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.
P0304Random/Multiple Cylinder Misfire DetectedManufacturer communications
5Original wording in English
TOYOTA
Reported code forms P0304
TSB: Some 2013 ? 2015 Prius PHV, Prius and 2013 ? 2016 Prius V vehicles may exhibit a vibration due to rough idle and/or tapping noise from the HV transaxle at cold start. The check engine light may also illuminate with…
TOYOTA
Reported code forms P0304
TSB: REVISION NOTICE August 11, 2016 Rev1: Applicability has been updated to include 2016 model year Prius V vehicles. Any previous printed versions of this bulletin should be discarded. Some 2010 - 2015 model year…
TOYOTA
Reported code forms P0304
TSB: REVISION NOTICE AUGUST 11, 2016 REV1: APPLICABILITY HAS BEEN UPDATED TO INCLUDE 2016 MODEL YEAR PRIUS V VEHICLES. ANY PREVIOUS PRINTED VERSIONS OF THIS BULLETIN SHOULD BE DISCARDED. SOME 2010 – 2015 MODEL YEAR…
TOYOTA
Reported code forms P0304
Tech Tip: Some customers may experience a Knocking sound and/or Runs Rough on engine start following a cold soak. This may or may not occur with DTC(s) P0300, P0301, P0302, P0303 and / or P0304.
TOYOTA
Reported code forms P0304
M.I.L. ON DTC P0300, P0301, P0302, P0303, OR P0304. *TT
Check vehicle applicability
9A 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.