A P0303 code in your 2020 Subaru Legacy indicates the engine control module has detected excessive misfires at cylinder 3. The redesigned 2020 Legacy offers the 2.5L naturally aspirated boxer four-cylinder (182 horsepower) and the 2.4L turbocharged boxer four-cylinder (260 horsepower). Subaru's horizontally opposed engine design affects diagnosis approach.
Cylinder 3 in Subaru's Boxer Engine
The boxer configuration positions cylinders horizontally opposed. Cylinder 3 is located on the passenger side, toward the rear near the firewall. This unique layout provides excellent balance and low center of gravity but affects component accessibility.
Engine Options
The base 2.5L offers smooth, naturally aspirated power. The 2.4L XT turbo provides significantly more performance for those wanting spirited acceleration. Turbocharged engines operate under higher cylinder pressures, demanding more from ignition components.
Common P0303 Causes at Four to Five Years
At this age, wear-related issues become more likely. Spark plugs may be approaching replacement interval. Ignition coils degrade from heat cycling. Carbon buildup from direct injection affects airflow. Fuel injector deposits accumulate.
Seventh-Generation Legacy
The 2020 model introduced the seventh-generation Legacy with updated powertrains and technology, including the new 2.4L turbocharged engine option.