Mazda 6 2.5 Skyactiv-G GJ

The Mazda 6 GJ uses hydraulic engine mounts that are prone to failure from around 50,000-80,000 km. The mounts contain a fluid damper that leaks over time, losing vibration-isolation properties. The torque (dogbone) mount at the top of the engine is typically the first to fail. Symptoms include noticeable vibration at idle (worse with AC on), clunking when shifting between reverse and drive, and the engine visibly rocking when revved with the brake held. All three mounts (left, right, torque) often need replacement together. OEM mounts cost approximately €80-150 each. An independent garage charges around €200-400 total for labour. Dealer quotes can reach €500 or more. This is the most commonly reported issue across Mazda 6 GJ forums.

The 2018+ Mazda 6 2.5 with automatic transmission features cylinder deactivation that shuts down cylinders 1 and 4 during light cruising. Many owners report a noticeable shudder at 70-120 km/h as the system activates and deactivates. Mazda claims this is normal behaviour, but it bothers many drivers. More seriously, recall 3719F addressed a PCM software defect that could cause a rocker arm to come out of position during the transition from two-cylinder to four-cylinder mode, risking engine misfire, loss of power, or stall. Over 300,000 vehicles were affected globally. The fix is a free PCM software update. If the recall was not performed and physical engine damage occurred, head replacement can exceed €3,000. Pre-2018 models without cylinder deactivation are unaffected. If the recall has been completed, the remaining issue is only the subjective vibration, which costs nothing to fix but annoys some owners.

Like all gasoline direct injection engines, the 2.5 Skyactiv-G sprays fuel directly into the combustion chamber rather than over the intake valves. Oil vapour from the PCV system coats the valve stems and hardens over time. Symptoms typically appear between 100,000-150,000 km: rough idle, slight misfires, hesitation on cold starts, and increased fuel consumption. Mazda's high 13:1 compression ratio helps keep valve temperatures elevated, which reduces carbon formation compared to some competitors. Walnut blasting costs approximately €300-500 at a specialist. Replacing or cleaning the PCV valve around 80,000 km helps slow the progression. Cars driven primarily on short urban trips accumulate carbon faster. Regular motorway driving at higher RPM helps delay the issue. Many owners reach 200,000 km without needing intervention.

Mazda issued TSB 01-019/19 acknowledging that the hydraulic drive belt auto tensioner can leak oil due to insufficient sealing at the damper under high ambient temperature and high load conditions. Symptoms include a rattling noise on acceleration and visible oil seepage around the tensioner. The modified replacement part (superseded to PE03-15-980C) has improved sealing. Replacement costs approximately €150-350 including the part and about one hour of labour. If the leak goes unaddressed, the serpentine belt can slip and accessories (alternator, power steering, AC compressor) lose function. The issue can appear from around 60,000 km onward and affects all Skyactiv-G applications.

This is the most commonly reported issue across all Mazda models using power folding mirrors, including the Mazda 6 GJ. The internal plastic gears degrade from repeated use and moisture ingress. One mirror typically fails first, with the other following within 6-12 months. Symptoms include grinding noises, stuttering, and incomplete folding. A full mirror assembly replacement at a Mazda dealer costs €350-500 per side. However, aftermarket repair kits with upgraded metal gears are available for €15-30 and can be fitted at a local garage for under €100 total. Disabling the auto-fold function via the mirror switch extends gear lifespan significantly.

On Mazda 6 GJ models equipped with the Bose sound system, the front door speaker cone glue degrades over time, causing the paper cone to separate from the metal frame. This creates buzzing and rattling at certain frequencies. Mazda issued a service bulletin acknowledging the issue. A new OEM Bose speaker costs approximately €150-250 per side, plus around one hour of labour. A specialist audio shop can re-glue the cone for approximately €50-80. DIY repair with adhesive is possible and essentially free. The issue affects most Bose-equipped Mazda 6 GJ models eventually, typically after 4-6 years.

Mazda issued TSBs for 2013-2016 models identifying two causes of front suspension noise. First, the bump stopper contacts the strut bearing when the front shock absorber is compressed, causing a popping sound. Second, the front lower arm bushing makes a stick-slip noise in wet road conditions. Mazda revised the strut bearing material and added a dry coating to reduce bushing friction in later production. Replacement of strut top mounts costs €150-250 per side. Lower arm bushing replacement runs €200-300 per side at an independent garage. The issue is annoying but does not affect safety or handling. Post-2016 facelift models are largely unaffected.

The oil control valves on the Skyactiv-G 2.5 use a rubber sleeve pressed into the valve cover. Over time, heat cycles cause the seal to harden and shrink, allowing oil to seep past. The leak is typically slow and visible when the engine cover is removed. For minor seepage, simply wiping it at each oil change is sufficient. If the leak worsens, replacement of the OCV seal costs approximately €100-200 for parts and €50-100 for labour. In some cases the valve cover gasket should be replaced at the same time. The issue can appear from around 80,000 km onward. Mazda does not use fasteners to secure this seal, relying instead on gasket pressure alone, which is the root cause.