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
3Original wording in English
SUBARU
Reported code forms P0300
This bulletin announces the availability of new reprogramming files for optimizing the ECM to address the following customer concern: ? Rough idle after a warm engine restart. In rare cases, DTC P0300 may also be stored.
SUBARU
Reported code forms P0300
"THIS BULLETIN ANNOUNCES THE AVAILABILITY OF NEW REPROGRAMMING FILES FOR OPTIMIZING THE ECM TO ADDRESS THE FOLLOWING CUSTOMER CONCERN: • ROUGH IDLE AFTER A WARM ENGINE RESTART. IN RARE CASES, DTC P0300 MAY ALSO BE…
SUBARU
Reported code forms P0300
"THIS SERVICE INFORMATION BULLETIN REVIEWS A DESIGN CHANGE TO THE ENGINE WIRING HARNESS TO ELIMINATE IMPROPER DIAGNOSIS OF THE EVAPORATIVE LEAK CHECK MODULE (ELCM) BY THE ECM WHICH COULD SET DIAGNOSTIC TROUBLE CODE…
Check vehicle applicability
4A 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.