P0304
171 owner reports and 756 manufacturer filings across 278 model years from Acura, Alfa Romeo, Audi, Chevrolet and others.
Where P0304 shows up
Source: NHTSA manufacturer communications and complaintsShowing the 60 model years where P0304 appears most; it is on file for 278 in total.
A model year appears here because the code is named in its record, not because every one of these vehicles sets it. Counts are mentions in the federal files, not failure rates — nobody publishes the denominator.
What it gets filed under
When owners report it
miles, typically
Half of the 31 owner reports naming P0304 that carry an odometer reading fall between 56,000 and 87,000 miles. A code that shows up at 30,000 miles is a different proposition from one that shows up at 130,000, and that difference is the single most useful thing in this record.
What owners said
Source: NHTSA complaint databaseOwners’ own words, one per nameplate, scrubbed of anything identifying. These are unverified reports filed with NHTSA — they are what was said, not a finding that it was true.
This time, as soon as we got home, we used an engine code reader and saw code P0304 – Cylinder 4 misfire
The contact followed the instructions, and the contact's brother retrieved DTC: P0304, indicating a cylinder 4 misfire
The problem was confirmed by a certified technician who pulled active diagnostic trouble codes P0304 and P0316
We bought a used car from Carvana and had a check engine light come on in the first month for P0304- cylinder 4 misfire
· Active Diagnostic Trouble Codes (DTCs) stored: P0017, P0014, P000B, P0172, P0300, P0301, P0302, P0303, P0304
Manufacturer filings that name it
Source: NHTSA manufacturer communicationsService bulletins and campaigns whose filed summary names P0304. Quoting the document number at a service desk is often the fastest route to a diagnosis someone has already written down.
- AEBM08262026901 Other2026-08-26 · Engine
- 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.
- B26-0032026-08-26 · Engine
- 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.
- B26-0022026-08-26 · Engine
- 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.
- B26-0012026-08-26 · Engine
- 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.
- BEBM08262026901 Other2026-08-26 · Engine
- 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.
- A26-0192026-08-26 · Engine
- 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.
What P0304 means
Source: SAE J2012 / OBD-IICylinder 4 is misfiring.
A stored code names the test that failed, never the part that caused it. It is the starting point of a diagnosis, not its conclusion — the same code has several possible causes and the cheap one is not always right.
Common questions about P0304
Source: NHTSA files and the OBD-II standardCan I keep driving with P0304 stored?
Nobody can answer that from the code alone, and a site that does is guessing. A steady light generally means the fault was logged and the vehicle is in a reduced-risk mode; a flashing light means stop soon, because a misfiring engine can destroy a catalytic converter in minutes. The safe read of this page is the mileage and the components, not permission.
Does a code mean the car is recalled?
No. Recalls are filed by campaign and matched by VIN, and none of them are triggered by a scan tool. If you want to know whether an open recall applies to one specific vehicle, check the VIN at nhtsa.gov/recalls — that is the only source that settles it.
Why do the counts here differ from other sites?
Because these are not estimates. Every number on this page is a count of documents in NHTSA's own files: manufacturer communications that name the code in their filed summary, and owner complaints that name it in the narrative. We do not model, weight or extrapolate them.
Will clearing the code fix it?
Clearing turns the light off and erases the freeze-frame data a technician would have used to work out what happened. If the condition is still there the code returns, usually within a few drive cycles, and the diagnosis now starts from less information than before.