Bosch 7909 spark plug for the 1985-1993 BMW 535i 6-cylinder 3.5L and other vehicles ignites the air-fuel mixture in the cylinder. Its heavy-duty yttrium-enhanced nickel-copper center electrode gives up to 50% longer performance life than standard copper plugs.
A worn plug can show up as misfires, hard starting or a rough idle. These signs alone do not prove the plug is the problem, since a weak ignition coil can cause a misfire too.
The 1985-1993 BMW 535i 6-cylinder 3.5L, the 1985-1992 BMW 735i 6-cylinder 3.5L and the 1988-1992 BMW 735iL 6-cylinder 3.5L all take these Bosch BMW spark plugs, as do many other BMW models. The 1985-1993 BMW 535i 6-cylinder 3.5L takes six. For a BMW not named here, find its year and engine in the "Vehicles it fits" section.
Fit and size
Build and materials
One spark plug.
Is this a BMW 535i spark plug for the 1985-1993 model with the 6-cylinder 3.5L?
Yes. The Bosch 7909 fits the 1985-1993 BMW 535i 6-cylinder 3.5L, and that car takes six plugs.
Do Bosch plugs like the 7909 need anti-seize on the threads?
No. The nickel-plated rolled threads on the Bosch 7909 do not require anti-seize, which saves installation time.
Does the Bosch 7909 have a built-in resistor?
Yes. The Bosch 7909 has a metal glass fused resistor for interference suppression.
What does the copper core in this spark plug do?
The copper core gives this spark plug a broader heat range, which helps it resist pre-ignition and fouling.
How does the insulator on the Bosch 7909 help against misfires?
The insulator is angled and ribbed, a design intended to prevent misfire caused by flash-over.
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WARNING: These products can expose you to chemicals including lead and phthalates, which are known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov.
