Theory Of Operation

This continuous diagnostic is used to detect when fuel control has not changed from open loop to closed loop control. A count down timer is initiated at engine start. The length of the timer is based on the starting engine coolant temperature. The timer will decrement as long as the enable conditions are met. Once the timer has expired, the fuel control system is expected to be in closed loop operation. If the fuel control system does not go closed loop within the calibrated time, the diagnostic will fail.