Auris engine power loss

My 2012 Toyota Auris with a gasoline engine is giving me fits. It's got 91170 km and I'm experiencing a serious lack of engine power. The engine warning light is on, and diagnostics show a defective engine control unit. I've checked fuses, but haven't found anything obvious. Could a faulty main relay really cause the ECU to go haywire?

4 comment(s)

I had a similar issue with my old Opel Astra, although that was a diesel. Reduced power and error codes pointing to the ECU. Have you tried a system reset, or disconnecting the battery for a while? Sometimes that clears things up temporarily. What kind of error codes are you seeing specifically?

I did try disconnecting the battery for about half an hour, but no luck. Still the same reduced power and the error code persists. I can't remember the exact code at the moment, but it definitely pointed towards the ECU being the problem. You mentioned your Astra had a similar issue – did it turn out to be the ECU itself, and what was the fix?

Yes, in the end it was the ECU. Sadly, the temporary reset didn't work for me either. After some troubleshooting with the mechanic, the car went straight to the workshop. I'd suggest you take your Auris to a trusted professional to get it properly diagnosed, as it does indeed seem like a defective ECU.

Thanks for sharing your experience! Turns out you were spot on with the relay suggestion. Took it to my local garage, they confirmed the main relay was defective, causing the ECU issues. Replaced it for 120€ and it's running like new again. I really appreciate the help!

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