Should I worry about the coolant warning light in a Passat?

Hi, I'm currently looking to move to a diesel as my new job has me doing a far longer commute. I've spotted a second hand '03 VW Passat 1.9 TDI that I like the look of. I did a full history check on the vehicle and it seems genuine. Only issue is that the coolant warning light is flashing when the coolant level is fine. A friend suggested it could be the sensor needs to be replaced, but I don't want to buy if it's something more serious. Is this a common problem with VWs?

Thanks. Sean.

Sean McDermott (Cork)

Nov 2010 Filed under: fault

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Expert answer

Hi Sean,

Stephen McDonnell from Volkswagen Ireland contacted us with some really useful information on this. Apparently the sensors themselves are quite robust, but they can be fooled into thinking the level is low by poor quality coolant. So, if there's more water than coolant in the car it may not register properly. Likewise, if there's oil in the water it could throw up a strange reading.

So, the advice is to have a look at the quality of the coolant and ask the buyer when it was last changed.

It could still be the sensor, but it's more likely that the above is the reason for the warning light.

Hope that helps,

Shane O' Donoghue - Complete Car Adviser
@Shane_O_D