Denso 3015 Spark Plug

Denso 3015 U-Groove Spark Plug Overview

The Denso 3015 is a conventional spark plug built for steady ignition performance in older Cadillac applications. Its U-Groove ground electrode design helps improve ignitability, supporting more efficient combustion in the engine.

Compatible With Cadillac Fleetwood, DeVille, Eldorado, Seville, and Commercial Chassis applications from 1974 through 1984, this plug is a direct-fit choice for owners maintaining original-style ignition service. The Denso 3015 is also referenced as W14EXR-U15.

Key Features

• U-Groove ground electrode tip design for improved spark exposure
• 5000 ohm resistor for ignition noise suppression
• Copper center electrode core for reliable heat transfer
• Nickel center and ground electrode tip materials
• Standard ground configuration with a flat seat
• 14 mm thread diameter, 19.00 mm reach, and 20.6 mm hex size
• Manufacturer heat range 14 with a 1.5 pre-gap size

Product Details

Built under Denso’s U-Groove Conventional line, this spark plug focuses on dependable secondary ignition performance for classic Cadillac engines. The U-shaped ground electrode increases the spark path exposure, which can support more consistent ignition in applications where original-style plug design matters. With a copper core center electrode and nickel electrode materials, the Denso 3015 is suited to routine maintenance on vehicles that call for this specification.

This part cross-references DENSO Auto Parts (e.g., W14EXR-U15) for the same application. Search terms such as Denso 3015 spark plug for 1975-1984 Cadillac Fleetwood or Denso 3015 for 1975-1981 Cadillac DeVille can help narrow the correct replacement.

Common Issues This Part Can Address

• Hard starting caused by worn or fouled spark plugs
• Rough idle from inconsistent ignition firing
• Misfire symptoms related to degraded plug electrodes
• Reduced fuel efficiency from weak spark delivery
• Ignition noise concerns in resistor-equipped systems

Installation Notes and Tips

Verify thread diameter, reach, seat type, and heat range against the vehicle’s service specification before installation. Check the plug gap against the engine requirement, and inspect ignition wires, distributor components, and coil condition at the same time to avoid repeat service. For Cadillac Fleetwood, DeVille, Eldorado, Seville, and Commercial Chassis models, confirm the engine calls for a flat-seat 14 mm plug with a 19.00 mm reach.

Quality Assurance

Denso manufactures this spark plug as part of its conventional ignition lineup, using established electrode materials and a resistor design intended for stable operation in the specified applications. The product details and fitment data support selection for the listed Cadillac models and years.

Compatible Vehicles

• Fits 1975-1984 Cadillac Fleetwood, N/A
• Fits 1976-1981 Cadillac Commercial Chassis, N/A
• Fits 1975-1981 Cadillac DeVille, N/A
• Fits 1980-1981 Cadillac Eldorado, N/A
• Fits 1974-1978 Cadillac Eldorado, N/A
• Fits 1980-1981 Cadillac Seville, N/A