Berlingo Overheating Coolant Leak

Overheating and coolant spill suggests more than just a communication error. However, a faulty CAN bus could cause erratic sensor readings that lead to the engine management system misinterpreting temperatures and over-pressurizing the cooling system. Is the temperature gauge reading abnormally high before the coolant spill?

The temperature gauge does climb pretty rapidly before things get messy with the coolant. So, you reckon a dodgy CAN bus could be feeding the ECU false temp data, causing it to overreact? If it's the CAN bus, how would I start tracing the fault? Multimeter and wiring diagrams?

Rapid temperature increase combined with coolant issues does point to a sensor problem being likely. A defective cable or plug connection of a component could lead to the described symptoms. Given the symptoms, pinpointing the exact cause without proper diagnostic tools will be difficult. I'd recommend getting it checked at a workshop. They will have tools to check the error memory, read the sensor data and verify the data via the CAN bus.

I took it to a shop as suggested. Turns out it was a corroded connector on one of the temperature sensors, messing with the CAN bus data. They cleaned it up and replaced a short section of wiring. Cost me 95€ all in. Seems to have sorted the overheating issue and the coolant leak. Cheers!