Xsara Engine Power Loss

I had a similar issue with my Xsara. Reduced power and rough running, plus the check engine light. Have you checked your air filter? A clogged filter can mess with the air-fuel ratio. Also, might be worth getting your oxygen sensor checked. If it's faulty, the car might think it needs more fuel than it actually does, causing the rich running.

Thanks for the quick reply! I haven't checked the air filter yet, will do that tomorrow. But how would I check the oxygen sensor? Is that something I can do myself, or do I need special equipment?

Checking the O2 sensor properly usually needs a diagnostic tool to read its output. Honestly, with those symptoms – especially the jerking – and if cleaning or replacing the air filter doesn't fix it, it's probably best to get it to a workshop. Could be the fuel injectors themselves are defective, and that needs proper testing and replacement.

You were right. I took it to a workshop, and after diagnostics, they confirmed a defective fuel injector. They replaced the injector and did an ECU reset. Total cost was 515€. Runs like new now! Thanks for the advice!