Details On DTCs

WARNING: This page is about a different car, the 2020 Mazda CX-30. However, it is still accessible from the selected car via links, so may be relevant.

DTC P2635:00 (PCM, SKYACTIV-G) DETECTION CONDITION AND POSSIBLE CAUSE

Description	Fuel transfer function malfunction
Detection condition	Determination conditions	After the vehicle is sufficiently fueled, the PCM detects that fuel in the fuel tank (sub) does not decrease and only the fuel in the fuel tank (main) decreases continuously for the specified number of times.
	Preconditions	1 min have elapsed after the ignition was switched ON (engine off) The following DTCs are not detected: P0461:00, P0462:00, P0463:00, U0121:00 or U0140:00 Low-G sensor (built-into Sophisticated Airbag Sensor (SAS) control module) signal is normal A condition in which a load of the specified value or more has not been applied to the vehicle since the ignition was switched ON (engine off) continues for the specified time.
	Drive cycle	2 * *: Because the PCM monitors the fuel decrease transition after the vehicle is sufficiently fueled, two or more drive-cycles may be necessary to store a DTC depending on the driving conditions.
	Self test type	CMDTC self test
	Sensor used	Low-G sensor (built-into Sophisticated Airbag Sensor (SAS) control module) Fuel gauge sender unit
Fail-safe function	Not applicable
Vehicle status when DTCs are output	If the fuel tank (main) becomes empty, rough idling, poor acceleration, and engine stalling occur.
Possible cause	Low-pressure side fuel delivery system malfunction Battery voltage decrease Fuel pump unit malfunction Fuel filter (high-pressure) clogged (built-into fuel pump unit) Fuel filter (low-pressure) clogged (built-into fuel pump unit) Pressure regulator (built-into fuel pump unit) malfunction Jet pump (built-into fuel pump unit) malfunction Fuel tank malfunction Clogging in hose between fuel tank (main) and fuel tank (sub) Disconnected hose between fuel tank (main) and fuel tank (sub) PCM malfunction