Engine vibration at idle on your 2016 Hyundai Accent with code P0302 indicates cylinder 2 is misfiring, creating an imbalanced engine that shakes when it should run smooth. Addressing the misfire will eliminate the vibration.
Why Misfires Cause Vibration
Each cylinder contributes power in sequence, creating smooth engine rotation. When cylinder 2 misfires, it doesn't contribute its power stroke, unbalancing the engine. This imbalance is felt as vibration, particularly at idle when there's no motion or road noise to mask it.
Common Cylinder 2 Misfire Causes
On the Accent's 1.6L engine, cylinder 2 misfires commonly result from worn or fouled spark plug, failed ignition coil, fuel injector problem, vacuum leak near cylinder 2, and low compression from mechanical issue. Single-cylinder codes usually point to cylinder-specific components.
Diagnostic Approach
The quickest test is swapping the cylinder 2 ignition coil with another cylinder. If the code moves to the new cylinder, the coil is bad. Inspect the cylinder 2 spark plug for wear, damage, or fouling. Check for vacuum leaks around the intake near cylinder 2. Test fuel injector operation.
Compression Considerations
If ignition and fuel components check out, test compression on cylinder 2 and compare to other cylinders. Low compression indicates valve, head gasket, or piston ring problems. Significant compression difference requires more involved repair.
Repair and Results
Replace the faulty component identified through testing. Clear the code and test drive. The vibration should disappear when all cylinders fire properly. If using this opportunity to replace spark plugs, replace all four for consistent performance.