Mercedes GLS Hybrid Engine Problems

I had a similar issue with my Mercedes GLS, though not the hybrid Rough idle, check engine light, and reduced power The EGR valve can indeed cause those symptoms A defective EGR valve can affect vehicle emissions and cause the engine to run poorly Have you noticed any difference in the engine sound Does it sound like a vacuum leak

Thanks for the quick reply Yes, sometimes it does sound like a vacuum leak, a kind of hissing noise, especially when accelerating Could that really be connected to the EGR valve I'm trying to figure out if it's something I can tackle myself, or if it's definitely a workshop job Is there any way to confirm it's the EGR valve before I spend a fortune on automotive repair

The hissing noise further suggests an EGR valve issue While some people might attempt a DIY fix, given the hybrid engine and the potential impact on vehicle emissions and the catalytic converter, I would strongly recommend taking it to a reputable workshop They can properly diagnose the issue and replace the EGR valve if needed Trying to fix it yourself might lead to further complications and higher repair costs in the long run

Thanks a bunch for the advice You've confirmed my suspicions I'll book it in with a trusted mechanic Turns out it was indeed the EGR valve, and the total repair cost was 355€ Hopefully, this sorts out the rough running and the check engine light for good