Mazda 6
2.0-litre common-rail diesel in various development stages (RF4F, RF5C, RF7J). Solid everyday diesel with good torque.
Manual Gearbox Fun
The 2.0L works well with the short throw. No sports car, but an honest driver's car with a good platform.
Engine Weaknesses 7
The RF diesel is an interference engine. If the timing belt snaps, pistons and valves collide — the cylinder head must be replaced. Change interval: 80,000 km or 8 years.
Symptoms: Engine won't start after belt snap, no compression, metallic noises on start attempts
The solenoid valve beneath the injection pump leaks. Diesel seeps out and can attack coolant hoses and wiring looms. Diesel specialists replace only the valve rather than the entire pump.
Symptoms: Diesel smell in engine bay, visible fuel moisture beneath the injection pump, swollen coolant hoses
The Denso injection driver module (IDM, RF2A-18-701A) under the intake manifold develops earthing problems with age. Fault codes are often not set — difficult to diagnose.
Symptoms: Engine barely responds to throttle when cold, jerky acceleration below 1,500 rpm, normal behaviour above 2,500 rpm
The injector flame seals become porous and leak from around 120,000 km. Diesel mixture escapes and mixes with the engine oil, causing a sharp rise in oil consumption. A known production issue on the RF diesel engine.
Symptoms: Dark, heavily diluted engine oil; elevated oil consumption up to 1 litre/500 km; faint diesel smell at the engine.
The conical seating faces where the high-pressure fuel lines screw into each cylinder can develop leaks. Diesel smell after driving and persistently damp spots on the cylinder head are typical signs.
Symptoms: Strong diesel smell after shutdown; damp spots at line connections on the cylinder head; no visible leak when stationary.
The alternator of the RF diesel engine can fail from around 150,000 km due to bearing failure or regulator faults. The battery is no longer charged and the charge warning light illuminates.
Symptoms: Charge warning light on; battery discharges while driving; vehicle stalls.
The EGR valve carbons up and causes rattling noises and power loss. There are also wiring issues at the EGR electrics that promote temperature-dependent failures.
Symptoms: Rattling from the intake area, power loss especially after rain or cold start, impaired turbo response
Vehicle Weaknesses 6
The Mazda 6 GH shows corrosion on door edges, sills and wheel arches. Less pronounced than on the GG, but vehicles without cavity wax treatment show clear rust onset after several years.
Seized rear brake calipers are a cross-generational Mazda 6 weakness. The integrated handbrake mechanism corrodes and can only be permanently resolved by replacement.
Control arm bushings and ball joints on the Mazda 6 GH front axle wear noticeably at higher mileage. MOT reports confirm above-average axle defects on the GH.
On the Mazda 6 GH with manual gearbox, especially the 2.2 diesel, 1st and 2nd gear are difficult to engage when cold. Synchro rings do not function correctly with the wrong gear oil.
Steering wheel judder when braking caused by warped brake discs is a well-known Mazda 6 weakness across all generations. On the GH it often appears from 50,000 km and returns after standard repairs.
Tail lights and rear lights on the Mazda 6 GH fail prematurely. Moisture ingress or internal short circuits can cause entire light units to malfunction.