{"vehicle":{"id":"2018_honda_civic","year":2018,"make":"Honda","model":"Civic"},"code":"P0304","generic":true,"description":null,"bulletins":{"as_of":"2026-10-19","count":23,"bulletins":[{"nhtsa_id":11037695,"type":"service_bulletin","type_name":"Service bulletin","date_added":"2026-10-01","date":"2026-09-25","document_id":"A26-009","mfr_campaign":null,"component":"ENGINE","summary":"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).","document":{"url":"https://static.nhtsa.gov/odi/tsbs/2026/MC-11037695-0001.pdf","alternate_url":"https://static.nhtsa.gov/odi/tsbs/2026/MC-11037695-9999.pdf","confirmed":false},"url":"https://open.wenmarpro.com/bulletins/11037695"},{"nhtsa_id":11037693,"type":"service_bulletin","type_name":"Service bulletin","date_added":"2026-10-01","date":"2026-09-25","document_id":"A26-008","mfr_campaign":null,"component":"ENGINE","summary":"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).","document":{"url":"https://static.nhtsa.gov/odi/tsbs/2026/MC-11037693-0001.pdf","alternate_url":"https://static.nhtsa.gov/odi/tsbs/2026/MC-11037693-9999.pdf","confirmed":false},"url":"https://open.wenmarpro.com/bulletins/11037693"},{"nhtsa_id":11036424,"type":"other","type_name":"Other","date_added":"2026-08-27","date":"2026-08-26","document_id":"AEBM08262026901","mfr_campaign":null,"component":"ENGINE","summary":"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.","document":{"url":"https://static.nhtsa.gov/odi/tsbs/2026/MC-11036424-0001.pdf","alternate_url":"https://static.nhtsa.gov/odi/tsbs/2026/MC-11036424-9999.pdf","confirmed":false},"url":"https://open.wenmarpro.com/bulletins/11036424"},{"nhtsa_id":11036408,"type":"service_bulletin","type_name":"Service bulletin","date_added":"2026-08-27","date":"2026-08-26","document_id":"A26-009","mfr_campaign":null,"component":"ENGINE","summary":"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.","document":{"url":"https://static.nhtsa.gov/odi/tsbs/2026/MC-11036408-0001.pdf","alternate_url":"https://static.nhtsa.gov/odi/tsbs/2026/MC-11036408-9999.pdf","confirmed":false},"url":"https://open.wenmarpro.com/bulletins/11036408"},{"nhtsa_id":11036407,"type":"service_bulletin","type_name":"Service bulletin","date_added":"2026-08-27","date":"2026-08-26","document_id":"A26-008","mfr_campaign":null,"component":"ENGINE","summary":"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.","document":{"url":"https://static.nhtsa.gov/odi/tsbs/2026/MC-11036407-0001.pdf","alternate_url":"https://static.nhtsa.gov/odi/tsbs/2026/MC-11036407-9999.pdf","confirmed":false},"url":"https://open.wenmarpro.com/bulletins/11036407"},{"nhtsa_id":10230496,"type":"service_bulletin","type_name":"Service bulletin","date_added":"2023-01-20","date":"2023-01-11","document_id":"A19-033","mfr_campaign":null,"component":"ENGINE AND ENGINE COOLING","summary":"Service Bulletin - Under certain circumstances, the vehicle may experience driveability issues, which may result in DTCs 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), or P0172 (fuel system too rich) or a whirling noise coming from the engine compartment.","document":{"url":"https://static.nhtsa.gov/odi/tsbs/2023/MC-10230496-0001.pdf","alternate_url":"https://static.nhtsa.gov/odi/tsbs/2023/MC-10230496-9999.pdf","confirmed":false},"url":"https://open.wenmarpro.com/bulletins/10230496"},{"nhtsa_id":10230495,"type":"service_bulletin","type_name":"Service bulletin","date_added":"2023-01-20","date":"2023-01-11","document_id":"A19-012","mfr_campaign":null,"component":"ENGINE AND ENGINE COOLING; VISIBILITY","summary":"Service Bulletin - This bulletin is replaced by S/B 19-033, Warranty Extension: 2016-18 Civic 1.5L: Software Update with A/C Control Unit Replacement; DTC P0300, P0301, P0302, P0303, P0304, or P0172; Whirling Noise from Engine.","document":{"url":"https://static.nhtsa.gov/odi/tsbs/2023/MC-10230495-0001.pdf","alternate_url":"https://static.nhtsa.gov/odi/tsbs/2023/MC-10230495-9999.pdf","confirmed":false},"url":"https://open.wenmarpro.com/bulletins/10230495"},{"nhtsa_id":10165769,"type":"service_bulletin","type_name":"Service bulletin","date_added":"2019-10-09","date":"2019-10-02","document_id":"A19-038","mfr_campaign":null,"component":"ENGINE AND ENGINE COOLING","summary":"Service Bulletin - Under certain circumstances, the vehicle may experience driveability issues, which may result in DTCs 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), or P0172 (fuel system too rich) or a whirling noise coming from the engine compartment.","document":{"url":"https://static.nhtsa.gov/odi/tsbs/2019/MC-10165769-0001.pdf","alternate_url":"https://static.nhtsa.gov/odi/tsbs/2019/MC-10165769-9999.pdf","confirmed":false},"url":"https://open.wenmarpro.com/bulletins/10165769"},{"nhtsa_id":10163173,"type":"service_bulletin","type_name":"Service bulletin","date_added":"2019-07-23","date":"2019-07-08","document_id":"ONLE4C07082019","mfr_campaign":null,"component":"ENGINE AND ENGINE COOLING","summary":"Owner Notification Letter - Some 2016-18 Civic vehicles equipped with the 1.5 liter turbocharged engine may experience driveability issues. This may result in Diagnostic Trouble Codes (DTCs) 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), or P0172 (fuel system too rich) or a whirling noise coming from the engine compartment. These concerns may result in the Malfunction Indicator Lamp (MIL) turning on.","document":{"url":"https://static.nhtsa.gov/odi/tsbs/2019/MC-10163173-0001.pdf","alternate_url":"https://static.nhtsa.gov/odi/tsbs/2019/MC-10163173-9999.pdf","confirmed":false},"url":"https://open.wenmarpro.com/bulletins/10163173"},{"nhtsa_id":10163172,"type":"service_bulletin","type_name":"Service bulletin","date_added":"2019-07-23","date":"2019-07-08","document_id":"ONLD4D07082019_2","mfr_campaign":null,"component":"ENGINE AND ENGINE COOLING","summary":"Owner Notification Letter - Some 2016-18 Civic vehicles equipped with the 1.5 liter turbocharged engine may experience driveability issues. This may result in Diagnostic Trouble Codes (DTCs) 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), or P0172 (fuel system too rich) or a whirling noise coming from the engine compartment. These concerns may result in the Malfunction Indicator Lamp (MIL) turning on.","document":{"url":"https://static.nhtsa.gov/odi/tsbs/2019/MC-10163172-0001.pdf","alternate_url":"https://static.nhtsa.gov/odi/tsbs/2019/MC-10163172-9999.pdf","confirmed":false},"url":"https://open.wenmarpro.com/bulletins/10163172"}],"url":"https://open.wenmarpro.com/makes/honda/civic/2018/bulletins?code=P0304"},"related":{"components":[],"bulletins":[],"recalls":{"may_apply":true,"recalls":[],"lookup":{"nhtsa":"https://www.nhtsa.gov/recalls","tc":"https://wwwapps.tc.gc.ca/Saf-Sec-Sur/7/VRDB-BDRV/search-recherche/menu.aspx?lang=eng","maker":null}}},"url":"https://open.wenmarpro.com/makes/honda/civic/2018/codes/P0304","note":"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.","attribution":["Contains information licensed under the Open Government Licence – Canada."]}