If your 2020 Subaru Ascent is displaying a P0305 code indicating a cylinder 5 misfire, this code requires diagnostic investigation. The 2020 Ascent uses a 2.4L turbocharged flat-four engine as its sole powertrain. With only four cylinders numbered 1-4, P0305 is technically anomalous.
2020 Ascent Powertrain
The first-generation 2020 Ascent uses the 2.4L FA24 turbocharged flat-four producing 260 horsepower. This is the only engine available on Subaru's three-row SUV. Despite being Subaru's largest vehicle, it uses a four-cylinder rather than a six-cylinder engine.
Why P0305 Cannot Be Valid
The Ascent's 2.4L turbo flat-four has exactly four cylinders. A P0305 code references a non-existent cylinder 5, indicating a diagnostic error rather than an actual misfire.
Possible Causes
A 2020 model may have battery degradation affecting ECM reliability. Scan tool communication errors may misread data. ECM software issues can store invalid codes. Aftermarket diagnostic tools may have compatibility issues.
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 and monitor.