P0302 – Cylinder 2 Misfire Detected means the engine control unit has identified that **cylinder 2 is not firing correctly**. A misfire in one cylinder may cause rough running, hesitation, loss of power, poor fuel economy, and potential catalytic converter damage if left untreated. The root cause can originate from ignition, fuel delivery, air metering, or mechanical faults. This guide explains what P0302 means, the symptoms, causes, diagnosis steps, and the best repair solutions to restore smooth performance.
What Does P0302 Mean?
P0302 is a generic OBD-II powertrain code indicating a misfire has been detected specifically in **cylinder 2**. The ECU identifies misfires by monitoring crankshaft speed fluctuations as each cylinder fires. If cylinder 2 does not produce the expected torque contribution, the ECU logs P0302.
Misfires should be repaired quickly to prevent catalytic converter overload, as unburned fuel entering the exhaust can cause overheating and permanent damage.
Quick Reference
- OBD-II Family: P-Code (Powertrain)
- Scope: Generic
- System: Ignition / Fuel / Air / Mechanical
- Difficulty Level: Easy–Moderate
- Estimated Repair Cost: €50–€350+
- Last Updated: 5 December 2025
Real-World Example / Field Notes
A hatchback came in with a rough idle and noticeable hesitation during acceleration. Misfire counters showed consistent misfires on cylinder 2. After swapping ignition coils, the misfire followed the coil—confirming a failing coil pack. Installing a new coil and spark plug resolved the issue immediately.
Another case involved a vehicle that misfired only on cold mornings. The injector for cylinder 2 was partially clogged, creating a lean misfire until the engine warmed up. Professional injector cleaning restored proper fuel delivery and eliminated P0302.
Symptoms of P0302 – Cylinder 2 Misfire Detected
- Rough idle: Engine shakes or vibrates at low RPM.
- Loss of power: Hesitation or stumbling when accelerating.
- Poor fuel economy: Misfires waste fuel and reduce efficiency.
- Flashing or steady check engine light: Misfire detected, severity varies.
- Strong fuel smell: Unburned fuel may exit through the exhaust.
- Engine stalling: Severe misfires can interrupt combustion stability.
Common Causes of P0302
Most Common Causes
- Worn or fouled spark plug in cylinder 2
- Faulty ignition coil or coil boot
- Failing or clogged fuel injector (cylinder 2)
- Vacuum leak near the intake runner for cylinder 2
- Contaminated or failing mass airflow (MAF) sensor
Less Common Causes
- Low compression from valve or piston issues
- Failing camshaft or crankshaft position sensor
- Fuel pressure too low due to pump or regulator issues
- ECU driver fault (rare)
- Carbon buildup affecting airflow or sealing in cylinder 2
Diagnosis: Step-By-Step Guide
Diagnosing P0302 requires systematic inspection of ignition components, fuel delivery, airflow metering, and mechanical integrity.
Tools You’ll Need
OBD-II scan tool with misfire counters, spark tester, compression gauge, multimeter, fuel pressure gauge, smoke machine, and basic tools.
- Check freeze-frame data: Identify engine conditions when the misfire occurred.
- Inspect cylinder 2 spark plug: Look for wear, fouling, cracks, or oil contamination.
- Swap ignition coils: Move coil 2 to another cylinder—if the misfire follows, the coil is faulty.
- Test injector function: Use an injector balance test to check flow and spray pattern.
- Check for vacuum leaks: Smoke test around the intake runner for cylinder 2.
- Review fuel trims: Lean trims point to air leaks; rich trims may indicate injector issues.
- Clean or test the MAF sensor: A failing MAF can cause uneven fuel distribution.
- Check fuel pressure: Confirm pump and regulator are delivering adequate pressure.
- Perform compression test: Low compression highlights mechanical problems.
- Verify timing signals: Improper cam/crank synchronization may intermittently affect specific cylinders.
Pro Tip: If the misfire appears during high RPM or full-throttle acceleration, suspect an ignition coil or spark plug breakdown — heat and load expose weak components first.
Possible Fixes & Repair Costs
- Replace spark plug (cylinder 2): €20–€60
- Replace ignition coil: €50–€120
- Clean or replace fuel injector: €120–€250
- Repair vacuum leak: €50–€150
- Clean or replace MAF sensor: €20–€150
- Repair mechanical issues: €300–€900+
Can I Still Drive With P0302?
Driving with P0302 is risky. While the engine may still run, unburned fuel can rapidly overheat and damage the catalytic converter. If the check engine light is flashing, stop driving immediately to prevent severe damage and potential safety issues.
Related Codes
- P0399 – Ignition Coil “R” Primary/Secondary Circuit
- P0364 – Reserved
- P0363 – Misfire Detected Fueling Disabled
- P0362 – Ignition Coil “L” Primary/Secondary Circuit
- P0361 – Ignition Coil “K” Primary/Secondary Circuit
- P0360 – Ignition Coil “J” Primary/Secondary Circuit
- P0359 – Ignition Coil “I” Primary/Secondary Circuit
- P0358 – Ignition Coil “H” Primary/Secondary Circuit
- P0357 – Ignition Coil “G” Primary/Secondary Circuit
- P0356 – Ignition Coil “F” Primary/Secondary Circuit
Key Takeaways
- P0302 means cylinder 2 is misfiring and needs immediate diagnosis.
- Most common causes: spark plug, ignition coil, injector, or vacuum leak.
- A flashing MIL indicates dangerous catalyst-damaging misfires.
- Most repairs are affordable when diagnosed early.
FAQ
What is the most common cause of P0302?
Failing ignition coils and worn spark plugs are the most common root causes.
Can a vacuum leak cause a cylinder-specific misfire?
Yes. A leak near the intake runner for cylinder 2 affects air distribution and can cause a lean misfire.
Can I drive with a cylinder 2 misfire?
No. Misfires can quickly damage the catalytic converter and create unsafe driving conditions.
How do I know if the injector is the problem?
Use an injector balance test or swap injectors between cylinders to see if the misfire follows.
Should I replace all coils if one fails?
Not required, but on high-mileage vehicles, replacing coils in sets can prevent repeat failures.