Bosch 7909 Spark Plug

Bosch 7909 Nickel Spark Plug Overview

Bosch 7909 is a conventional nickel-copper spark plug built for steady ignition performance and value. It uses a nickel-ytrium center electrode with a copper core, a projected ceramic insulator, and a resistor design to support reliable spark delivery in older BMW applications.

The Bosch Nickel line focuses on OE-style replacement coverage for vehicles that call for a nickel-copper core spark plug. For BMW 325i, 535i, 735i, and related models, Bosch 7909 provides the correct conventional plug format for factory-style secondary ignition service.

Key Features

• Nickel-ytrium center electrode with copper core for durable spark plug construction
• Resistor design rated at 6000 ohms for ignition noise control
• Projected ceramic insulator for consistent combustion chamber exposure
• Tapered V-profile ground electrode tip for stable spark transfer
• Standard ground configuration with a single ground electrode
• Flat seat, 14 mm thread diameter, and 19 mm reach
• Manufacturer heat range 8 for specified engine applications
• Pre-gapped at .8 mm

Detailed Product Description

Bosch 7909 is a conventional 4-cycle spark plug engineered to meet or exceed original equipment specifications for nickel-copper core spark plugs. Its nickel-ytrium center electrode and copper core are selected to balance service life and ignition performance, while the nickel ground electrode and tapered V-profile tip support consistent spark formation. This part number, Bosch 7909, is a direct-fit style secondary ignition service part for select BMW models including the 325i, 325is, 325iX, 528e, 533i, 535i, 735i, and 635CSi.

This part cross-references Bosch 7509 for the same application.

Common Issues This Spark Plug Can Address

• Hard starting caused by worn or fouled spark plugs
• Rough idle from weak or inconsistent ignition output
• Misfire conditions related to aged secondary ignition components
• Reduced throttle response from degraded spark delivery
• Maintenance replacement for factory-style BMW ignition service

Installation Notes and Tips

Verify the specified gap before installation and compare the plug’s flat seat, 14 mm thread diameter, 19 mm reach, and heat range 8 to the engine requirements. Confirm the application against the vehicle’s service information, especially on BMW models with year-specific notes such as late-production 1988 535i and 1987 528e. Use proper spark plug service procedures to avoid thread damage and ensure correct torque.

Compatible With BMW 325i, 1987-1991; BMW 325is, 1987-1991; BMW 325iX, 1988-1991; BMW 528e, 1982-1988; BMW 533i, 1983-1984; BMW 535i, 1985-1993; BMW 535is, 1988; BMW 635CSi, 1985-1989; BMW 735i, 1985-1992; and BMW 735iL, 1988-1992.

Quality Assurance

Bosch designs the Nickel line as an OE-specification conventional spark plug option for nickel-copper applications. Bosch 7909 is built with a nickel-ytrium and copper center electrode construction and materials selected to support dependable secondary ignition service in the listed BMW fitments.