Autolite APP5503 Spark Plug

Double Platinum Spark Plug Overview

Autolite APP5503 is a Double Platinum spark plug built for OE-style form, fit, and function across a wide range of applications. It uses platinum on both the center and ground electrodes to support consistent firing and longer service life.

Compatible With Saab, Toyota, Honda, Acura, Nissan, Mazda, and other applications listed in the fitment data, this spark plug is a direct replacement choice for drivers looking for stable ignition performance and correct gap specifications.

Key Features

• Double platinum electrode design for durable spark delivery.
• Platinum center and ground electrode tips.
• Resistor construction with a 4000 resistance rating.
• Mid-projection ceramic insulator for controlled combustion chamber exposure.
• Flat seat, 14 mm thread diameter, and 5/8 in. hex size.
• Pre-gapped at 0.044 in. / 1.10 mm for many listed applications.

Detailed Description

Autolite APP5503 is engineered as an OE-style spark plug for secondary ignition service, with platinum-to-platinum firing that helps maintain spark consistency over time. The standard electrode layout, nickel ground core, and ceramic insulator support dependable ignition performance in a broad range of older import and domestic applications. This part number, APP5503, is commonly selected for vehicles that require the specified reach, seat type, and gap configuration. It cross-references Monroe Shocks & Struts (e.g., 172286, 182286) for the same application.

Fitment includes 1984-2005 Saab 900, 9000, 9-3, and 9-2X applications, plus selected Toyota, Honda, Acura, Nissan, and Mazda models. For Saab 9-3, Honda Civic, and Toyota Camry applications, verify the listed gap note before installation. APP5503 is also referenced by buyers searching for a replacement spark plug for Saab 9-3, Honda Civic, or Toyota Camry service.

What It Helps Address

• Hard starting caused by worn spark plug electrodes.
• Rough idle from inconsistent ignition firing.
• Reduced throttle response linked to degraded plugs.
• Fuel economy loss from inefficient spark delivery.
• Misfire concerns when the existing plug no longer holds the correct gap.

Installation Notes and Tips

Confirm the required gap, reach, seat type, and terminal style against the vehicle specification before installation. Some listed applications use different gap settings, so follow the fitment notes for the exact vehicle. Use proper spark plug service procedures and torque to the manufacturer specification for the engine.

Quality Assurance

Autolite supplies ignition products to the automotive aftermarket and original equipment manufacturers, and this Double Platinum line is positioned as an OE-style replacement. APP5503 is built to match the form, fit, and function expected for the listed applications.