Mercedes GLA power loss issue

I had a similar experience with my GLA, with reduced power and the check engine light. It could be the throttle sensor or throttle body affecting engine air flow. Is the car idling rough, or is there anything else unusual besides the power loss? Cleaning the throttle body can sometimes help, but replacement is often the only real fix. Have you checked for air leaks in the intake system? That can cause similar symptoms.

It's not idling rough, it's been pretty stable. I haven't checked for air leaks, I wouldn't know where to start. Was it the throttle sensor in your case? What was the repair cost?

No rough idling rules out a few things. Unless you're familiar with engine components, it’s best to leave checking for air leaks to a professional. In my case, the throttle body needed replacement. The diagnostic pointed to a faulty throttle sensor, but they recommended replacing the whole throttle body. I suggest getting a proper diagnosis at a workshop. They can pinpoint the exact problem and give you a precise quote. It's better than guessing. Modern cars are complex.

Thanks, that's solid advice. The shop confirmed it was the throttle valve. The replacement cost me about 265€, which is reasonable. The car runs like new now.