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 1990-1997 Mazda MX-5 Miata Timing Belt and Water Pump Failure (NA 1.6L/1.8L)?

Both the 1.6L B6 and 1.8L BP engines in the NA Miata are interference engines that require timing belt replacement every 60,000 miles. A broken timing belt causes pistons to strike valves, resulting in bent valves and potentially damaged pistons — often totaling the engine. The w… Repairs typically run $200-$600. 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 1990-1991 Mazda MX-5 Miata Short-nose crankshaft / keyway failure on 1990-early 1991 1.6 ("the Miata crank problem")?

The earliest 1.6L B6 cars (all 1990 and 1991 up to VIN JM1NA...209446) use a 'short-nose' crankshaft. The crank pulley/timing sprocket is retained by a single bolt and a Woodruff key in a shallow keyway. Over time, and especially after a timing-belt/front-seal service where the p… Repairs typically run $150-$3,500. 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 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 2006-2015 Mazda MX-5 Miata Electric Power Steering (EPS) Failure and Warning Light (NC)?

The NC Miata uses an electric power steering system that can fail due to a faulty steering angle sensor, EPS control module, or motor. When the system fails, the EPS warning light illuminates and power assist is lost, making the steering very heavy at low speeds. While the car re… Repairs typically run $200-$1,200. 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 2016-2025 Mazda MX-5 Miata Differential Whine (ND)?

The ND Miata (2016+) rear differential produces a noticeable whine or hum at highway speeds (50-70 mph) under light load. The noise is gear mesh related and varies with speed and throttle position. While not typically indicative of imminent failure, the noise is audible in the ca… Repairs typically run $50-$1,500. Severity: low.

What is the 2016-2025 Mazda MX-5 Miata Mazda Connect Infotainment USB and Bluetooth Connectivity Issues (ND)?

The ND Miata's Mazda Connect infotainment system is plagued by USB connectivity drops, Bluetooth pairing failures, and occasional system freezes. USB-connected phones may disconnect repeatedly, and Bluetooth audio can cut out or develop significant delay. The 7-inch screen can fr… Repairs typically run $0-$500. 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.

Mazda · Known Issues

1990-2025 Mazda MX-5 Miata Problems: 15 Issues Every Owner Should Know

1990-2025 model years · 20,400+ owner reports · Updated July 2026

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According to Au7o's analysis of 20,400+ owner reports, the 1990-2025 Mazda MX-5 Miata has 15 documented known issues, with 5 rated critical. The most serious are Short Nose Crank Keyway Failure (NA 1.6L) ($50-$400 repair), Crankshaft Position Sensor Failure (NB) ($50-$250 repair), Timing Belt and Water Pump Failure (NA 1.6L/1.8L) ($200-$600 repair), Rocker panel and front frame-rail rust (rear of rockers / behind front wheels) ($500-$4,000 repair) and Short-nose crankshaft / keyway failure on 1990-early 1991 1.6 ("the Miata crank problem") ($150-$3,500 repair). The most commonly reported issue is Short Nose Crank Keyway Failure (NA 1.6L) with 6,000 owner reports. Across all issues, repair costs range from $50 to $4,000. DIY maintenance guides at au7o.io.

Frequently Asked Questions

What are the most common Mazda MX-5 Miata problems?

According to Au7o's analysis of 20,400+ owner reports, the 1990-2025 Mazda MX-5 Miata has 15 documented issues. The most frequently reported are: Short Nose Crank Keyway Failure (NA 1.6L), Crankshaft Position Sensor Failure (NB), Timing Belt and Water Pump Failure (NA 1.6L/1.8L). Of these, 5 are rated critical and should be addressed promptly.

Is the Mazda MX-5 Miata reliable?

The 1990-2025 Mazda MX-5 Miata has 15 known issues documented across 20,400+ owner reports. 5 issues are rated critical: Short Nose Crank Keyway Failure (NA 1.6L) and Crankshaft Position Sensor Failure (NB) and Timing Belt and Water Pump Failure (NA 1.6L/1.8L) and Rocker panel and front frame-rail rust (rear of rockers / behind front wheels) and Short-nose crankshaft / keyway failure on 1990-early 1991 1.6 ("the Miata crank problem"). 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, Short Nose Crank Keyway Failure (NA 1.6L), typically costs $50-$400 to repair. Au7o provides step-by-step DIY maintenance guides that can help reduce repair costs.

What year Mazda MX-5 Miata is the most reliable?

Reliability varies across model years of the Mazda MX-5 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 1990-2025 Mazda MX-5 Miata with 15 documented issues documented across 20,400+ owner reports.

What is the 1990-1993 Mazda MX-5 Miata Short Nose Crank Keyway Failure (NA 1.6L)?

Early NA Miatas (1990-1993) with the 1.6L B6ZE engine have a shorter crankshaft snout that is prone to keyway wallowing. The crankshaft pulley bolt loosens over time, causing the Woodruff key to shear and the pulley to spin freely on the crankshaft. This leads to loss of timing b… Repairs typically run $50-$400. Severity: high.

All 15 Known Issues

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Frequently Asked Questions

What are the most common Mazda MX-5 Miata problems?

Is the Mazda MX-5 Miata reliable?

How much does it cost to fix common Mazda MX-5 Miata problems?

What year Mazda MX-5 Miata is the most reliable?

What is the 1990-1993 Mazda MX-5 Miata Short Nose Crank Keyway Failure (NA 1.6L)?

1990-1993 Mazda MX-5 Miata: Short Nose Crank Keyway Failure (NA 1.6L)#

1999-2005 Mazda MX-5 Miata: Crankshaft Position Sensor Failure (NB)#

1990-1997 Mazda MX-5 Miata: Timing Belt and Water Pump Failure (NA 1.6L/1.8L)#

1990-1991 Mazda MX-5 Miata: Short-nose crankshaft / keyway failure on 1990-early 1991 1.6 ("the Miata crank problem")#

1990-2015 Mazda MX-5 Miata: Rear Main Seal Oil Leak#

1994-1999 Mazda MX-5 Miata: Cam/Crank Angle Sensor (CAS) O-ring oil leak on 1.8L engines#

1990-1999 Mazda MX-5 Miata: Rocker panel and front frame-rail rust (rear of rockers / behind front wheels)#

1990-2025 Mazda MX-5 Miata: Soft Top Wear and Rear Window Delamination#

1990-1999 Mazda MX-5 Miata: Convertible soft-top plastic rear window cracking, hazing, and zipper tear-out#

1999-2005 Mazda MX-5 Miata: Radiator Coolant Overflow and Cracked Upper Tank (NB)#

1990-1999 Mazda MX-5 Miata: Overdue timing belt / water pump service (age-related, both engines)#

2006-2015 Mazda MX-5 Miata: Electric Power Steering (EPS) Failure and Warning Light (NC)#

1999 Mazda MX-5 Miata: Fuel filler pipe non-return valve sticking / fuel spit-back (1999 NB - NHTSA recall 00V032000)#

2016-2025 Mazda MX-5 Miata: Differential Whine (ND)#

2016-2025 Mazda MX-5 Miata: Mazda Connect Infotainment USB and Bluetooth Connectivity Issues (ND)#