Autolite 103 Spark Plug

Autolite 103 Copper Resistor Spark Plug

Autolite 103 is a copper resistor spark plug built for OE-style fit, form, and function across a wide range of Ford, Mercury, Lincoln, Jaguar, Mazda, Cadillac, Audi, Volvo, Mercedes-Benz, Dodge, and Pontiac applications. It is a practical replacement choice for drivers looking for reliable starting, steady idle quality, and smooth throttle response.

Key Features

• Copper center electrode core for dependable ignition performance
• Nickel center and ground electrode tip materials
• Resistor design for reduced electrical noise
• Tapered ground electrode tip design
• Ceramic insulator with mid-projection design
• 0.050 in. pre-gap size, 14.0 mm thread diameter, 17.0 mm reach
• Stud-style electrical terminal and 5/8 in. hex size

Product Line Details

The Autolite Copper Resistor Spark Plug line is positioned as an OE-style replacement option for everyday service work. Part number 103 follows the original equipment style needed for many late-model and older vehicles, making it a straightforward choice when replacing worn spark plugs on Ford E-350 Super Duty, Ford Ranger, Ford Mustang, and related applications.

Detailed Description

Autolite 103 uses a standard copper core center electrode with nickel tip materials to support consistent spark delivery and dependable combustion. The resistor construction helps control ignition interference, while the tapered seat and mid-projection ceramic insulator support OE-style installation and combustion chamber fitment. This spark plug is listed across 355 vehicle applications, with fitment coverage spanning 1982-2019 model years.

This part cross-references DENSO Auto Parts 5040 for the same application.

What It Helps Address

• Hard starting caused by worn spark plugs
• Rough idle from weak or inconsistent spark
• Reduced throttle response during acceleration
• Misfire symptoms related to aged ignition components
• Ignition noise in resistor-equipped systems

Installation Notes and Tips

• Verify the vehicle-specific gap before installation; listed applications include 0.044 in., 0.050 in., 0.051 in., 0.052 in., 0.054 in., 0.028 in., 0.032 in., and 0.035 in. requirements depending on model and year.
• Confirm the tapered seat, 14.0 mm thread diameter, 17.0 mm reach, and stud terminal match the engine specification.
• Use the exact fitment notes for your vehicle, especially on Ford E-Series, Ranger, Explorer, Mustang, Fusion, and related models.
• Check service intervals and inspect ignition wires or coils during spark plug replacement.

Quality Assurance

Autolite supplies ignition products to the automotive aftermarket and original equipment manufacturers, and this spark plug is built to OE-style specifications for broad vehicle coverage and consistent service replacement.

• Fits 1999-2019 Ford E-350 Super Duty, N/A
• Fits 2003-2014 Ford E-150, N/A
• Fits 2003-2014 Ford E-250, N/A
• Fits 2007-2012 Ford Escape, N/A
• Fits 2010-2012 Ford Fusion, N/A
• Fits 2007-2012 Ford Mustang, N/A
• Fits 1997-2004 Ford Expedition, N/A
• Fits 1997-2004 Ford Explorer, N/A
• Fits 1997-2003 Ford F-150, N/A
• Fits 2005-2008 Mazda 6, N/A
• Fits 2006-2009 Cadillac STS, N/A
• Fits 2003-2008 Jaguar X-Type, N/A
• Fits 1986-1988 Mercedes-Benz 190E, N/A