Mercedes GLA Hybrid Engine Problem

I encountered a similar predicament with my GLA. The symptoms you describe the check engine light, diminished engine output, suboptimal engine response, and the whistling and hissing sounds indicate a compromised boost pressure system. Have you inspected the intercooler or any of the pressure sensor? I would suggest doing that before anything else.

Thanks for the reply. No, I haven't checked those yet. Where exactly are the intercooler and pressure sensor located? And what should I be looking for?

The intercooler on the GLA is typically situated behind the front bumper, its precise location varying depending on the specific configuration of your vehicle. The pressure sensor is generally affixed to the intake manifold or the turbocharger housing. You should examine the intercooler for any physical damage, such as fissures, perforations, or detached hoses. Scrutinize the pressure sensor for any indications of dislodgement, corrosion, or fractured wiring. Given the complexity, I would advocate for a diagnostic evaluation by a certified technician. Based on the symptoms you outlined, in particular the 'turbo lag' and hissing noise, I would not be surprised if the wastegate is indeed the culprit. In my case it was. My final repair bill was roughly 860€.

Thanks a lot, that is very helpful! I'll take a look, but it sounds like it might be beyond my skill level. I'll probably bring it to a workshop. I will mention the wastegate valve and boost pressure when I bring the car in. I appreciate the help!