The brief
The CLA180 had developed an unsettled idle the owner could feel through the steering wheel at red lights, the engine had lost some pull off the line, and a check-engine light was on. He brought it in for a proper diagnosis rather than a guess.
This engine uses CAMTRONIC, Mercedes' variable valve lift system, where small solenoid valves switch the cam profiles to suit load and revs. When one of those solenoids jams, the engine is stuck on the wrong cam setting, so it idles roughly and feels flat when you ask for power, and it logs a fault. The symptoms the owner described are exactly what a jammed CAMTRONIC solenoid feels like.
The diagnosis
The scanner told the story. There were CAMTRONIC solenoid faults on cylinder bank 1, jammed in the on position, and the live data showed the valves not responding cleanly to what the engine controller was asking for. The intake-side solenoid was the live fault, and the scan showed its exhaust-side partner had jammed too.
A bench-test on the solenoids confirmed them. So the fix was to replace the failed CAMTRONIC solenoids, not clean them, and since they're the same part and the same age, both went on the list.
The work
The failed CAMTRONIC solenoids were removed, and new Mercedes-spec replacements went on with fresh seals, the harness reseated.
Then the adaptation routine was run on STAR so the engine controller re-learned the open and closed positions of the new valves, and the stored fault codes were cleared.
A road test confirmed the engine idled steady, pulled cleanly off the line, and the light stayed off through a full drive cycle.
The outcome
The idle is steady again, no shake through the wheel at lights, the throttle response is back, and the check-engine light hasn't returned after a drive cycle.
The CLA180 went home running cleanly through the rev range. A jammed CAMTRONIC solenoid is a small actuator with a big effect on how the engine runs, and replacing the failed pair and letting the controller re-adapt is what gets the variable valve system back to switching the way it's meant to.