P0304 on the 2019 Mazda CX-5
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.
| 01-001-23a | 2023-03-03. Service bulletin. Some customers may complain about a poor acceleration and rough idling or the CHECK ENGINE light ON with DTC P0301:00, P0302:00, P0303:00, P0304:00.NOTE: Only turbo engines are applicable; non-turbo engines are NOT applicable. In most cases, DTCs P030X stores, but sometimes not. Sometimes the CHECK ENGINE light does not recognize this engine concern. This is caused by the variable valve in the exhaust manifold seizing and causing the exhaust port to become hot and the exhaust valve seat to wear unevenly, resulting in compression leakage. To eliminate this concern, the design of the exhaust manifold has been modified. |
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| SA-022-19 | 2019-05-30. Service bulletin. If you receive a customer complain of lack of power, rough idle, engine noise with stored DTC's P0340:00, P0304:00, P3400:00, P349B:00, and/or P3498:00, perform the following. |
| 01-007-19-3541 | 2019-02-19. Service bulletin. When the engine is started for the first time after parking the vehicle overnight in cold conditions (below 32 degrees Fahrenheit / 0 degrees Celsius), some vehicles may exhibit a rough idle and/or the check engine light on with any of the following DTC(s) stored in memory. P0300 - Random misfire detected P0301 - Cylinder No. 1 misfire detected P0302 - Cylinder No. 2 misfire detected P0303 - Cylinder No. 3 misfire detected P0304 - Cylinder No.4 misfire detected. This may be caused by frozen water accumulated in the main silencer, restricting exhaust flow. |
3 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.