What are the most common Mazda Miata problems?
According to Au7o's research across NHTSA recalls, manufacturer TSBs, and owner forum reports, the 1990-2005 Mazda Miata has 6 documented issues. The most frequently reported are: Crankshaft Thrust Bearing Failure (1999-2000 BP-4W 1.8L), Short-Nose Crankshaft Keyway Wear (1990-1991 B6 1.6L), Structural Rust at Rear Rocker Panels and Front Frame Rails. Of these, 3 are rated critical and should be addressed promptly.
Is the Mazda Miata reliable?
The 1990-2005 Mazda Miata has 6 known issues compiled from NHTSA recalls, manufacturer TSBs, and owner forum reports. 3 issues are rated critical: Crankshaft Thrust Bearing Failure (1999-2000 BP-4W 1.8L) and Short-Nose Crankshaft Keyway Wear (1990-1991 B6 1.6L) and Structural Rust at Rear Rocker Panels and Front Frame Rails. Prospective buyers should inspect for these issues and factor potential repair costs into their purchase decision. Regular maintenance following the manufacturer's schedule helps prevent many common problems.
How much does it cost to fix common Mazda Miata problems?
Repair costs for known Mazda Miata issues range from $4 to $5,000, depending on the specific problem and whether you choose DIY or professional repair. The most critical issue, Crankshaft Thrust Bearing Failure (1999-2000 BP-4W 1.8L), typically costs $1,200-$4,500 to repair. Au7o provides step-by-step DIY maintenance guides that can help reduce repair costs.
What year Mazda Miata is the most reliable?
Reliability varies across model years of the Mazda Miata. Based on documented issues, problems are most commonly reported in earlier model years. Au7o recommends checking the specific known issues for your target year before purchasing, and having a pre-purchase inspection performed by a qualified mechanic. Our known issues database covers the 1990-2005 Mazda Miata with 6 documented issues compiled from NHTSA recalls, manufacturer TSBs, and owner forum reports.
What is the 1999-2000 Mazda Miata Crankshaft Thrust Bearing Failure (1999-2000 BP-4W 1.8L)?
A well-documented manufacturing defect in 1999-2000 NB1 Miatas: the #4 main cap block support was machined with an excessively deep thrust bearing recess, and the factory installed standard-thickness thrust bearings regardless of clearance. The undersized bearing allows the crank… Repairs typically run $1,200-$4,500. Severity: high.
What is the 1990-1991 Mazda Miata Short-Nose Crankshaft Keyway Wear (1990-1991 B6 1.6L)?
Early 1990-1991 Miatas (VIN 209446 and below) were built with a smaller-diameter crankshaft nose (short-nose crank, or SNC) and a 4-slot crank pulley. The design is intolerant of assembly errors and high accessory belt loads: incorrect key installation, improper pulley bolt torqu… Repairs typically run $800-$3,500. Severity: high.
What is the 1990-2005 Mazda Miata Structural Rust at Rear Rocker Panels and Front Frame Rails?
Both NA and NB Miatas are notorious for hidden structural rust, most commonly at the rear ends of the rocker panels and (especially on NBs) the front frame rails where they meet the floor pan. Water enters via the wheel-arch pinch welds and clogged convertible-top/trunk drain cha… Repairs typically run $400-$5,000. Severity: high.
What is the 1990-2005 Mazda Miata Clutch Slave Cylinder Hydraulic Failure?
The clutch slave cylinder on both NA and NB Miatas is a known wear item — internal seals deteriorate with age and brake fluid contamination, allowing hydraulic fluid to leak past the piston seal. Because the slave's rubber boot can hold a surprising amount of fluid before any ext… Repairs typically run $30-$350. Severity: medium.
What is the 1990-1997 Mazda Miata Convertible Top Rear Plastic Window Cracking and Zipper Failure (NA)?
Original 1990-1997 NA Miatas were fitted with a vinyl convertible top featuring a zippered, clear plastic rear window. The plastic yellows, crazes, and cracks with UV exposure, and folding the top with the window zipped in causes creases that progress to permanent fractures. Addi… Repairs typically run $4-$1,600. Severity: low.
What is the 1990-2005 Mazda Miata Crank Angle Sensor O-Ring and Valve Cover Gasket Oil Leaks?
Two related oil leaks plague essentially every B6 and BP Miata as it ages. (1) The crank angle sensor (CAS, also called the cam angle sensor) at the rear of the cylinder head uses a small O-ring that hardens with age and seeps oil down the back of the block. Because the leak runs… Repairs typically run $30-$350. Severity: low.
