Cylinder 2 Misfire Detected
P0302 indicates that cylinder 2 is misfiring, meaning the air-fuel mixture in that cylinder is not igniting properly on one or more combustion cycles. This is most often caused by a faulty ignition coil, bad spark plug, or fuel delivery issue, and must be diagnosed and repaired to prevent engine damage and excessive emissions.
What You Might Notice
- Rough or unstable idle
- Loss of power during acceleration
- Engine hesitation or stumbling
- Unusual smell from exhaust
- Check engine light illuminated
Most Common Causes
- 1
Faulty Ignition Coil
The ignition coil for cylinder 2 may be failing or producing insufficient spark voltage. This is the most common cause of misfire codes and can be tested with an ohmmeter or by swapping coils between cylinders.
- 2
Defective Spark Plug
The spark plug in cylinder 2 may be worn, fouled, or gapped incorrectly, preventing proper ignition of the fuel mixture. Inspect the plug for carbon buildup, electrode erosion, or improper gap.
- 3
Fuel Delivery Problem
A clogged fuel injector, failing fuel pressure regulator, or low fuel pressure can prevent proper fuel supply to cylinder 2. This results in a lean mixture that may not ignite reliably.
- 4
Vacuum Leak or Compression Loss
A large vacuum leak affecting cylinder 2 or loss of compression from a bent valve or damaged piston ring can cause a lean condition or prevent proper combustion.
How to Diagnose It
- 1
Check Faulty Ignition Coil — The ignition coil for cylinder 2 may be failing or producing insufficient spark voltage. This is the most common cause of misfire codes and can be tested with an ohmmeter or by swapping coils between cylinders.
- 2
Check Defective Spark Plug — The spark plug in cylinder 2 may be worn, fouled, or gapped incorrectly, preventing proper ignition of the fuel mixture. Inspect the plug for carbon buildup, electrode erosion, or improper gap.
- 3
Check Fuel Delivery Problem — A clogged fuel injector, failing fuel pressure regulator, or low fuel pressure can prevent proper fuel supply to cylinder 2. This results in a lean mixture that may not ignite reliably.
- 4
Check Vacuum Leak or Compression Loss — A large vacuum leak affecting cylinder 2 or loss of compression from a bent valve or damaged piston ring can cause a lean condition or prevent proper combustion.
How to Fix It
- 1
Replace Ignition Coil for Cylinder 2
Remove the faulty coil-over-plug from cylinder 2 and install a new OEM or quality aftermarket replacement. Ensure proper seating and electrical connector alignment.
- 2
Inspect and Replace Spark Plug
Remove the spark plug from cylinder 2, inspect its condition, and replace with a new plug at the manufacturer's specified gap. Clean any carbon deposits from the combustion chamber if present.
- 3
Check and Clean Fuel Injector
Test fuel pressure at the rail and inspect the cylinder 2 injector for proper spray pattern. Clean or replace the injector as needed, and verify fuel pressure meets specification (typically 45-65 PSI depending on vehicle).
- 4
Perform Compression and Vacuum Tests
Conduct a cylinder compression test to rule out mechanical engine problems such as bent valves or ring wear. Check for vacuum leaks using smoke test or by listening for hissing sounds around intake gaskets and hoses.
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