Autolite XP5143 Spark Plug

Autolite Iridium XP Spark Plug XP5143

Autolite XP5143 is an iridium spark plug built for performance-focused ignition service. It uses an iridium fine-wire center electrode, a platinum ground electrode, and a tapered ground wire to support efficient combustion, steady ignitability, and responsive engine operation.

Compatible With Ford Ranger, Ford Explorer, Ford Explorer Sport Trac, Ford Mustang, Mazda B4000, Mercury Mountaineer, Land Rover LR3, Ford Escort, and Mercury Lynx applications listed below.

Key Features

• Iridium center electrode with fine-wire design for durable spark delivery
• Platinum ground electrode tip for added wear resistance
• Taper-cut ground electrode design to help improve engine efficiency
• Pre-gapped at 0.054 in. / 1.4 mm
• Resistor spark plug with 4,000 ohms resistance
• Ceramic insulator and copper core center electrode construction
• M14 x 1.25 thread, 5/8 in. hex, tapered seat
• Long projection design with a non-removable nut terminal

Product Details

The Autolite Iridium XP line is built around a fine-wire iridium center electrode paired with a proprietary platinum ground electrode. That combination is used to maintain spark consistency while reducing electrode wear over time. XP5143 also features a tapered ground wire and long projection configuration, making it a direct-fit ignition service part for select Ford, Mazda, Mercury, and Land Rover engines. This part number, XP5143, is commonly searched for Ford Ranger spark plug replacement, Ford Mustang iridium spark plug service, and Ford Explorer ignition tune-up applications.

This part cross-references Anchor 9616 for the same application.

Common Issues This Part Can Address

• Rough idle caused by worn spark plug electrodes
• Hard starting from weak or inconsistent ignition output
• Reduced throttle response during acceleration
• Fuel economy loss related to degraded spark performance
• Misfire conditions tied to aged plugs in high-mileage engines

Installation Notes and Tips

Verify thread size, seat type, and pre-gap before installation. XP5143 uses a tapered seat and a pre-gap of 0.054 in. / 1.4 mm, so confirm the engine specification matches the plug before service. Use proper spark plug socket tools and follow the vehicle manufacturer’s torque procedure. For fitment verification, this plug is listed for 2004-2005 Ford Ranger, 2005-2010 Ford Mustang, 2006-2010 Ford Explorer, 2007-2010 Ford Explorer Sport Trac, 2006-2010 Mercury Mountaineer, 2008-2010 Mazda B4000, 2005-2007 Land Rover LR3, 2008 Land Rover LR3, 1987-1990 Ford Escort, and 1987 Mercury Lynx.

• Fits 2004-2005 Ford Ranger, N/A
• Fits 2009-2011 Ford Ranger, N/A
• Fits 2005-2010 Ford Mustang, N/A
• Fits 2006-2010 Ford Explorer, N/A
• Fits 2007-2010 Ford Explorer Sport Trac, N/A
• Fits 2006-2010 Mercury Mountaineer, N/A
• Fits 2008-2010 Mazda B4000, N/A
• Fits 2005-2007 Land Rover LR3, N/A
• Fits 2008 Land Rover LR3, N/A
• Fits 1987-1990 Ford Escort, N/A
• Fits 1987 Mercury Lynx, N/A

Quality Assurance

Autolite designs the Iridium XP series for durability-focused ignition service, using iridium and platinum electrode materials to support long-term spark stability and efficient engine operation. XP5143 is built to the listed specifications for direct replacement use in the confirmed applications above.