variety of conditions.

If a testing facility determines that the readiness codes are not set, you may be requested to return at a later date to complete the test or see your dealer.

Parent topic: Maintenance