What is an ECU (Engine Control Unit)?
The onboard computer that manages fuelling, ignition timing and, on modern bikes, rider aids.
Simplified animation — not to scale.
In plain English
The ECU reads signals from sensors around the engine — throttle position, engine speed, temperature, oxygen content — and uses them to decide exactly how much fuel to inject and when to spark, dozens of times a second.
“The bike's brain, constantly adjusting fuel and spark the way a chef adjusts seasoning, tasting as they go.”
How it works
Sensors feed live data to the ECU, which references pre-programmed maps to calculate the ideal fuel and ignition settings for the current conditions. On modern bikes it also manages traction control, ride modes and quickshifters by talking to the throttle bodies, ignition and gearbox sensors.
Signs of trouble
- ⚠Engine management warning light on the dash
- ⚠Fault codes stored when scanned
- ⚠Erratic idle or stalling
- ⚠Rider aids behaving unpredictably
£150–£700
Always get a written quote. Prices vary by bike, region, and parts brand.