DTC P04C9: General Description
A cumulative fuel amount that has been injected since the last refueling should not exceed the fuel tank capacity in general as long as the fuel fill door system is fully functional since a cumulative amount of injected fuel that is monitored by the powertrain control module (PCM) is reset at the time of each refueling. When the PCM is unable to detect refueling, the cumulative amount of injected fuel monitored by the PCM eventually exceeds the fuel tank capacity because either of the following reasons: refueling was made without the fuel fill door switch being pressed or refueling was not detected by the PCM even the switch was being pressed. When this occurs, the PCM detects a malfunction of the fuel fill door system and stores a DTC.