# P0300 on the 2021 Honda Civic

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 P0300

- [11037695](https://open.wenmarpro.com/bulletins/11037695), 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 \(DTCs are not required for repair\).
- [11037693](https://open.wenmarpro.com/bulletins/11037693), 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.
- [11036408](https://open.wenmarpro.com/bulletins/11036408), 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.
- [11036407](https://open.wenmarpro.com/bulletins/11036407), 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.