P0302 Code: Honda Civic (2022-2024) - Causes, Symptoms & Fixes

No recalls found in NHTSA database for 2022-2024 Honda Civic with code P0302.

In the provided data, there are no NHTSA owner complaints specifically for P0302 on this model/year, so the statistics shown reflect zero complaints in that dataset. This does not guarantee the absence of P0302 occurrences in the real world, just that the dataset here doesn't show complaints or recalls for this exact combination.

CODE MEANING AND SEVERITY

• What P0302 means: P0302 is a misfire diagnostic trouble code indicating cylinder 2 is not firing as it should. The engine control module (ECM/PCM) detects the cylinder 2 misfire based on irregular combustion, RPM fluctuations, or abnormal ignition/fuel data.
• Severity and implications:
  • Occasional, mild misfires may cause rough idle or light hesitation but might be tolerated for a short period.
  • Repeated or severe misfires can cause rough running, noticeable loss of power, and increased emissions. A flashing Check Engine Light typically indicates a severe misfire that could damage the catalytic converter if driven for long.
  • Prolonged misfire on cylinder 2 increases the risk of overheating the catalytic converter and can lead to more expensive repairs if not addressed promptly.

COMMON CAUSES ON HONDA CIVIC (2022-2024)

Note: P0302 applies to cylinder 2 on four-cylinder engines used in these Civics (engine families include 1.5L turbo and 2.0L naturally aspirated variants). Typical root causes include:

• Ignition system
  • Faulty or worn spark plug on cylinder 2 (fouled, oil-contaminated, or improper gap)
  • Faulty ignition coil on cylinder 2 or a degraded coil pack/wiring to the coil
  • Damaged or loose ignition coil boot or wiring harness connector
• Fuel system
  • Clogged or leaking fuel injector for cylinder 2
  • Low fuel pressure or inaccurate injector pulse to cylinder 2
• Air and intake system
  • Vacuum leak near cylinder 2 (intake manifold gasket, vacuum hoses)
  • Mass Air Flow (MAF) sensor or intake cleanliness issues affecting cylinder-specific fuel delivery
• Engine mechanical
  • Compression issues in cylinder 2 (valve seating, piston rings, head gasket leaks)
• Electrical/software
  • Wiring harness corrosion or bad ground to cylinder 2 coil/injector
  • ECM/PCM sensor data misinterpretation (less common; often paired with another DTC)

Note: Direct-injection engines, and typical modern Civics, can accumulate carbon buildup on intake valves over time, which may contribute to misfires or drivability symptoms if not addressed.

SYMPTOMS

• Rough idle or trembling at idle
• Hesitation, stumbling, or loss of power during acceleration
• Reduced fuel economy
• Engine may feel unstable or vibrate, especially at idle
• Check Engine Light (solid) or flashing if misfire is severe
• Possible slight exhaust smell of unburnt fuel if the misfire is persistent

DIAGNOSTIC STEPS

A careful, systematic approach targets cylinder 2 first, then general misfire checks.

• Step 0: Confirm the DTC and data

  • Read the code with a scan tool and note freeze-frame data: RPM at misfire, engine load, coolant temperature, fuel trims, and misfire counters.
  • Confirm the fault is specifically P0302 (cylinder 2 misfire) and check for related codes (P0300 for random/multiple misfires, or P0352 for ignition coil 2 if a coil-related code appears).

• Step 1: Basic physical inspection

  • Inspect spark plug on cylinder 2: condition, gap, fouling, oil/fuel contamination.
  • Inspect ignition coil/connectors for cylinder 2: corrosion, cracks, or loose connections.
  • Check associated wiring harnesses and connectors to coil and injector for damage or looseness.
  • Look for obvious vacuum leaks near cylinder 2 (intake manifold gaskets, hoses, PCV valve position).

• Step 2: Swap test (determine if the misfire is coil/plug or cylinder-specific)

  • Swap the spark plug from cylinder 2 with another cylinder (e.g., cylinder 1). Clear codes and run engine; if the misfire moves to the new cylinder, the plug is likely at fault. If it stays on cylinder 2, the coil, injector, or cylinder-specific issue is more likely.
  • Alternatively, swap the ignition coil (or coil pack) from cylinder 2 with a neighboring cylinder. If the misfire follows the coil, the coil is faulty; if the misfire remains on cylinder 2, the coil is likely not the issue.

• Step 3: Check ignition spark and coil output

  • With a scope or a known-good spark tester, verify there is a strong, consistent spark on cylinder 2 when the engine is cranking.
  • Inspect coil resistance values (if specified by Honda service data) and compare to spec.

• Step 4: Inspect/clean fuel injector for cylinder 2

  • Listen for injector operation on cylinder 2 with a mechanic’s stethoscope. If no click is heard, injector may be stuck or not pulsing.
  • Check injector coil resistance and compare to specification.
  • Consider a temporary injector cleaning additive if appropriate, but be aware it may not resolve a mechanically stuck injector.

• Step 5: Check compression and mechanical condition

  • Perform a compression test or a cylinder leak-down test on cylinder 2 to assess mechanical health.
  • Low compression in cylinder 2 could indicate valve sealing issues, piston ring wear, or head gasket problems.

• Step 6: Scan for related sensors and data

  • Check MAF sensor readings, fuel trims (LTFT/STFT). Abnormally high or fluctuating trims near idle or at a given RPM can indicate fueling or air-induction issues affecting cylinder 2.
  • Inspect for EVAP or other secondary systems that could influence engine performance, though these are less likely to produce a cylinder-precise misfire.

• Step 7: If no obvious cause found

  • Re-check all connectors and grounds to cylinder 2 components (coil, injector, spark plug region).
  • Consider performing a professional fuel injector cleaning or a more in-depth engine mechanical inspection if compression tests fail to identify issues.

• Step 8: Post-repair validation

  • Clear codes, start the engine, and perform a road test.
  • Monitor for reoccurrence of P0302 and monitor ignition/fuel-related data to ensure the issue is resolved.

RELATED CODES

• P0300: Random/Multiple Cylinder Misfire Detected (may indicate a system-wide issue or multiple misfires)
• P0301, P0303, P0304: Misfire in cylinder 1, 3, or 4 respectively
• P0351, P0352, P0353, P0354: Ignition coil circuit problems for cylinders 1–4 (if the issue is coil-related, you may see P0352 specifically for cylinder 2)
• P0302 may occur alongside fuel delivery or ignition circuit faults; a thorough check of the ignition coil and injector circuits is common when diagnosing P0302.

REPAIR OPTIONS AND COSTS (2025 PRICES)

Prices vary by region, shop type (dealer vs independent), and labor rates. The following are rough ranges for the United States as of 2025. All estimates assume typical OEM or equivalent quality parts.

• Spark plug replacement (cylinder 2)

  • Parts: $5–$25
  • Labor: 0.5–1.0 hours
  • Typical total: $60–$200
  • Notes: If you’re replacing all four plugs, total parts: ~$20–$80; labor roughly 2–3 hours, total $200–$500 depending on rate.

• Ignition coil replacement (cylinder 2)

  • Parts: $60–$140
  • Labor: 0.3–0.7 hours
  • Typical total: $100–$250

• Spark plug + ignition coil (cylinder 2)

  • Parts: $65–$165
  • Labor: 0.6–1.2 hours
  • Typical total: $150–$350

• Fuel injector (cylinder 2) – cleaning

  • Parts: minimal (cleaning solution), negligible if cleaning covers
  • Labor: 0.5–1.0 hours
  • Typical total: $60–$140

• Fuel injector (cylinder 2) – replacement

  • Parts: $80–$320 (OEM higher end; aftermarket may be cheaper)
  • Labor: 0.5–1.0 hours
  • Typical total: $150–$500

• Fuel system cleaning or additive (temporary measure)

  • Parts: $5–$20 for additive
  • Labor: minimal
  • Typical total: $10–$50

• Vacuum leak repair near cylinder 2 (gaskets, hoses)

  • Parts: $20–$200 (gaskets, hoses)
  • Labor: 0.5–1.5 hours
  • Typical total: $120–$400

• Intake or MAF sensor cleaning/replacement

  • Cleaning
    • Parts: $0–$20 for cleaner
    • Labor: 0.1–0.3 hours
    • Typical total: $20–$60
  • Replacement
    • Parts: $120–$350
    • Labor: 0.3–0.7 hours
    • Typical total: $180–$520

• Compression test / cylinder leak-down test

  • Parts: minimal
  • Labor: 0.5–1.5 hours if performed as part of repair
  • Typical total: $60–$150 if charged separately (usually part of diagnostic or repair).

• Major engine repairs (if compression issues are found)

  • Parts + labor: Highly variable; could range from $1,000 to several thousand dollars depending on component (valves, rings, head gasket, etc.)

Important notes

• These are rough ranges. Actual pricing varies by location, shop, and vehicle specifics (engine type: 1.5L turbo vs 2.0L NA; trim level; OEM vs aftermarket parts).
• If you’re dealing with a rare or multiple root causes, total costs can exceed the individual item estimates above.

DIY vs PROFESSIONAL

• DIY viability:

  • Pros: Lower parts cost, hands-on learning, potential quick wins (spark plug changes, simple coil replacements).
  • Cons: Modern Hondas have accessible but sometimes tight engine bays; ignition coils and spark plugs require careful torque and correct gaps; misdiagnosis may lead to wasted parts and continued engine damage; risk of electrical shocks or engine damage if done incorrectly.
  • Suitable tasks for a competent DIYer: Inspecting spark plug and coil condition, swapping plugs/coils to verify fault follows, performing vacuum/air intake inspections, basic compression checks if you have the toolset.

• Professional considerations:

  • A technician can systematically test ignition, fuel, air, and compression in a controlled way, interpret freeze-frame data, and perform more precise injector testing, compression tests, and scope-based ignition analysis.
  • If the misfire is intermittent or environmental (vacuum leaks) or involves compression, a professional evaluation is advised to prevent further engine damage.

• When DIY makes sense to defer to a pro:

  • If you don’t have a torque wrench, compression tester, or access to a scope, or if the misfire persists after basic checks.
  • If the misfire is severe (flashing MIL) or you are unsure about high-voltage coil testing or fuel-injector testing.

PREVENTION

• Regular maintenance
  • Follow Honda’s recommended maintenance schedule for spark plugs, ignition coils, and fuel system services.
  • Replace spark plugs at the recommended interval with OEM or high-quality plugs suitable for your engine variant.
  • Use high-quality fuel and maintain clean fuel injectors and air intake systems.
• Fuel system care
  • Use reputable fuel brands and consider fuel system cleaners occasionally, but avoid overuse and rely on proper maintenance instead.
• Ignition system care
  • Inspect ignition coil connectors and wiring during routine maintenance; replace aging coils proactively if you notice misfire symptoms.
• Air intake and sensors
  • Replace the air filter on schedule; clean or replace MAF sensor if readings are out of spec.
• Vacuum and PCV system
  • Periodically inspect vacuum lines and PCV components; fix leaks promptly to prevent lean conditions that can contribute to misfires.
• Engine cleanliness and carbon buildup
  • On direct-injection engines, monitor carbon buildup on intake valves. If high carbon buildup is suspected or observed, consider appropriate services (professional cleaning if required per Honda guidance) to maintain efficient combustion.
• Monitor and address promptly
  • Since misfires can damage the catalytic converter, address P0302 promptly rather than driving long distances with the issue.

Key reminders

• No recalls found in NHTSA database for this make/model/year regarding P0302 in the provided data. If you’re troubleshooting, rely on your scan tool data and mechanical inspection rather than assuming a recall.
• If the Check Engine Light is flashing, it indicates a severe misfire risk and you should stop driving and seek immediate service to avoid damage to the catalytic converter or engine.

If you’d like, I can tailor a step-by-step diagnostic checklist to your exact Civic variant (trim, engine type) and give you a region-specific cost estimate from local shop rates.