# P0304 on the 2021 Honda Accord

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 P0304

- [11037690](https://open.wenmarpro.com/bulletins/11037690), 2026-10-01: Service Bulletin \- Under certain conditions, the cylinder head gasket effectiveness may be reduced which may cause vehicles to experience overheating, coolant loss, and/or misfire. In some cases, DTCs P0300 through P0304 may also be stored \(DTCs are not required for repair\).
- [11037687](https://open.wenmarpro.com/bulletins/11037687), 2026-10-01: Service Bulletin \- Under certain conditions, the cylinder head gasket effectiveness may be reduced which may cause vehicles to experience overheating, coolant loss, and/or misfire. In some cases, DTCs P0300 through P0304 may also be stored \(DTCs are not required for repair\).
- [11036424](https://open.wenmarpro.com/bulletins/11036424), 2026-08-27: Dealer Message \- Under certain conditions, the cylinder head gasket effectiveness may be reduced which may cause vehicles to experience overheating, coolant loss, misfire, and/or DTCs P0300 through P0304 stored.
- [11036405](https://open.wenmarpro.com/bulletins/11036405), 2026-08-27: Service Bulletin \- Under certain conditions, the cylinder head gasket effectiveness may be reduced which may cause vehicles to experience overheating, coolant loss, misfire and/or DTCs P0300 thru P0304 stored.
- [11036336](https://open.wenmarpro.com/bulletins/11036336), 2026-08-24: Service Bulletin \- Under certain conditions, the cylinder head gasket effectiveness may be reduced which may cause vehicles to experience overheating, coolant loss, misfire and/or DTCs P0300 thru P0304 stored.
- [10233208](https://open.wenmarpro.com/bulletins/10233208), 2023-03-23: Service Bulletin \- Under certain circumstances, the vehicle may experience driveability concerns. This may result in the following DTC’s to set: • P0300 \(Random Misfire Detected\), • P0301 \(No. 1 Cylinder Misfire Detected\), • P0302 \(No. 2 Cylinder Misfire Detected\), • P0303 \(No. 3 Cylinder Misfire Detected\), • P0304 \(No. 4 Cylinder Misfire Detected\), • P0172 \(Fuel System Too Rich\)