NGK Racing Spark Plug R0373A-10 (Stock 4940)
This NGK racing plug is built for engines that run hard and hot. The cold heat range helps control combustion temperatures under high load, high boost, or high compression. It delivers a strong, stable spark for consistent power and reliability on track or fast road.
Use this plug when tuning pushes cylinder temperatures up. It can reduce knock risk and help protect against pre-ignition. For lightly tuned or stock engines, a warmer plug may be more suitable.
- Cold heat range for demanding setups and sustained high RPM
- Resistor design to reduce electrical noise that can affect sensors and ECUs
- Durable construction for consistent spark under pressure
| Part Number | R0373A-10 |
| NGK Stock Number | 4940 |
| GTIN | 087295149409 |
| Category | 686 – Spark Plug |
| Series | NGK Racing |
| Heat Range | 10 (cold – NGK scale) |
| Resistor | Yes |
Fitment guidance
This racing plug suits performance-focussed builds that require a colder heat range. Fitment varies by engine. Use the vehicle lookup on our site or check the Vehicle Fitment tab to confirm compatibility.
Important: Always set the spark plug gap and specification to your engine builder or tuner’s recommendation. Running too cold a plug on a lightly loaded engine can cause fouling.
The price displayed is for a single plug, please add the desired amount to your basket.


