The 2019 Nissan Altima triggering P0301 indicates a specific misfire in cylinder 1. This popular sedan uses either a 2.5-liter four-cylinder or 2.0-liter turbo engine, and cylinder 1's location at the front makes diagnosis accessible.
Cylinder 1 Location
On the Altima's inline-four engines, cylinder 1 is at the front of the engine (timing chain end). This position places it closest to cooling system airflow but also subjects it to the most thermal cycling from cold starts.
Misfire Symptoms
A cylinder 1 misfire produces rhythmic roughness at idle. You may notice slight vibration through the steering wheel or seat. The check engine light may flash during severe misfires. Power loss may be noticeable during acceleration.
Ignition Coil Testing
The Altima uses coil-on-plug ignition. Swap the cylinder 1 coil with another cylinder—if the misfire moves, the coil has failed. Inspect for cracks, carbon tracking, or boot damage that could cause arcing.
Spark Plug Inspection
Remove and examine the cylinder 1 spark plug. Check electrode wear, gap measurement, and deposit patterns. Oily deposits suggest valve seal or ring issues. White deposits may indicate coolant intrusion or lean conditions.
Fuel Injector Issues
The QR25DE and VC-Turbo engines use direct injection (turbo) or port injection (2.5L). Test injector operation and spray pattern. Clogged or stuck injectors prevent proper fuel delivery.
Repair Costs
Ignition coil replacement costs $80-150 at Nissan dealers. Spark plug replacement runs $100-200 for the set. Fuel injector replacement ranges $200-400 per injector.