Yaris diesel power loss

Reduced power and a stored error code? Sounds like a classic case of something's not right! Have you had any modifications done to the ECU, like chip tuning? Those things can cause more problems than they solve. It's like putting a bigger engine in a toy car; it might go faster for a bit, but eventually, something's gonna break. What diagnostic code did the scan tool give you? That's key to figuring this out.

Thanks for the quick response. I did have some chip tuning done a while back. The diagnostic code is pointing towards some issue with the fuel injection system. Is it possible the chip tuning is causing the error, and do you have any recommendations what to do?

Fuel injection issue after chip tuning? Bingo! It's highly likely that the tuning is the culprit. Think of it like this: the car computer is now trying to run settings that the engine isn't designed for, like trying to force a square peg into a round hole. I'd say it's best to have the chip tuning checked by a specialist, or, even better, reversed. Eventually you would need to visit a workshop.

Thanks for confirming my suspicions and the prompt replies! As you suggested, I reverted the chip tuning to the original settings at a specialist workshop. They confirmed it was causing the error with the fuel injection system. Total repair cost was 180€. The Yaris is running smoothly again!