FEBI BILSTEIN spark plug (13421) fires the air-fuel charge with a precisely controlled spark at the correct electrode gap and heat range for your engine's combustion chamber geometry. Plug parameters — Electrode Gap [mm]: 0, Ceramic mm, Spanner Size: Silicone, Spark Plug: 37, Spark Plug: 28 — determine ignition timing accuracy, electrode longevity, and resistance to pre-ignition deposits across the full RPM range. Thread reach, seat type, and hex size are specified to fit FIAT cylinder heads without re-gapping or thread chasing. Replaces OE ignition references: 001-10-25990, 001-10-25992, 0046097535, 0 241 240 609 and 219 more. FEBI BILSTEIN ignition components are manufactured to SAE and DIN specifications and are approved for use in vehicles covered by manufacturer service agreements throughout Europe. Standard copper-core spark plugs last around 20,000–30,000 miles, while iridium or platinum-tipped plugs can last 60,000–100,000 miles — always follow the interval specified in your vehicle's service schedule. Symptoms of worn spark plugs include rough idling, engine misfires (often felt as a stumble under acceleration), increased fuel consumption, and difficulty starting in cold weather. Spark plug replacement is a straightforward DIY job on most engines — you need a spark plug socket, a torque wrench, and a gap gauge; allow 30–60 minutes for a four-cylinder engine, longer for boxer or V-configurations where access is tighter. Always match the heat range and electrode material specified by your engine manufacturer — fitting a plug with the wrong heat range can cause pre-ignition, fouling, or catalytic converter damage. Replacing spark plugs on schedule maintains optimal combustion efficiency, reduces harmful emissions, and prevents unburnt fuel from damaging the catalytic converter — a component that costs many times more to replace. Every part is dispatched with tracked delivery and a 14-day money-back guarantee with hassle-free returns.

febi bilstein, founded in 1844 in Ennepetal, Germany, is one of the oldest and most comprehensive automotive parts suppliers in the independent aftermarket. febi bilstein offers over 40,000 parts spanning steering, suspension, engine, braking, cooling, and electrical systems. Certified to IATF 16949 and supplying OE-quality components, febi bilstein products undergo rigorous testing to match original equipment performance. With nearly 180 years of German engineering tradition, febi bilstein is the go-to brand for reliable, competitively priced replacement parts.