Malfunction Indicator Lamp: Description and Operation

Malfunction Indicator Lamp (MIL) Indication (In relation to Readiness Codes)
The vehicle has certain "readiness codes" that are part of the on-board diagnostics for the emissions systems. If the vehicle's battery has been disconnected or gone dead, these codes are erased. In some states, part of the emissions testing is to make sure these codes are set. If all of them are not set, the test cannot be completed.

To check if the readiness codes are set, turn the ignition switch ON (II), but do not start the engine. The MIL will come on for 15 - 20 seconds. If it then goes off, the readiness codes are set. If it blinks several times, the readiness codes are not set completely. To reset each code, drive the vehicle or run the engine as described in the procedures to set them.