Exhaust
What is an Oxygen (O2) Sensor?
Measures leftover oxygen in the exhaust so the ECU can fine-tune the fuel mixture.
Simplified animation — not to scale.
In plain English
Threaded into the exhaust header, the oxygen sensor constantly reports how much unburnt oxygen is left in the exhaust gas, letting the ECU correct the fuel mixture in real time.
A simple analogy
“A taste-tester for the exhaust, reporting back so the chef, the ECU, can adjust the recipe on the fly.”
How it works
A chemical reaction inside the sensor generates a small voltage proportional to the oxygen level in the exhaust stream. The ECU reads this continuously and leans or richens the fuel mixture to keep combustion as clean and efficient as possible.
Signs of trouble
- ⚠Poor fuel economy
- ⚠Rough idle
- ⚠Engine management light with an O2 sensor code
- ⚠Failing an emissions-related MOT check
Rough UK cost
£60–£220
Parts: £40–£180
Labour: £20–£60
Always get a written quote. Prices vary by bike, region, and parts brand.
Heads up: Motoautonomy is for general guidance only. If your bike is showing warning lights or behaving oddly, get it looked at by a qualified mechanic.