Mazda Mx 5 Problems & Known Issues

The rear sills on NB MX-5s are prone to corrosion from the inside out, particularly where the hood frame drain channels allow water to collect. This affects the structural integrity of the passenger cell and is the most common MOT failure reason for this generation. The outer sill skin often appears solid while the inner structure is severely compromised. UK cars are particularly affected due to road salt and damp climate.

The front and rear suspension mounting points are susceptible to corrosion that can weaken the attachment points to dangerous levels. This particularly affects the front upper wishbone mounts on the inner wing and rear suspension mounting points in the boot area. MOT data shows this model fails at 62.6 times the fleet average for mounting point corrosion, making it one of the most common failure modes.

The BP-ZE and BP-4W engines use an interference timing belt system where belt failure causes valve-to-piston contact and expensive internal damage. Mazda specifies 80,000 mile or 8-year intervals but the belt must be replaced regardless of condition within this timeframe. This is scheduled maintenance rather than a fault, but failure to service the belt results in catastrophic engine damage.

MX-5 suspension bushes and joints wear at significantly higher rates than average due to the car's sporting suspension setup and enthusiast driving patterns. MOT data shows failure rates of 78.3 times the fleet average, with particular problems in upper and lower wishbone bushes, anti-roll bar links, and ball joints. The rear upper arm bushes are especially prone to splitting.