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BOSCH 4309 Specifications
Center Electrode Core MaterialPlatinum
Center Electrode Tip MaterialPlatinum
Gap Size1.6 mm
Ground Electrode Quantity2
Ground Electrode Tip MaterialNickel-Yttrium
Hex Size16
Insulator MaterialCeramic
Manufacturer Heat Range9
Reach19 mm
Resistance6000
Seat TypeTapered
Short StyleNo
Thread Diameter14 MM
PLATINUM+2; Pre-Set Gap: 0.063"
Two ground electrodes and more platinum than Bosch Platinum Plus for optimum engine performance and longer life.

Features & Benefits:
  • Revolutionary firing technology featuring multiple spark paths to deliver a longer, more powerful spark for optimum engine performance
  • More platinum vs. Bosch Platinum Plus for smoother acceleration, better gas mileage and optimum engine performance
  • Two yttrium-enhanced ground electrodes provide optimum access to the air/fuel mixture for more efficient combustion...plus a longer performance life
  • Factory pre-set gap for ease of installation. Never requires adjustment
Which BOSCH Spark Plug Is Right For You?

Material / Series Lifespan / Durability Performance / Ignitability Efficiency / Fuel Economy
Copper / Nickel
Copper
★★
Platinum
Platinum
★★★★ ★★★★ ★★
Double Platinum
Double Platinum
★★★★★ ★★★ ★★
Iridium
Iridium
★★★★★★ ★★★★★ ★★★
Double Iridium
Double Iridium
★★★★★★★ ★★★★★ ★★★
Double Iridium Pin-to-Pin
Double Iridium Pin-To-Pin
★★★★★★★ ★★★★ ★★★
Bosch OE-Fine Wire Performance Guarantee

Bosch guarantees you will feel improved performance in your vehicle when using any of Bosch OE Fine Wire Spark Plugs (Double Iridium, Double Iridium Pin-to-Pin, Double Platinum and Platinum). However, if you do not experience quicker starts, smoother acceleration and improved fuel efficiency, you can return the plugs with a dated sales receipt and Bosch will refund the purchase price of the spark plugs.

PLATINUM
Offer extends for four (4) years or for the manufacturer’s recommended spark plug change interval as indicated in the owner’s manual -- whichever occurs first.
Learn More
4 YEAR
PERFORMANCE
GUARANTEE
Additional Resources

Diagram of Proper Torquing
Spark Plug Condition Identification
Spark Plug Gap Illustrations
Spark Plug Temperature Curves-Heat Range

Warranty Information:
12 Months Satisfaction Guarantee for Double Iridium, Double Platinum, and Platinum Spark Plugs Only
Warranty Details