What does code P0300 mean on a Honda and is it safe to drive?
P0300: Random/Multiple Cylinder Misfire Detected. Here's what it means on your Honda, what usually causes it, what repairs typically cost, and how safe it is to keep driving.
What this code means
The PCM has detected misfires across multiple cylinders. This can cause damage to the catalytic converter if driven for long.
Common causes for your Honda
- Worn spark plugs or ignition coils
- Clogged or bad fuel injectors
- Low compression
- Vacuum leak, bad MAF, or fuel delivery issue
Symptoms
- Check Engine Light (often flashing under load)
- Rough idle, shaking, loss of power
- Possible smell of unburned fuel
Typical fixes
- Replace spark plugs and coils as needed
- Clean or replace fuel injectors
- Fix vacuum/fuel issues
- Compression test if no obvious cause
Repair cost range
For a Honda, repairs for P0300 often fall between $150 and $1200, depending on the cause and whether you use OEM or aftermarket parts. Labor rates vary by location.
Known issues on Honda
Honda P0300 on K24 and R18 engines is frequently caused by a melted or corroded ignition coil harness connector—the coil connector on cylinder 1–4 can melt from exhaust heat proximity. Inspect all four connectors before buying parts. On Accord V6 3.5L J35, the rear three coils (cylinders 4–6) are difficult to access and are often skipped during tune-ups, leading to ignition failure. Honda spark plugs should be replaced at 30k–60k intervals; extended plug intervals cause electrode erosion and P0300.
Most commonly affected models