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Bosch indicates the heat range in the middle of the plug number. For example, FR6DC+ has a heat range of 6. Bosch plugs get hotter the higher the number, colder the lower the number.
Starting with part # FR6DC+ (heat range 6), a colder plug would be # FR5DC+ (heat range 5), a hotter plug would be # FR7DC+ (heat range 7).
Once you have decided on a number, test to see if it exists by typing it into the search box. If it exists, you can add the part to your cart. For additional assistance contact our tech team at 888-800-9629.