AU Low Coolant Light - Not Sensor Problem

[Sfds]

Hi. I’ve checked past threads and I can’t seem to find this exact question having been asked. Apologies if it doesn’t warrant a new thread. I’ve an AU3 XR8 ute and the low coolant light is constantly on. Solid red light comes on about 10 seconds after starting. I’ve bought 3 sensors and checked each before fitting. All are OK, but the light still triggers. All 3 can’t be bad - especially as I “pre-checked” them. When I connect the sensor, but don’t have it installed in the tank, I can open and close the float with my hand and the light will correspondingly come on and go off, as expected. This tells me when I fit the sensor in the tank full of coolant, the light should not show. It might take a few seconds longer, but the light still comes on! Why does the light go on when I’ve checked that the sensor, float and wiring work as they should? I was wondering if I have a slightly warped tank as the sensors look to always sit as a very slight angle. (To me the slight angle seems far too small to make any difference.) I’m wondering if this causes some interference for the float against some internal plastic. Would anyone have an idea. I know I can zip tie the float to the sensor to make it work, but this defeats the purpose. I’m about to buy another Dayco header tank (same part as currently installed DET0002), but in case it’s obvious to someone that it’s something else, I thought I’d try here. Thanks for your suggestions. Cheers