Some 2017-2019 MKZ vehicles equipped with a 2.0 HEV engine may exhibit a fuel filler door unable to be opened or closed with or without an illuminated malfunction indicator (MIL) and DTC P04B5. This may occur when the fuel door is pressed or obstructed while the fuel door release latch is operating. If the fuel filler door is unable to be closed, a message displays during the third drive cycle and the DTC P04B5 will set. Before performing Workshop Manual (WSM) diagnosis, reset the system by pressing the fuel filler door release switch and wait 12 seconds for reset. The fuel door release latch should be heard when the motor is in motion. Review fuel filler door for locking tab operation. If the fuel filler door is operating properly, it should not be replaced. Advise the customer about the correct operation of the fuel filler door.
