Genuine Mazda Ignition HT Lead Set – MX-5 Mk2 1.6 • B6MC-18-140B

Genuine Mazda B6MC-18-140B Ignition HT Lead Set

Replacement Genuine Mazda high-tension ignition lead set for Mazda MX-5 Mk2 and Mk2.5 / NB models with the 1.6L petrol engine listed in the compatibility table.

The four insulated leads connect the twin ignition-coil assembly to the engine spark plugs, carrying the high-voltage electrical pulse required to ignite the air-and-fuel mixture inside each cylinder.

Correctly functioning ignition leads help maintain reliable starting, stable idle, clean acceleration and consistent combustion under engine load.

Age, heat and repeated vibration can cause the insulation, internal conductor or terminal connections to deteriorate. High voltage may then leak to the engine or adjacent components instead of reaching the spark plug.

This listing supplies one complete Genuine Mazda four-piece ignition lead set, which is the quantity required per applicable engine.

• Part type: High-tension ignition lead set
• Mazda catalogue description: Cord set, high tension
• Alternative descriptions: HT leads / spark-plug leads / ignition cable set / plug-wire set
• Mazda diagram position: 18140
• Primary function: Transfers high-voltage ignition current from the coils to the spark plugs
• System: Engine ignition system
• Fitting position: Between the ignition-coil assembly and spark plugs
• Primary vehicle application: Mazda MX-5 Mk2 and Mk2.5 / NB 1.6L
• Engine application: 1.6L B6-family petrol engine
• Transmission application: Manual
• Number of leads: Four
• Quantity required per engine: One complete set
• Quantity supplied: Four ignition leads
• Brand: Genuine Mazda
• Part No.: B6MC-18-140B
• Also referenced as: B6MC18140B
• Associated earlier revision: B6MC-18-140A

Typical reasons for replacement:

• Intermittent or persistent engine misfire
• Rough or unstable idle
• Difficult starting
• Hesitation during acceleration
• Misfire under heavy engine load
• Reduced performance or increased fuel consumption
• Visible cracking or hardening of the insulation
• Burn marks or evidence of electrical arcing
• Loose, corroded or damaged terminals
• Unknown ignition-lead age or service history

Fitment advice: This listing is conservatively allocated to the Mazda MX-5 Mk2 and Mk2.5 / NB 1.6L engine application associated with the B6MC Mazda reference. Similar-looking lead sets and related Mazda numbers are used on other NA and NB engines.

Reference advice: Aftermarket catalogues commonly group B6MC-18-140B with B61P-18-140B, B61P-18-140C, BPE8-18-140 and BPE8-18-140A. These references should not automatically be treated as a confirmed one-directional Mazda supersession chain.

Replacement advice: Replace the leads as a complete set to maintain consistent conductor resistance, insulation condition and terminal fit across all four cylinders.

Routing advice: Record the original firing-order and lead routing before removal. Replace one lead at a time where possible to avoid connecting the ignition coils to the wrong cylinders.

Removal advice: Pull each lead using the moulded terminal boot rather than the cable itself. Pulling directly on the cable can separate the internal conductor from the terminal.

Inspection advice: Inspect the ignition coils, coil towers, spark-plug wells and lead-separating clips. Oil, water, corrosion or carbon tracking can cause repeated misfires even after new leads are installed.

Spark-plug advice: Inspect the spark plugs for wear, contamination, incorrect gap or cracked insulation. Excessive spark-plug resistance can place additional electrical stress on the ignition leads and coils.

Oil-leak advice: Engine oil inside the spark-plug wells usually indicates deterioration of the rocker-cover or plug-well seals. Repair the leak before fitting the replacement leads.

Diagnostic advice: Ignition-lead failure is only one possible cause of a misfire. Check the spark plugs, ignition coils, electrical connections, compression and fuel delivery where symptoms remain after replacement.

Other items to consider: Consider inspecting or replacing the spark plugs, ignition coils, rocker-cover gasket, plug-well seals and ignition-lead retaining clips according to their condition.

Useful tools / consumables: Spark-plug socket, ratchet and extension, torque wrench, dielectric grease used sparingly where appropriate, inspection lamp and electrical-contact cleaner.

Difficulty guide: DIY Difficulty: Easy. The leads are accessible from the top of the engine, but the correct firing order and original routing must be maintained.

Why Genuine Mazda? Genuine Mazda ignition leads are manufactured to the intended lengths, conductor resistance, terminal design, insulation specification and original engine routing. Using the correct OE set helps ensure secure connections at the ignition coils and spark plugs.

What’s in the box: One Genuine Mazda four-piece high-tension ignition lead set, part number B6MC-18-140B. Ignition coils, spark plugs, retaining clips and installation tools are not included unless specifically shown or stated separately.

Installation notes: Switch off the ignition and allow the engine to cool. Record the original lead positions and routing, then replace one lead at a time. Push each terminal fully onto its ignition-coil tower and spark plug until securely seated. Route the cables through the original clips, keeping them away from hot, sharp or moving components, and confirm the firing order before starting the engine.