Mercedes Viano starting problems

That sounds frustrating Intermittent issues are the worst Since you've checked the fuses, consider the ignition switch Do you hear the fuel pump prime when you turn the key Does the starter motor engage and crank the engine Or does it do nothing Does temperature matter An ignition coil issue could also mimic those symptoms

Thanks When I turn the key, sometimes I hear the fuel pump, sometimes not The starter motor usually engages and cranks the engine, but not always It doesn't seem related to engine temperature How would I check the ignition coil Can I do that myself with basic tools

The randomness is key Intermittent fuel pump and starter engagement, along with the rough running, points more towards a faulty ignition switch than a simple coil issue Testing the ignition coil properly requires specialized equipment Given what you've described, and the replaced fuse, I'd recommend getting it checked at a workshop Save yourself the headache of chasing potentially unrelated issues

Thanks, I appreciate the advice It turns out it was the ignition switch The workshop confirmed, replaced the faulty part for 52€ and now it runs perfectly Thanks again for your help