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 communications
12Original wording in English
HONDA
Reported code forms P0303
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 P0303
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 P0303
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 P0303
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 P0303
"Service bulletin - American Honda is announcing a powertrain warranty extension 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.…
HONDA
Reported code forms P0303
"Service bulletin - American Honda is announcing a powertrain warranty extension 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
7A 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.