Mazda 5 2.0 CD CR

This is the RF7J engine's most serious design flaw. The original triangular-shaped copper injector seals deteriorate over time, allowing hot combustion gases past the seal into the camshaft area. These gases cook the engine oil, producing hard carbon deposits that circulate through the oil system and eventually block the oil pump suction strainer, starving the engine of oil pressure. Symptoms include a ticking noise from the injectors, oil discoloration, and in severe cases the low oil pressure warning light. Mazda issued a technical bulletin and revised the seal design (tinned copper washers with a new tightening procedure). Repair involves removing the injectors, cleaning the pockets, fitting new-design seals, and cleaning the oil strainer. If caught early, this costs around €800-1,200. If the engine has sustained bearing damage from prolonged oil starvation, a rebuild or replacement can reach €3,000-3,500. Any used Mazda 5 2.0 CD should have the revised seals fitted as an absolute minimum.

The 2.0 MZR-CD's DPF management is widely considered poorly executed. Unlike most competitors, the system provides no dashboard indication that a regeneration cycle is in progress or needed. If the car is switched off mid-regeneration, the process stops and unburned fuel washes past the piston rings into the sump oil, raising the oil level and diluting the lubricant. Cars driven predominantly on short urban trips rarely complete a full regeneration cycle. Over time, fuel dilution accelerates wear on all engine internals and compounds the injector seal problem. Professional DPF cleaning costs €250-400. A clogged unit needing replacement runs €1,000-2,000 including fitting. Using the correct ACEA C1 low-ash oil is essential, as standard ACEA C3 oil generates more ash and accelerates clogging.

The Mazda 5 CR has well-documented corrosion problems that were a known weakness during its production years. Rust typically starts on the inner sills, rear wheel arches, and subframe mounting points. In salt-road climates across northern and western Europe, corrosion can begin within 5-7 years and progress to structural levels within 10-15 years. Cars without aftermarket cavity wax treatment are particularly vulnerable. The area around the rear heat shield and muffler is also prone to severe corrosion. Repair costs range from around €500 for minor cosmetic treatment to €2,000-3,000 for structural sill or subframe repairs. Advanced corrosion can make the car uneconomical to repair and may result in MOT/TUV failure. A thorough underbody inspection on a lift is essential before any purchase.

The IHI RHV4 VJ36 variable geometry turbo uses small internal vanes to regulate boost pressure. Over time, especially with gentle driving and short trips, these vanes become coated in soot and carbon and can seize. Symptoms include no boost below 2,500 rpm followed by a sudden surge of power, engine warning lights, and limp mode. In some cases the actuator mechanism itself fails. If caught early, a turbo clean (removing and manually cleaning the vanes) costs around €400-600. If the turbo internals are damaged or the actuator has failed, replacement with a reconditioned unit runs €1,200-1,800. Regular driving that keeps the engine above 2,500 rpm helps prevent carbon buildup on the vanes.

Carbon buildup on the EGR valve is common on the MZR-CD diesel, particularly for cars used on short trips. Symptoms include rough idle, hesitation on acceleration, excessive black smoke, and occasional stalling. The EGR valve can usually be cleaned rather than replaced, which saves considerable money. Removal and cleaning takes several hours of labor due to limited accessibility. Cleaning costs €200-300 at an independent garage, while replacement with a new valve runs €400-500 fitted. Most owners report needing EGR attention every 60,000-80,000 km.

The diesel model uses a dual mass flywheel to absorb drivetrain vibrations from the diesel's high-torque delivery. These wear gradually, producing a rattling or knocking noise at idle that disappears when the clutch pedal is pressed. The DMF cannot be resurfaced and must be replaced as a unit. Parts cost €400-600 for an aftermarket unit (LuK or Sachs), with labor adding another €400-600 due to the gearbox removal procedure. Most specialists recommend replacing the clutch disc and pressure plate at the same time, bringing total cost to €1,000-1,800. Typically needed between 120,000-180,000 km depending on driving style. Urban stop-start driving accelerates wear significantly.

The original rear shock absorber top mounts are made from aluminum, which is prone to galvanic corrosion when exposed to road salt and moisture. As the mount weakens, it can fracture entirely, producing a loud rattling noise over bumps. This typically occurs between 60,000-100,000 km in salt-road climates. Mazda does not sell the top mount separately, requiring purchase of the complete shock absorber assembly. Most aftermarket rear shocks do not include this mount either. Some owners have adapted alternative mounts as a more affordable workaround. Replacing both rear shocks with OEM assemblies at an independent workshop costs €300-600.

The sliding rear doors are a defining feature of the Mazda 5 but their mechanical components wear with use. Common failures include the internal cable snapping or stretching, the door handle mechanism breaking at a small groove that holds the return spring, and the latch assembly freezing in cold weather. Symptoms include a door that will not open or close fully, a handle that pulls without releasing the door, or doors that refuse to latch securely. Individual cable or latch repair costs €200-350, while a full roller and track overhaul can reach €500-600 per side. Keeping the tracks and latches lubricated with silicone grease helps extend component life.