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P3400 on the 2019 Mazda Mazda3

The bulletins listed name this code in NHTSA's summary, or are about the same components. A bulletin or a recall listed here may apply to the model year. None of it is a diagnosis.

Nobody has written a description of this code yet.

Bulletins for this model year that name P3400
SA-047-212021-10-05. Service bulletin. If you receive a customer concern about the CHECK ENGINE light coming on and DTC P3400 (cylinder deactivation system malfunction) stored, the cylinder deactivation oil control valve may be plugged with plastic debris from the oil filter wrapper. The debris may enter the center of the oil filter when poking a hole in the filter wrapper during removal, and then travel through the engine and plug the cylinder deactivation oil control valve.
SA-061-20a2020-10-05. Service bulletin. If you receive a customer concern about the CHECK IN light coming on and DTC P3400 (cylinder deactivation system malfunction) stored, the cylinder deactivation oil control valve may be plugged with plastic debris from the oil filter wrapper. The debris may enter the center of the oil filter when poking a hole in the filter wrapper during removal, and then travel through the engine and plug the cylinder deactivation oil control valve.
SA-061-202020-09-01. Service bulletin. If you receive a customer concern about the CHECK IN light coming on and DTC P3400 (cylinder deactivation system malfunction) stored, perform the inspection in the Repair Procedure.
SA-015-19a2019-05-30. Service bulletin. If you receive a customer concern with the check engine light coming on and DTC P3400 (cylinder deactivation system malfunction) stored, perform the inspection in the Repair Procedure.
SA-015-192019-04-25. Service bulletin. If you receive a customer concern with the check engine light coming on and DTC P3400 (cylinder deactivation system malfunction) stored, perform the inspection in the Repair Procedure.

5 on file from NHTSA, as of 2026-10-19. See them in the bulletin list. A bulletin lists model years: read the document for which vehicles it concerns.