Bosch 8501 Spark Plug

Bosch EVO 8501 Spark Plug Overview

The Bosch EVO 8501 spark plug is built for modern gasoline engines that demand stable ignition under high cylinder pressure and elevated heat. It uses an iridium center electrode, a projected ceramic insulator, and a 45 kV+ dielectric design to maintain reliable spark performance in turbocharged and direct-injection applications.

Compatible With select Audi, Volkswagen, and Porsche models, this Bosch EVO spark plug is engineered for OE-level fit and consistent combustion control. It is a direct replacement choice for drivers servicing Audi A3, A4, Q5, RS3, Volkswagen GTI, Jetta, Tiguan, and related applications.

Key Features

• Bosch EVO line engineered for modern engine ignition demands
• Part number 8501 for accurate ordering and service matching
• Iridium center electrode tip for durable spark delivery
• Platinum and nickel-chromium-iron/copper ground tip materials
• 1000 ohm resistor design for ignition system stability
• Projected ceramic insulator for controlled combustion exposure
• Standard ground electrode configuration with 0.65 pre-gap
• 14 mm thread diameter, 26.5 mm reach, and 16 mm hex size

Product Details

Bosch EVO is the brand line developed for demanding late-model engines, especially turbocharged gasoline direct injection platforms that place greater stress on spark plugs. The Bosch 8501 uses a flat seat, standard ground electrode layout, and a heat range of 5 to support consistent ignition characteristics in applications that require precise spark control. Bosch builds the EVO series to OE-quality standards, and the design focuses on resisting irregular combustion events found in advanced engine calibrations.

Fits 2015-2025 Volkswagen GTI, N/A; Fits 2013-2019 Volkswagen Jetta, N/A; Fits 2018-2024 Audi A5 Quattro, N/A; Fits 2018-2025 Audi Q5, N/A; Fits 2017-2025 Audi Q7, N/A; Fits 2017-2021 Porsche Macan, N/A. Part number 8501 is also listed for additional Audi A3, A4, A6, RS3, TT, TTS, and Volkswagen Atlas, Tiguan, Passat, and Golf applications shown in the fitment data.

Common Issues This Part Addresses

• Misfire caused by worn or heat-stressed spark plugs
• Hard starting from weak or inconsistent ignition output
• Rough idle in turbocharged gasoline engines
• Loss of throttle response from degraded spark quality
• Combustion instability in high-load or high-boost operation

Installation Notes and Tips

Verify the engine code and OE plug specification before installation, especially on Audi and Volkswagen turbocharged applications. Check the gap against the vehicle service information before use, and inspect coil boots, ignition coils, and plug wells for contamination or wear while servicing the plugs. Use the correct torque procedure for the flat-seat design to help maintain proper sealing and thread integrity.

Quality Assurance

Bosch develops and manufactures the EVO series to the same quality expectations associated with original equipment applications. The 8501 is built for dependable ignition performance in modern engines that place higher electrical and thermal demands on the spark plug.