Applicable Systems
OBD-II
Symptoms
Cylinder 2 misfiring; rough idle, power loss; possible catalytic converter damage if persistent.
Possible Causes
- Fouled or worn spark plug on cyl 2
- Cracked ignition coil for cyl 2
- Clogged fuel injector on cyl 2
- Low compression in cyl 2
Troubleshooting Steps
- Step 1: Swap cyl 2 spark plug with cyl 1
If misfire moves to cyl 1, plug is bad - Step 2: Swap cyl 2 coil with cyl 1 coil
If misfire moves, coil is bad - Step 3: Check cyl 2 compression
Compression within spec - Step 4: Check cyl 2 injector pulse with noid
Injector pulses - Step 5: Replace faulty component
Cylinder 2 fires normally
How to Reset
Clear with OBD-II scanner after repair.
Common Replacement Parts
- Spark Plug (OEM spec)
- Ignition Coil (OEM spec)
Frequently Asked Questions
- Q: What is swap test for misfire?
Move spark plug, then coil, then injector from misfiring cylinder to known-good cylinder. If misfire follows the part, that part is defective.
Source: SAE J2012 standard DTC list + OBD-II portal
Category: OBD-II