Thread: D4 Coolant Level Sensor

I'll just say the coolant level sensor is the only way you're going to know you've had a catastrophic coolant loss before you toast the motor. As the coolant temp sensor sits in the water, once the water is gone it takes a long time to register the increase. In the mean time bad things happen.

In the D3 we replaced the coolant bottle as a whole unit.

On the D3 , The float gets coolant logged and sinks tripping the warning . Easy to replace the whole bottle , so would assume the D4 suffers the same issue .

roverlord sells a good priced replacement.

Cheers Ean

Originally Posted by Ean Austral

On the D3 , The float gets coolant logged and sinks tripping the warning . Easy to replace the whole bottle , so would assume the D4 suffers the same issue .

roverlord sells a good priced replacement.

Cheers Ean

Interesting, I have seen this reported many times but not had the problem (yet) MY08. Same supplier as the dodgy big end bearings perhaps.

I bought a generic replacement bottle and it came with a faulty sensor of all things. In the end I replaced the new aftermarket sensor with my original one. No issues since. I only replaced the bottle as I was doing a coolant flush

D3 / D4, both can have the same issue.

*The sensor can fail if its newer.
*Older as previously mentioned, the float gets coolant logged and sits on the bottom of the expansion tank.

I recommend getting it replaced, as others have said.

I had a coolant low warning come up whilst driving on the highway. I pulled over very quickly and shut down. When I lifted the bonnet the level was normal, what a relief.
Overflow bottle replaced which also gave me the excuse to clean out the intake manifold and replace the plastic coolant manifold as well.

Thanks to all.. I’ll look to purchase a new coolant bottle

I was getting the low coolant level after changing/flushing my coolant, the messages were every time i drove the car despite the levels being correct.

There is a video (on the net) showing that the float will sink in water or float in coolant, suggesting that the float is in fact a hydrometer as well as a level warning.

Anyhow, when refilling mine after many flush cycles I only put in 5 liters of coolant concentrate then about 3 liters of water, that was it, even after bleeding it was full.

With a system capacity of 11.8 liters I needed 5.9 liters of coolant concentrate to get the correct mixture. By sucking out 1 liter and replacing it with concentrate the low coolant warnings are gone, for last week at least. If you were refilling with premix you would have no hope as the system does not fully drain, at least not when draining as per the workshop manual.