Autolite AP5143 Spark Plug

Autolite Platinum Spark Plug AP5143

Autolite Platinum Spark Plug AP5143 is an OE-style replacement built for consistent ignition performance in a wide range of Ford, Mazda, Mercury, and Land Rover applications. It uses platinum on the center electrode for added durability versus standard copper designs, along with a resistor design for stable operation.

Key Features

• Platinum center electrode tip material for longer service life than standard copper plugs
• OE form, fit, and function replacement for factory-style ignition service
• Pre-gapped to 0.054 in. / 1.40 mm for listed applications
• Resistor spark plug with 4000 ohm resistance
• Nickel ground electrode with tapered tip design
• Ceramic extra-long insulator for reliable electrical isolation
• 14.0 mm thread diameter, 5/8 in. hex, and tapered seat design

Product Details

The Autolite Platinum Spark Plug line is built for drivers who want a direct-fit ignition service part that matches OE-style dimensions and performance requirements. AP5143 uses a platinum center electrode and platinum tip material to support easier starting, quicker throttle response, and improved fuel economy compared with standard copper plugs, while maintaining the fitment and terminal style expected in factory ignition systems. This part number is commonly searched as Autolite AP5143 spark plug for Ford Ranger, Ford Explorer, Ford Mustang, Mazda B4000, Mercury Mountaineer, and Land Rover LR3 applications.

This part cross-references Autolite 403 and SKF 6119 for the same application.

What It Helps Address

• Hard starting caused by worn or fouled spark plugs
• Misfire symptoms from weakened ignition output
• Rough idle related to aged secondary ignition components
• Reduced fuel economy from inefficient spark delivery
• Slower acceleration response from degraded plug performance

Installation Notes

Verify the engine-specific gap before installation. Listed fitments call for 0.054 in. / 1.4 mm in many Ford, Mazda, Mercury, and Land Rover applications, while some Escort and Lynx listings specify 0.044 in. / 1.1 mm. Confirm thread diameter, reach, seat type, and terminal style against the vehicle service information before tightening. AP5143 is listed for vehicles including 2004-2005 Ford Ranger, 2006-2010 Ford Mustang, 2006-2010 Mercury Mountaineer, 2006-2010 Ford Explorer, 2007-2010 Ford Explorer Sport Trac, 2008-2010 Mazda B4000, and 2005-2008 Land Rover LR3.

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

Quality Assurance

Autolite supplies ignition products for aftermarket and original equipment use, and this Platinum Spark Plug line is built to OE-style specifications for form, fit, and function. AP5143 is engineered with platinum electrode materials and standard terminal and seat dimensions to support dependable service in the listed applications.