Scion xB persistent decrease in gas mileage from 28 mpg to 24.5 mpg after maintenance on Scion xB

Some Scion xB owners report experiencing a decrease in gas mileage from 28 mpg to 24.5 mpg after maintenance, which may be attributed to several factors. These owners note that the check engine light being on could indicate diagnostic trouble codes in the vehicle's PCM that affect performance. Additionally, improper maintenance, such as poorly executed spark plug replacements, can significantly impact fuel efficiency. Changes in driving conditions, such as increased city driving, are also cited as contributing to lower gas mileage. Furthermore, a faulty coolant thermostat may prevent the engine from reaching optimal operating temperature, further reducing efficiency. Lastly, driving habits, including maintaining a steady speed and ensuring proper tire inflation, are emphasized as crucial for improving fuel economy. Addressing these issues may help Scion xB owners enhance their vehicle's gas mileage.