GLS Diesel Running Lean Help

I had similar issues with my GLS, though it was a while back. Reduced power and the check engine light were the first signs. Did you notice any changes in fuel consumption or any unusual smells? It could be the injectors, but before you dive into that, have you looked at the fuel filter? A clogged filter can restrict fuel flow and cause a lean condition. Also, consider a smoke test to rule out any vacuum leaks in the intake manifold system. It might save you some money before replacing the injectors. How many kilometers on yours?

Thanks for the reply! Fuel consumption seems a bit higher than usual, but I hadn't really paid close attention to smells. I replaced the fuel filter about 20000 km ago, but it might be worth checking again. What was the eventual fix for your GLS? Did it turn out to be the injectors, or something else?

Yeah, mine turned out to be a faulty injector. The check engine light was driving me crazy! Given your symptoms and the lean code, it's quite possible. I'd suggest getting a proper diagnostic check at a workshop to confirm which injector(s) are the culprit. They can also check the fuel pressure and do a more thorough inspection of the EGR valve and intake system. Better to be sure before throwing parts at it, you know?

Took your advice and brought it to a trusted workshop. Turns out it was indeed a defective injector on cylinder 3. Replaced it, and the car runs like new again. Total cost was around 515€. Thanks for the help!