HELLA spark plug (8EH 188 704-421) 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]: Steel, 0 mm, Thread Size: M14 x 1.25, Spanner Size: Silicone, Tightening Torque [Nm]: 28 Nm — 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 AUDI, SKODA, VW cylinder heads without re-gapping or thread chasing. Replaces OE ignition references: 0 242 229 654, 0 242 229 798, 0 242 229 799, 0 242 229 878 and 11 more. HELLA 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 from our UK warehouse with a 30-day money-back guarantee and free hassle-free returns.

HELLA, founded in 1899 in Lippstadt, Germany, is a global automotive lighting and electronics specialist now operating as FORVIA HELLA. HELLA specialises in headlamps, rear lights, signal lighting, sensors, actuators, and electronic control units. As an OE supplier to virtually all major car manufacturers, HELLA products represent the cutting edge of automotive lighting and electronic technology. With 125+ years of innovation in vehicle illumination and electronics, HELLA is the definitive choice for high-quality lighting and electronic component replacements.