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What P0302 means for your Honda Civic
Your Civic's ECM detected that cylinder 2 isn't firing properly - the crankshaft position sensor saw the rotational speed dip slightly each time cylinder 2 was supposed to combust. On the 1.5L turbo Civic (2016-2021), P0302 is almost always fuel dilution from cold-climate short-trip driving causing cyl-2 to misfire. On the 2.0L K20 and 1.8L R18, it's typically a coil or plug at 100k+.
🎯 Top Causes on the Honda Civic
55%
#1 CAUSE
Fuel-Dilution Misfire (1.5T L15B7)
The 2016-2021 Civic 1.5T has a well-documented fuel-in-oil problem: in cold weather and short trips, unburned gasoline washes past the rings into the crankcase, thinning the oil and raising oil level. The thinned oil cannot maintain ring seal and cylinder 2 (the longest fuel run) tends to develop a soft compression loss + misfire. Honda issued a service campaign (16-110) updating the ECM and PCV. Check the oil dipstick - if it smells like gasoline or is overfilled, you have fuel dilution. Long highway drives temporarily clear it; an oil change with full synthetic 0W-20 plus a software update is the real fix.
Oil Change
$60-$90
Software Update
$0 (warranty)
Ring Job (worst case)
$2500-$4500
25%
#2 CAUSE
Cylinder 2 Ignition Coil Failure
On the naturally-aspirated R18 (1.8L) and K20 (2.0L) Civic, the OEM Hitachi coils begin failing between 90k and 140k miles. The cyl-2 coil sits between cyls 1 and 3 in the rail and runs hot. Swap cyl-2 with cyl-4: if misfire follows to cyl 4, replace the coil. NGK U5167 is a reliable OE-equivalent for around $50.
OEM Coil
$80-$130
Aftermarket
$45-$70
w/Labor
$120-$260
20%
#3 CAUSE
Worn or Fouled Spark Plug
Civic plugs (NGK IZFR6K-11S on R18, ILZKAR7B11 on 1.5T) are spec'd for 100k miles but the 1.5T fouls plugs much sooner - often by 60k - because of fuel dilution and direct-injection deposits. Pull the cyl-2 plug and inspect. The 1.5T plugs require special handling: do not over-torque (13 ft-lbs) and never reuse a removed plug.
Plugs (set 4)
$35-$70
1.5T Plugs
$60-$100
w/Labor
$80-$220
🚗 Most Affected Civic Model Years
| Year | Engine | Primary Cause | Typical Mileage | Notes |
|---|---|---|---|---|
| 2016-2021 | 1.5L L15B7 Turbo | Fuel dilution | 30k-90k | Cold-climate short-trip cars worst |
| 2006-2011 | 1.8L R18A | Coil + plug | 100k-160k | Very reliable, fails late |
| 2012-2015 | 1.8L R18Z | Coil | 90k-140k | Same engine family |
| 2017-2021 | 2.0L K20C2 (Si/Sport) | Coil or plug | 70k-120k | Less common than 1.5T issues |
🔧 How to Diagnose P0302 on a Honda Civic
- Check the oil level and smell on a 1.5T. If oil is above the upper hash mark or smells like gasoline, you have fuel dilution. Take it to a Honda dealer - software updates and a TSB extended-warranty are available for many VINs.
- Swap cyl-2 coil with cyl-4 on any Civic generation. If the misfire follows the coil to cyl 4 (P0304), the coil is the problem. Honda coils take a 8mm or 10mm bolt depending on year.
- Inspect the cyl-2 spark plug condition. For 1.5T, also check for direct-injection carbon buildup on the intake valves with a borescope - the 1.5T has port + direct injection but the DI side coats the back of the valves over time.
Want a step-by-step walkthrough specific to your Honda Civic? Run a $5.99 AI diagnosis report - we narrow the cause to your year, engine, and symptoms.
❓ Frequently Asked Questions
Is P0302 on a 1.5T Civic covered under warranty?
If your VIN is included in Honda's 1.5T Service Bulletin 18-114 / 19-115 (oil dilution campaign), Honda will perform an ECM update and provide an extended powertrain warranty - often 8 years/100k miles - for fuel-dilution-related misfires. Bring it to the dealer with the P0302 code documented.
Is the 1.5T Civic fuel dilution problem dangerous?
It can be. Thinned oil loses film strength and accelerates bearing wear. In cold climates with short trips, owners report rod-bearing failures by 80k miles. If you see oil level rising, fix it now - don't just keep driving.
How much does it cost to fix P0302 on a Civic?
On non-turbo Civics: $120-$260 for a coil or plug job. On a 1.5T with fuel dilution: $0 if covered by the TSB warranty, or $90 for an oil change + software check at an independent shop. Ring-job worst case (rare): $3000+.
Which cylinder is cylinder 2 on a Honda Civic?
Honda numbers from the timing-belt/chain side. On the inline-4 Civic engines (R18, K20, L15B), cyl 1 is at the passenger side of the engine bay (right end as you face the car) and cyl 2 is next to it. Cyl 4 is at the transmission side.
Can a clogged PCV valve cause P0302 on a 1.5T?
Yes. A failed PCV traps blow-by in the crankcase and worsens fuel dilution. The 1.5T PCV is part of Honda's service update - replace it whenever you update the ECM. About $40 in parts.
See all P0302 causes (all vehicles) → · Related: Honda 1.5T Fuel Dilution →