If your 2020 Subaru Legacy is displaying a P0305 code indicating a cylinder 5 misfire, this code requires diagnostic investigation. The redesigned 2020 Legacy offers only four-cylinder engines: the 2.5L naturally aspirated and the 2.4L turbocharged. Neither has a cylinder 5, making P0305 technically anomalous.
2020 Legacy - New Generation
The seventh-generation 2020 Legacy was a complete redesign. Engine options include the 2.5L FB25 flat-four (182 hp) and the 2.4L FA24 turbocharged flat-four (260 hp on XT). The flat-six option from previous generations was discontinued. All 2020 Legacys have four-cylinder engines.
Why P0305 Cannot Be Valid
All 2020 Legacy engines have exactly four cylinders numbered 1-4. A P0305 code references a non-existent cylinder 5, indicating a diagnostic error.
Possible Causes
As a first-year redesign, ECM software calibration issues could store incorrect codes. Scan tool compatibility may cause errors. Low battery voltage affects ECM reliability. A 2020 model may also have battery age considerations.
Diagnostic Recommendations
Use a Subaru SSM or compatible scan tool to verify codes. Test battery condition. If actual misfire symptoms exist, focus on cylinders 1-4. Clear the erroneous code.