How to Fix Engine Backfires. 1  Step 1: Check Engine Light. 2  Step 2: Checking Fuel System Pressure. 3  Step 3: Service or Replace the Mass Air Flow Sensor. 4  Step 4: Check the Air Intake Boot or Tube. 5  Step 5: Check for Vacuum Leaks. 6  Step 6: Worn or Shorted Spark Plugs. 7  Step 7: Check the Camshaft. 8  Step 1: Upstream Exhaust Leak. 9  Step 2: Check the Gulp Valve.