Autolite 5125 Spark Plug

Autolite 5125 Copper Resistor Spark Plug

Autolite 5125 is a copper resistor spark plug built for OE-style fit, form, and function in a range of Ford truck and van applications. It is specified with a 0.044 in. (1.10 mm) pre-gap and a tapered seat for straightforward replacement service.

The Autolite Copper Resistor Spark Plug line focuses on quick starts, steady acceleration, and fuel-efficient operation in everyday driving. For owners searching for a Ford F-150 spark plug, Ford Bronco spark plug, or Ford Econoline spark plug replacement, part number 5125 provides a direct-service option with the dimensions and terminal style expected in many factory ignition setups.

Key Features

• Copper core center electrode for reliable ignition response
• Resistor design with 4,000 ohms resistance
• Nickel center and ground electrode tip materials
• Tapered ground electrode tip design and tapered seat type
• Extra-long ceramic insulator for secondary ignition service
• Pre-gapped to 0.044 in. / 1.10 mm
• Stud electrical terminal type
• 13/16 in. hex size, 18 mm thread diameter, 0.540 in. reach

Product Details

Autolite 5125 is engineered as an OE-style spark plug replacement for gasoline engines that call for a tapered-seat, resistor-type plug with a 0.044 inch gap. The copper center electrode supports consistent spark delivery, while the nickel electrode tips and ceramic insulator help maintain stable operation in secondary ignition systems. This part number is a practical choice for routine tune-up service on Ford F-150, Ford Bronco, and Ford Econoline applications where the listed specifications match the original equipment requirements.

This part cross-references AMS Automotive 4652 and Carlson 7538 for the same application.

Used For

• Hard starting caused by worn or fouled spark plugs
• Rough idle from weak or inconsistent spark output
• Misfire conditions tied to aged ignition components
• Reduced throttle response during acceleration
• Maintenance replacement on Ford truck and van ignition systems

Installation Notes

Verify the engine’s required plug specification before installation. Autolite 5125 uses a 0.044 inch (1.1 mm) gap, tapered seat, 13/16 inch hex, and stud terminal, so the replacement should match the vehicle’s original ignition requirements. Check the gap during service and confirm the plug reaches the correct depth for the cylinder head application. Fits 1987-1996 Ford F-150, N/A. Fits 1987-1992 Ford Bronco, N/A. Fits 1987-1995 Ford E-150 Econoline, N/A. Fits 1987-1995 Ford E-150 Econoline Club Wagon, N/A. Fits 1987-1995 Ford E-250 Econoline, N/A. Fits 1987-1995 Ford E-350 Econoline, N/A. Fits 1987-1995 Ford E-350 Econoline Club Wagon, N/A. Fits 1987-1995 Ford F-250, N/A. Fits 1987-1995 Ford F-350, N/A. Fits 1987-1991 Ford E-250 Econoline Club Wagon, N/A. Fits 1996 Ford E-150 Econoline, N/A. Fits 1996 Ford E-150 Econoline Club Wagon, N/A. Fits 1996 Ford E-250 Econoline, N/A. Fits 1996 Ford E-350 Econoline, N/A. Fits 1996 Ford E-350 Econoline Club Wagon, N/A. Fits 1996 Ford F-250, N/A. Fits 1996 Ford F-350, N/A.

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 the listed Ford applications. Part number 5125 is manufactured to support dependable secondary ignition service in vehicles that require the stated plug design and gap.