Mass air flow sensors fail most often in cars but a $20 air filter replacement every 12,000 miles prevents the $250-400 repair bills most drivers face.

A $20 PCV valve failure can cause catastrophic engine damage costing thousands, but simple preventive maintenance every 60,000 miles protects your car.

Symptoms of a malfunctioning NOx sensor include increased fuel consumption, as well as reduced power and acceleration. If a sensor fails, it will also trigger an on-board diagnostic (OBD) code, ...