Common issue on Mercedes vehicles nowadays, Adblue and Nox sensor problems causing limp home mode and engine light on, plus also it shows the red signal on the Adblue quantity on the dash. An expensive mistake would be to go back to Mercedes for them to reset this, usually down to an overfull Adblue tank and a reset of the ECU to compensate, once done everything is back to normal operation and all for £149inc! That's an hourly rate at Mercedes now! https://Remap-UK.co.uk contact us if you need help with your Adblue issues.