What are the most common Mazda MX-5 Miata problems?
According to Au7o's analysis of 13,300+ owner reports, the 1999 Mazda MX-5 Miata has 12 documented issues. The most frequently reported are: Crankshaft Position Sensor Failure (NB), Clutch Slave Cylinder Piston Seal Leak - Sudden Loss of Clutch Release, Rocker panel and front frame-rail rust (rear of rockers / behind front wheels). Of these, 3 are rated critical and should be addressed promptly.
Is the Mazda MX-5 Miata reliable?
The 1999 Mazda MX-5 Miata has 12 known issues documented across 13,300+ owner reports. 3 issues are rated critical: Crankshaft Position Sensor Failure (NB) and Clutch Slave Cylinder Piston Seal Leak - Sudden Loss of Clutch Release and Rocker panel and front frame-rail rust (rear of rockers / behind front wheels). 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 MX-5 Miata problems?
Repair costs for known Mazda MX-5 Miata issues range from $0 to $4,000, depending on the specific problem and whether you choose DIY or professional repair. The most critical issue, Crankshaft Position Sensor Failure (NB), typically costs $50-$250 to repair. Au7o provides step-by-step DIY maintenance guides that can help reduce repair costs.
What is the 1999-2005 Mazda MX-5 Miata Crankshaft Position Sensor Failure (NB)?
The NB Miata (1999-2005) crankshaft position sensor (CPS) is a known failure point. The sensor deteriorates from engine heat, causing intermittent stalling, no-start conditions, and random misfires. Failure is often heat-related - the car runs fine when cold but stalls or dies af… Repairs typically run $50-$250. Severity: high.
What is the 1990-2008 Mazda MX-5 Miata Clutch Slave Cylinder Piston Seal Leak - Sudden Loss of Clutch Release?
The externally mounted clutch slave cylinder on NA/NB/NC Miatas fails at the piston seal. Fluid weeps past the seal and collects behind the rubber boot, then the cylinder stops holding pressure and the pedal drops to the floor with no gear engagement - frequently without warning. Repairs typically run $60-$400. Severity: high.
What is the 1990-1999 Mazda MX-5 Miata Rocker panel and front frame-rail rust (rear of rockers / behind front wheels)?
NA and NB Miatas are prone to structural rust in two well-known areas: the rear ends of the rocker panels (sills) and the front frame rails behind the front wheels. Road water enters through wheel-arch pinch welds and body seams and collects inside the double-layer sheet metal, r… Repairs typically run $500-$4,000. Severity: high.
What is the 1990-2025 Mazda MX-5 Miata Soft Top Wear and Rear Window Delamination?
Miata soft tops deteriorate over time from UV exposure, flexing during operation, and age. Vinyl tops develop cracks and tears, cloth tops fade and shrink. The rear plastic window (NA/NB) or glass window (NC/ND) can delaminate from the top material, causing water leaks and reduce… Repairs typically run $300-$1,500. Severity: medium.
What is the 1990-2015 Mazda MX-5 Miata Rear Main Seal Oil Leak?
All generations of Miata (NA through NC) are prone to rear main seal leaks as the engine ages. Oil seeps from the crankshaft rear seal, dripping onto the clutch housing and eventually contaminating the clutch disc. High mileage engines and infrequent oil changes accelerate seal d… Repairs typically run $400-$1,200. Severity: medium.
What is the 1994-2000 Mazda MX-5 Miata Early 1.8L Coil Pack Internal Igniter Failure (4-Pin Connector Coils)?
The 1994-2000 1.8L BP engines use a wasted-spark coil pack with an integrated igniter transistor. The early version (identified by the 4-pin input connector, later revised to 3-pin) is notorious for internal igniter/solder-joint failure, especially if the ignition is left in the… Repairs typically run $90-$350. Severity: medium.
What is the 1999-2005 Mazda MX-5 Miata Radiator Coolant Overflow and Cracked Upper Tank (NB)?
NB Miata radiators are prone to failure at the plastic upper tank where it crimps onto the aluminum core. The plastic becomes brittle with age and heat cycling, developing hairline cracks that leak coolant under pressure. This can lead to sudden coolant loss and overheating, espe… Repairs typically run $200-$500. Severity: medium.
What is the 1990-1999 Mazda MX-5 Miata Overdue timing belt / water pump service (age-related, both engines)?
Both the 1.6L B6 and 1.8L BP are belt-driven and Mazda specifies timing-belt replacement at 60,000 miles. On 25-35 year-old cars, belts frequently fail on age/dry-rot rather than mileage. The engines are non-interference, so a snapped belt will not bend valves, but it will strand… Repairs typically run $350-$900. Severity: medium.
What is the 1999 Mazda MX-5 Miata Fuel filler pipe non-return valve sticking / fuel spit-back (1999 NB - NHTSA recall 00V032000)?
NHTSA recall campaign 00V032000 covered approximately 22,000 1999 MX-5 Miatas built November 1997 to November 1998. Insufficient clearance between the fuel filler pipe's non-return (check) valve case and shutter, combined with fuel-hose material properties, could cause the valve… Repairs typically run $0-$300. Severity: medium.
What is the 1990-2005 Mazda MX-5 Miata Hydraulic Lash Adjuster (HLA) Tick from Restricted Oil Feed on B6/BP Engines?
The 1.6L B6 and 1.8L BP engines use hydraulic lash adjusters inside the bucket followers. Varnish and sludge from extended oil changes, or oil that is too thick or too thin, restrict flow into the adjuster so it cannot stay pumped up. The result is a persistent sewing-machine tic… Repairs typically run $60-$900. Severity: low.
What is the 1990-1999 Mazda MX-5 Miata Convertible soft-top plastic rear window cracking, hazing, and zipper tear-out?
NA and most early NB tops use a flexible plastic (vinyl) rear window, on many NA tops joined to the top with a zipper so the window can be lowered. With UV exposure and age the plastic yellows, hazes to near-opaque, and cracks (often starting at corners or the zipper seam); the z… Repairs typically run $100-$700. Severity: low.
What is the 1994-1999 Mazda MX-5 Miata Cam/Crank Angle Sensor (CAS) O-ring oil leak on 1.8L engines?
On 1.8L BP engines, the Cam Angle Sensor (commonly called the CAS) mounts at the rear of the cylinder head, engaging the camshaft, and is sealed to the head by a single rubber O-ring. With age and heat cycling the O-ring hardens and shrinks, letting oil weep out of the back of th… Repairs typically run $80-$300. Severity: low.
