P0308 on Honda: How to Diagnose & Fix
Cylinder 8 Misfire Detected
1 Honda model · 2 documented issues · $80-$400 repair
P0308 on Honda by model: symptoms, diagnosis and fix
Original equipment spark plugs fail prematurely across all Honda Fit generations, sometimes before 30,000 miles. Original iridium plugs don't hold up well in the L15A/L15B engines. FitFreak forum consensus: replace every 20,000-25,000 miles instead of Honda's recommended 30,000 miles. NGK Laser Platinum plugs are the consensus #1 choice among Fit owners. Improper spark plug gap or torque causes premature failure.
Common Symptoms
- Rough idle
- Hesitation during acceleration
- Engine misfire codes P0300-P0308
- Check engine light illuminated
- Reduced fuel economy
- Hard starting when cold
How to Fix
Replace spark plugs every 20,000-25,000 miles instead of 30,000. Use NGK Laser Platinum ($22-30 per plug) or Denso Iridium Long Life ($24-32 per plug). Ensure proper gap (0.043 inches) and torque specification. DIY replacement very accessible on Fit (engine bay open). Torque wrench CRITICAL - improper torque causes premature failure.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Genuine Honda 12290-RB1-003 NGK IZFR6K13 iridium spark plugOEMHonda 12290-RB1-003 / NGK IZFR6K13
Required quantity four; do not mix plug families.
- Genuine Honda 12290-5R0-003 NGK DILZKAR7C11S iridium spark plugOEMHonda 12290-5R0-003 / NGK DILZKAR7C11S
Required quantity four; preset gap and do not mix plug families.
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Owner tips & cautions
- WarningUse torque wrench for installation - improper torque is #1 cause of premature spark plug failure in Fits
- TipReplace every 20k-25k miles instead of Honda's 30k recommendation - prevents misfires and saves money
- TipDIY replacement is very easy on Fits - engine bay accessible, saves $150-250 in shop labor
Sources for this issue (2)
Ignition coil packs can fail causing engine misfires. Usually one coil fails at a time. Engine misfire, rough idle, check engine light with misfire codes. Bosch ($50-80 each) or Denso ($60-90 each) replacement coils recommended on FitFreak. Replace all four at once ($200-300) to prevent future failures and repeated labor costs. DIY installation very easy (bolt on, connector plug) - saves $100-200 in shop labor.
Common Symptoms
- Engine misfire
- Rough idle
- Check engine light with misfire codes P0300-P0308
- Reduced fuel economy
- Hesitation during acceleration
How to Fix
Test coil pack resistance with multimeter before replacing to confirm failure. Replace failed ignition coil pack. Consider replacing all four if one fails (preventive measure, $200-300 for all four). Bosch ($50-80 each) or Denso ($60-90 each) recommended. DIY installation very easy.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Genuine Honda 30520-PWC-S01 ignition coilOEMHonda 30520-PWC-S01
First-generation replacement after diagnosis identifies a failed coil Fitment/availability: 2007-2008 U.S. Honda Fit Base and Sport, 5MT or 5AT; one coil per cylinder.
- Genuine Honda 30520-RB0-S01 ignition coilOEMHonda 30520-RB0-S01
Second-generation replacement after diagnosis identifies a failed coil Fitment/availability: 2009-2013 U.S. Honda Fit Base/Fit and Sport, 5MT or 5AT; one coil per cylinder.
- Genuine Honda 30520-5R0-013 ignition coilOEMHonda 30520-5R0-013
Third-generation replacement after diagnosis identifies a failed coil Fitment/availability: 2015-2020 U.S. Honda Fit, all cataloged trims, 6MT or CVT; one coil per cylinder.
As an Amazon Associate, we earn from qualifying purchases; other part links may also earn au7o a commission. Confirm fitment by VIN before buying.
Owner tips & cautions
- TipReplace all four at once ($200-300) to prevent future failures and repeated labor costs
- TipDIY installation is very easy - bolt on, connector plug - saves $100-200 in shop labor
- WarningAvoid knockoff coils on eBay/Amazon - they fail quickly and waste money
Sources for this issue (2)
P0308 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0308 mean on a Honda?
P0308 stands for "Cylinder 8 Misfire Detected." P0308 means the engine computer detected a misfire on cylinder number 8 — that cylinder is failing to combust properly or at the correct time. The PCM identifies it by monitoring crankshaft speed variations as cylinder 8 fires. Misfires waste fuel, increase emissions, and can overheat and damage the catalytic converter, so a hard misfire may cause a flashing check engine light. Typical symptoms include rough idle, vibration, hesitation, and reduced power. On Honda it is documented across 1 model: Fit.
What are the most common causes of P0308?
The most common causes of P0308 are: Worn, fouled, or incorrectly gapped spark plug on cylinder 8, Failed ignition coil or coil-on-plug for cylinder 8, Faulty, clogged, or leaking fuel injector, Vacuum or intake air leak affecting that cylinder, Low compression (worn rings, burnt/leaking valve, head gasket), Damaged spark plug wire or boot (on applicable engines), Carbon buildup or sticking valve. The specific cause varies by vehicle.
How much does it cost to fix P0308 on a Honda?
Published repair estimates on Honda range from $80 to $400 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
Looking for P0308 on a different make?
View P0308 across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.