Engine Control Unit issue for 2011 Avensis 2.0 diesel.

[And3Phil]

I wonder if anyone can help. The engine temperature of my 2011 Avensis 2.0 Diesel rises more than it should and the warning light starts blinking ONLY when I drive uphill on the mountains. When I drive downhill or on the highway the engine temperature is fine. I took it to a local garage here in Greece where I came for the holidays and the guy who checked it out said that there is nothing mechanically wrong as everything is working as it should. He told me that the problem lies with the Engine Control Unit which for some reason only recognises that the engine temperature is 70 degrees Celsius all the time. He doesn't know how to rectify the problem but suggests two solutions. Either I always turn on the air condition when driving uphill because the fan works anyway to cool the engine. Or he said that he can find another used  Avensis ECU and install it in my car to solve the issue but that will be more expensive. 

Has anyone experienced anything similar?

Any suggestions on what I should do because I don't know what to do and I have a long drive back to the UK in August.

 

[avetoy]

I wonder if that mechanic has tested the engine temperature sensor?

Changing the ECU sounds like a pretty extreme solution.

[And3Phil]

I will ask him if he has tested it. Changing the ECU does sound extreme. Thanks