What does this code mean?
P0300 indicates random or multiple-cylinder misfire. P0301–P0308 identify the numbered cylinder. Ignition, fuel delivery, compression, air leaks or mechanical timing can cause misfire. Use misfire counters, freeze-frame data and appropriate tests to narrow the cause. A flashing malfunction light can signal a misfire that may damage the catalyst.
Sources and interpretation [1]
A code identifies a detected condition, not a part that must automatically be replaced.
Manufacturer wording
Source wording can vary by vehicle and suffix. It is shown as written, not as a universal diagnosis.
P0304Number 1-4 cylinder misfire detectedManufacturer communications
30Original wording in English
HONDA
Reported code forms P0304
Service Bulletin - The piston ring function deteriorates due to ring low wear toughness and sticking from sludge. Oil adheres to the spark plug leading to carbon fouling and misfire. This can set DTCs P0301 No. 1…
HONDA
Reported code forms P0304
Service Bulletin - The piston ring function deteriorates due to ring low wear toughness and sticking from sludge. Oil adheres to the spark plug leading to carbon fouling and misfire. This can set DTCs P0301 No. 1…
HONDA
Reported code forms P0304
Owner Notification Letter - the piston ring function can deteriorate due to ring low wear toughness and sticking from sludge. Oil adheres to the spark plug leading to carbon fouling and misfire. This can set DTCs P0301…
HONDA
Reported code forms P0304
Service Bulletin - The piston ring function deteriorates due to ring wear and sticking from sludge. Oil from the crankcase adheres to the spark plug leading to carbon fouling and misfire. This can set DTCs P0301 No. 1…
HONDA
Reported code forms P0304
Dealer Message - Piston ring effectiveness may be reduced due to excessive wear and oil sludge build-up, which can cause oil to adhere to the spark plug, potentially leading to carbon fouling and misfire triggering DTCs…
HONDA
Reported code forms P0304
Service Bulletin - American Honda announced a powertrain warranty extension in 2013 as a result of a settlement of a class action captioned, Soto et al.v. American Honda Motor Co., Inc., Case No. 3:12-cv-1377-SI (N.D.…
Check vehicle applicability
10A listed vehicle is a research lead. Confirm the engine, production range and software in the manufacturer's information.
Before replacing a part
Record codes and freeze-frame data. Check battery condition, related codes and visible wiring or hose damage. Follow the vehicle's diagnostic procedure and test results before replacing parts.
Sources and interpretation
These explanations are editorial summaries of the linked manufacturer material. PDF page numbers count from the first file page. Original publications are in English; translations are reference aids. A cited edition is not a claim that it is the manufacturer's latest instruction.
- 01 13 14 / 2033805 · Engine, Misfire Diagnostic Aid ↗
Volkswagen Group of America · PDF page(s) 1, 2 ·
- 2024–2025 MY OBD System Operation Summary for Gasoline Engines ↗
Ford Motor Company · PDF page(s) 9, 10 ·
Source check date · 2026-10-27
Can I keep driving?
A code alone cannot establish whether driving is safe. A flashing malfunction light, severe shaking, overheating, oil-pressure warning or loss of braking or steering needs prompt attention. Stop in a safe place and seek assistance when control or engine safety is affected. Follow the vehicle handbook.