For the first time in nearly 10 years our Panda 4x4 1.2 would not start from cold this morning. She turned over but wouldn't fire and gave a "coolant too hot" warning. Now we had that warning a few weeks ago on first startup but it always went away immediately and it ran fine and at normal temp when warmed up. We stopped getting the message so we planned to get it checked at the soon due service.
We called out the breakdown cover and I rang garages to see who was still open as they are shutting down by us due to Corona*

One garage suggested that the temperature sensor had failed and the engine then refuses to start to protect itself.
Breakdown arrives and gets it started. Said he suspects it was gunk in the fuel line and suggests using Redex to clear it.

So, which diagnosis is right and is Redex safe to use in the 1.2 4x4?

* The soon due service and MOT is now cancelled as the garage shut due to Corona.

Redex won't do any harm
But this is more likely a dirty plug to sensor, dirty sensor or failing coolant sensor problem.

Sensors are set so that a fault triggers the alarm condition. Your problem is most likely a faulty coolant sensor or wiring connector. But obviously check the coolant level and vent the heater hose for air lock just in case.


Redex is snake oil. Do the sums on how much goes through per power stoke and it's far too diluted to do anything. You are better with Shell Optimax. At least that's proven to clean the fuel system and you get better mpg than vanlilla 95RON.