P0304 Honda Hr-V
Cylinder 4 Misfire Detected · Powertrain Code · High · Repair: Moderate
What is P0304?
Misfire detected in cylinder 4. Typically caused by a worn spark plug, bad ignition coil, faulty fuel injector, or low compression in that cylinder.
When the Honda Hr-V triggers code P0304 (cylinder 4 misfire detected), it typically points to an issue in the powertrain system. This is a high severity code, so address it promptly to avoid further damage or safety concerns. Below you'll find the most common causes, symptoms, and repair options specific to the Honda Hr-V.
This repair is rated moderate, meaning some experience and specialty tools required.
Diagnostic data on this page is compiled from publicly available repair resources and technical service bulletins. Always have a qualified mechanic confirm the diagnosis before authorizing repairs on your Honda Hr-V.
Common Causes on Honda Hr-V
- Worn spark plug on cylinder 4
- Faulty ignition coil on cylinder 4
- Carbon buildup on intake valves (Earth Dreams DI engines)
- Low compression from worn piston rings or valve seats
- Vacuum leak at cylinder 4 intake runner
Symptoms
- Flashing CEL during active misfire
- Rough idle with engine vibration
- Noticeable loss of power
- Poor acceleration
- Uneven exhaust note
Notes for Honda Hr-V
If misfires appear on multiple cylinders over time, suspect carbon buildup on DI engines rather than individual coil failures.