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Mazda · Known Issues

1994 Mazda MX-5 Miata Problems: 11 Known Issues

1994 model year · 8,800+ owner reports · Updated September 2026

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Issue summary

According to Au7o's analysis of 8,800+ owner reports, the 1994 Mazda MX-5 Miata has 11 documented known issues, with 3 rated critical. The most serious are Clutch Slave Cylinder Piston Seal Leak - Sudden Loss of Clutch Release ($60-$400 repair), Timing Belt and Water Pump Failure (NA 1.6L/1.8L) ($200-$600 repair) and Rocker panel and front frame-rail rust (rear of rockers / behind front wheels) ($500-$4,000 repair). The most commonly reported issue is Soft Top Wear and Rear Window Delamination with 5,000 owner reports. Across all issues with published estimates, repair costs range from $40 to $4,000. DIY maintenance guides at au7o.io.

In This Article

  • MX-5 Miata Engine4
  • MX-5 Miata Transmission1
  • MX-5 Miata Body/Panels1
  • MX-5 Miata Exterior2
  • MX-5 Miata Electrical2
  • MX-5 Miata Cooling1
  • FAQ
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In This Article

  • Engine4
  • Transmission1
  • Body/Panels1
  • Exterior2
Electrical
2
  • Cooling1
  • FAQ
  • All 11 Known Issues

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    On the 1990-1997 Mazda MX-5 Miata, 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 water pump, driven by the timing belt, frequently leaks around the same interval and should be replaced proactively.

    Common Symptoms

    • High mileage since last belt change
    • Squealing from timing belt area
    • Coolant leak from water pump weep hole
    • Visible cracking on timing belt (if inspected)
    • Engine suddenly dies and will not restart (if belt breaks)

    How to Fix

    Replace the timing belt, water pump, front crank seal, cam seals, tensioner spring, and idler pulley as a complete kit every 60,000 miles. Quality kits from Gates or Continental are available for $80-$150. This is a popular DIY job (4-6 hours) with excellent online guides. Do not skip or delay this service — engine replacement after belt failure costs $1,500-$3,000.

    Typical repair cost:$200 - $600

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    Community Reported
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    Community reported
    3,800 owners

    On the 1990-2015 Mazda MX-5 Miata, 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 deterioration. This is a labor-intensive repair as the transmission must be removed.

    Common Symptoms

    • Oil dripping from bell housing area (bottom of engine/transmission junction)
    • Oil smell when parked
    • Clutch slipping if oil contaminates clutch disc
    • Low oil level between changes

    How to Fix

    Replace rear main crankshaft seal. Since the transmission must be removed, replace the clutch, throwout bearing, and pilot bearing at the same time if they are worn. Clean bell housing thoroughly to remove oil contamination.

    What you need to fix it

    Only diagnosis- and fitment-reviewed repair parts are linked here.

    • Genuine Mazda BP05-11-312 rear main seal
      OEMMazda BP05-11-312

      Rear crankshaft seal after leak-source diagnosis for the corrected NA/NB branch Fitment/availability: The inspected direct OEM page lists BP05-11-312 as the rear crankshaft oil seal, replacing B630-11-312, for 1990-1997 and 1999-2005 Mia…

      MazdaPartsNow
    • Genuine Mazda 903-465 NC rear main seal
      OEMMoss 903-465 / genuine Mazda NC rear main seal

      Confirm whether the exact repa

      Moss Miata

    As an Amazon Associate, we earn from qualifying purchases; other part links may also earn au7o a commission. Confirm fitment by VIN before buying.

    Owner tips & cautions

    • TipReplace clutch, throwout bearing, and pilot bearing during rear main seal job - saves labor
    • TipUse Mazda OEM seal over aftermarket - better fitment and longevity. Miata.net seal replacement guide
    • TipA small amount of seepage is normal on high-mileage Miatas - only repair if dripping
    Typical repair cost:$400 - $1,200

    Research This Issue

    Based on 3,800 owner reports

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    Community Reported
    High ConfidenceVerified3,800 owner reportsLast reported by owners Oct 2024Reviewed Feb 2026

    On the 1990-2005 Mazda MX-5 Miata, 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 tick from the top of the engine, loudest on cold start and often not fully quiet once warm. It is frequently misdiagnosed by inexperienced buyers as rod knock, which is a deeper, lower-pitched noise from the bottom end.

    Common Symptoms

    • Fast ticking from the top of the engine on cold start
    • Tick that persists or only partially quiets when warm
    • Noise worse with old or wrong-viscosity oil
    • One cylinder noticeably noisier than the rest

    How to Fix

    Start with an oil and filter change to the correct grade (5W-30 is the community consensus for a healthy engine) - this alone silences a large share of cases. A short interval on a high-detergent oil helps clear varnish from the adjuster feed. If a single adjuster remains noisy, individual HLAs can be replaced with the cam off; Mazda released a revised adjuster with larger oil holes. Confirm the noise is valvetrain rather than bottom end before spending money.

    Typical repair cost:$60 - $900

    Research This Issue

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    Community Reported
    Medium ConfidenceVerifiedReviewed Aug 2026

    On the 1994-1999 Mazda MX-5 Miata 1.8L BP, 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 the head. This is widely cited as the single most common oil-leak source on NA/NB Miatas; it typically fails before the valve-cover gasket. The oil runs down onto the nearby heater hoses (which it can rot) and the bellhousing. It is a nuisance leak rather than a failure, but a badly heat-soaked or oil-fouled CAS can also contribute to intermittent driveability faults.

    Common Symptoms

    • Oil weep/drip at the rear of the cylinder head
    • Oil-soaked heater hoses near the firewall
    • Burning oil smell
    • Occasional heat-soak stall or hard restart when hot (severe cases)

    How to Fix

    Remove the CAS, discard the old O-ring, and install a fresh O-ring (a Viton -222 size is commonly used) lightly lubricated with clean oil; reindex the CAS to its factory alignment on reinstall so ignition timing is preserved. The part is a few dollars; most owners do it themselves. A shop visit is inexpensive. If a heat-soaked sensor is causing driveability faults, replace the CAS unit itself.

    Typical repair cost:$80 - $300

    Research This Issue

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    High ConfidenceVerifiedReviewed Jul 2026

    On the 1990-2008 Mazda MX-5 Miata, 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. Cars fitted with high-clamp aftermarket pressure plates fail sooner because of the higher pedal pressure, and owners repeatedly report cheap non-Mazda replacement cylinders lasting under a year. The ND uses a different, largely plastic-bodied slave (N251-41-920) that owners also criticize for durability.

    Common Symptoms

    • Clutch pedal goes to the floor and stays down
    • Cannot select gears with the engine running
    • Pedal feels progressively softer over weeks
    • Fluid loss from the clutch reservoir with no visible brake leak
    • Wet fluid behind the slave cylinder rubber boot

    How to Fix

    Diagnose by pulling back the slave cylinder's rubber boot: wet fluid there condemns the unit. Replace with a genuine Mazda slave cylinder rather than a budget parts-store unit, and inspect the flexible clutch line at the same time. Bleed the system thoroughly - the slave traps air, so gravity-bleed or reverse-bleed if the pedal stays soft. If the master cylinder is also weeping at the firewall pushrod, replace both together and flush the fluid, since contaminated old fluid attacks the seals.

    Typical repair cost:$60 - $400

    Research This Issue

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    Low ConfidenceVerifiedReviewed Aug 2026

    On the 1990-1999 Mazda MX-5 Miata, 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, rotting it from the inside out even when exterior paint looks fine. NB (1999+) frame rails are double-layer ('tinfoil sandwich') and rust worse than the single-layer NA rails. Salt-belt/winter cars are worst, but even garage-kept examples show rear-rocker rot. Because the rockers are structural on these unibody roadsters, advanced rot compromises chassis rigidity and safety.

    Common Symptoms

    • Bubbling paint at the rear of the rocker panels
    • Flaking/perforated metal behind the front tires
    • Rust flakes visible in the sill drain holes
    • Soft/crunchy metal when probed at rockers or frame rails
    • Reduced chassis rigidity / cowl shake

    How to Fix

    Inspect carefully during purchase (probe the rear rockers and frame rails, don't just look). Small surface rust can be treated and sealed. Perforated rockers/frame rails require cutting out the rot and welding in replacement panels or reproduction rocker/rail sections (OEM NA single-layer rails preferred over NB double-layer). Add drain holes and cavity wax as prevention. Budget varies widely by severity and per side.

    Typical repair cost:$500 - $4,000

    Research This Issue

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    Community Reported
    High ConfidenceVerifiedReviewed Jul 2026
    Community reported
    5,000 owners

    On the 1990-2025 Mazda MX-5 Miata, 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 reduced visibility. Expected soft top life is 7-10 years with proper care.

    Common Symptoms

    • Visible cracks or tears in top material
    • Rear window yellowing, hazing, or separating from fabric
    • Water leaks into cabin during rain
    • Top material shrinking and pulling away from frame
    • Difficulty latching top due to shrinkage

    How to Fix

    Replace soft top assembly. OEM replacement is available but aftermarket options (Robbins, TwinTop) offer better materials at lower cost. For NA/NB, replace rear window at same time. Apply 303 Aerospace Protectant or RaggTopp UV treatment every 3-6 months to maximize top life.

    Owner tips & cautions

    • TipNever fold the top with a cold/stiff rear window (NA/NB) - causes permanent creases and cracks
    • TipDIY soft top replacement is doable in a weekend with Miata.net installation guide
    Typical repair cost:$300 - $1,500

    Research This Issue

    Based on 5,000 owner reports

    GoogleRedditYouTubeNHTSA
    Community Reported
    High ConfidenceVerified5,000 owner reportsLast reported by owners Nov 2024Reviewed Feb 2026

    On the 1990-1999 Mazda MX-5 Miata, 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 zipper stitching tears out where the window meets the top. This is a near-universal age issue on unrestored cars and badly hurts rear visibility. A glass rear window with defroster was optional/standard on some later NB tops and does not haze, but zipper-window NA tops are the common case in this era.

    Common Symptoms

    • Cloudy, yellowed, or opaque rear window
    • Cracks or splits in the plastic window
    • Window separating/tearing from the top at the zipper seam
    • Poor rearward visibility

    How to Fix

    Options scale with budget: DIY replace just the vinyl window panel for the lowest cost; have an upholstery shop transplant a new rear window (~$200-300 typical); or replace the entire soft top with a modern top that has a glass window and defroster. Note that aftermarket replacement windows use a non-standard zipper that will not mesh with the original Mazda zipper, so the original zipper often must be transferred to the new panel.

    Typical repair cost:$100 - $700

    Research This Issue

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    Community Reported
    High ConfidenceVerifiedReviewed Jul 2026

    On the 1990-1997 Mazda MX-5 Miata, the NA's retractable headlights are driven by two independent retractor motors, each containing a limit-switch assembly of three spring contacts riding on printed traces plus a set of diodes under a white plastic cover. Grease dries and the contacts and traces wear, so one light hunts up and down repeatedly before parking, stalls half-raised, or drops while driving. The shared 30A headlight relay and its fuse are the other common single point of failure, and a popped cap at the motor-to-linkage connection lets a lamp fall on its own.

    Common Symptoms

    • One headlight winks up and down several times before parking
    • Headlight stuck half up or fully up
    • Headlight drops closed while driving
    • Neither headlight raises (relay or fuse)
    • Grinding or straining noise from the retractor

    How to Fix

    Confirm the fault side by swapping the suspect motor onto the other side. Check the 30A retractor relay and fuse first - a bad relay mimics a dead motor on both sides. If the motor is at fault, open the housing, clean the three spring contacts and the copper traces, inspect the diodes under the white cover, and repack the gears with fresh grease; this restores most units. Replace the retractor motor only if the traces are worn through. Re-seat and secure the linkage cap so the lamp cannot drop.

    Typical repair cost:$40 - $400

    Research This Issue

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    Community Reported
    Medium ConfidenceVerifiedReviewed Aug 2026

    On the 1994-2000 Mazda MX-5 Miata, 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 ON position with the engine not running - the igniter transistor overheats and either burns out or melts its own solder connections. The result is a dead cylinder pair, a persistent misfire, and unburned fuel dumped into the catalytic converter.

    Common Symptoms

    • Hesitation or stumble on startup that worsens over time
    • Severe misfire under load
    • Running rich, fuel smell, black smoke
    • Check engine light with misfire codes
    • Dead cylinder pair (1&4 or 2&3)

    How to Fix

    Replace the coil pack with an OEM Mazda unit (owners repeatedly report short life from budget aftermarket coils). Replace the plug wires and spark plugs at the same time since a failing coil stresses them, and inspect the catalytic converter if the car was driven while misfiring. Avoid leaving the key in ON without the engine running.

    Typical repair cost:$90 - $350

    Research This Issue

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    Medium ConfidenceVerifiedReviewed Aug 2026

    On the 1990-1999 Mazda MX-5 Miata, 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 the car. The water pump is driven behind the timing belt and commonly weeps or fails in the same 70k-170k window, so it is standard practice to replace the pump, tensioner, and seals while the belt is off since ~90% of the labor overlaps.

    Common Symptoms

    • Engine cranks but will not start (belt failed)
    • Coolant weeping from the timing cover / under the crank pulley (water pump)
    • Ticking or squeal from the timing cover
    • Overheating from failed water pump
    • Cracked, glazed, or contaminated timing belt on inspection

    How to Fix

    Replace the timing belt on a strict time/mileage interval (every ~60k miles or when age/condition warrants) and do the water pump, tensioner spring, idler, front crank/cam seals, and accessory belts at the same time. Verify cam and crank timing marks on reassembly. DIY kits are affordable; shop labor is moderate.

    What you need to fix it

    Only diagnosis- and fitment-reviewed repair parts are linked here.

    • Treasure Coast Miata 1990-1993 premium Gates/Mazda timing-belt and water-pump kit
      OEMTreasure Coast Miata 14385851 / TCM-0455

      Complete timing-belt and water-pump service kit for the 1990-1993 1.6L branch Fitment/availability: The inspected direct page identifies SKU 14385851 for 1990-1993 Miata, requires selection around VIN 209445 and showed $271.50 with Add t…

      Treasure Coast Miata
    • Treasure Coast Miata 1994-2000 premium Gates/Mazda timing-belt and water-pump kit
      OEMTreasure Coast Miata 18598700 / TCM-0519

      Complete timing-belt and water-pump service kit for the corrected 1994-1997 and 1999 1.8L branches Fitment/availability: The inspected direct page identifies SKU 18598700 for 1994-2000 Miata, requires a year selection and showed $269.70 …

      Treasure Coast Miata

    As an Amazon Associate, we earn from qualifying purchases; other part links may also earn au7o a commission. Confirm fitment by VIN before buying.

    Typical repair cost:$350 - $900

    Research This Issue

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    Frequently Asked Questions

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

    According to Au7o's analysis of 8,800+ owner reports, the 1994 Mazda MX-5 Miata has 11 documented issues. The most frequently reported are: Clutch Slave Cylinder Piston Seal Leak - Sudden Loss of Clutch Release, Timing Belt and Water Pump Failure (NA 1.6L/1.8L), 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 1994 Mazda MX-5 Miata has 11 known issues documented across 8,800+ owner reports. 3 issues are rated critical: Clutch Slave Cylinder Piston Seal Leak - Sudden Loss of Clutch Release 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). 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 $40 to $4,000, depending on the specific problem and whether you choose DIY or professional repair. The most critical issue, Clutch Slave Cylinder Piston Seal Leak - Sudden Loss of Clutch Release, typically costs $60-$400 to repair. Au7o provides step-by-step DIY maintenance guides that can help reduce repair costs.

    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 1990-1997 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 1990-2025 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 1990-1997 Mazda MX-5 Miata NA Pop-Up Headlight Retractor Motor and Relay Failure (Winking / Stuck Headlights)?

    The NA's retractable headlights are driven by two independent retractor motors, each containing a limit-switch assembly of three spring contacts riding on printed traces plus a set of diodes under a white plastic cover. Grease dries and the contacts and traces wear, so one light… Repairs typically run $40-$400. 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 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 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.

    Content on this page was compiled with AI assistance using NHTSA complaints, TSBs, owner reports, and public automotive data. While we strive for accuracy, this information may contain errors. Always verify repair procedures and specifications with your vehicle's service manual or a qualified mechanic.

    Data sourced from 8,800+ owner reports, NHTSA recalls, TSBs, and automotive forums.