Vehicles using FB25 engine list:

Engine FB25

Symptoms:
- Excessive oil consumption
- Rough idling or misfires
- Engine knocking or unusual noises
- Check Engine Light illumination
- Reduced fuel efficiency

Diagnosis:
- Inspect for oil leaks around valve cover gaskets and piston rings
- Perform a compression test to check cylinder health
- Scan for diagnostic trouble codes (DTCs) related to ignition or fuel systems
- Check for carbon buildup on intake valves and combustion chambers
- Listen for abnormal engine noises indicating bearing or piston issues

Fixes:
- Replace faulty valve cover gaskets to stop oil leaks
- Repair or replace piston rings if oil consumption is excessive
- Clean or replace ignition coils and spark plugs to resolve misfires
- Use fuel system cleaners or perform walnut shell blasting to remove carbon deposits
- Address engine knocking by checking and replacing worn bearings or adjusting ignition timing
- Update engine control unit (ECU) software if manufacturer recalls or service bulletins exist

Prevention:
- Use high-quality synthetic oil and adhere strictly to oil change intervals
- Avoid extended idling and aggressive driving to reduce engine stress
- Regularly inspect and maintain ignition components
- Use recommended fuel grades to prevent knocking and carbon buildup
- Follow Subaru’s maintenance schedule for timing belt and other critical components
- Keep the air intake system clean to ensure proper combustion and engine performance