Mercedes-Benz W210 CDI intake manifold flaps: symptoms and troubleshooting
W210 CDI: what symptoms does an intake manifold flap fault cause?
Flaps sticking or the adjusting lever coming off can cause lack of power, revs not rising, smoke and limp mode. The engine management then stores a fault code, so read the fault memory first.
What is checked when a W210 CDI goes into limp mode because of the intake manifold flaps?
Check that the flap actuator motor is electrically intact and moves freely. The motor's cover is glued on and is not available separately, so a faulty motor is replaced as a whole. The flaps can also come off and block the intake passage; the repair belongs to a workshop.
What else can cause the same symptoms as stuck flaps?
Common causes are a detached or cracked vacuum hose, a loose vacuum converter, an intake hose of the EGR valve left open, and a clogged air filter. After flap and intake manifold work, check all the hoses first. The fault can also be in the vacuum part of the turbo or a clogged catalytic converter, so narrow it down by measuring the air volume and boost pressure.