Error 41 may occur when you press and hold the turbo boost button for a long time, or when you press it too many times in a row. It can also occur if water gets into the button. 

Try these steps to fix it. 

1. Make sure your bike has the latest firmware installed – you can check this on your app settings screen. If there is a new version available, install it. 
2. Press and hold the power button on the underside of the top tube for two seconds until you see the reset symbol on the Matrix Display. Your bike will now restart. Press either handlebar button to power the bike on. If the bike is locked, use one of the 3 ways to unlock your bike.

3. If this doesn’t work, the button might be stuck. Try pressing and holding the Turbo Boost button while the bike is unlocked and standing still. You should see the power levels changing on the Matrix Display.