Fuel Delivery and Air Induction: Description and Operation

Fig. 3 Electronic Fuel Injection system.:

SELF DIAGNOSIS SYSTEM

By analyzing current flow through the electronic control circuits, the EFI computer detects malfunctions or abnormalities of the system sensors and actuators. When the computer detects a malfunction, it energizes a ``Check Engine'' lamp on the instrument panel and a malfunction or diagnostic code is stored in the computer memory. The warning lamp remains illuminated only as long as the malfunction continues, and is turned off once the malfunction has been corrected. However, the diagnostic code remains stored in the computer memory as long as battery voltage is supplied to the computer, and codes pertaining to both existing and intermittent malfunctions can be accessed for system service and during system diagnosis.