Hi everyone,

I have a Superb 2.0tdi 4x4 2013 - The cooling fan kicks in and drops out every few seconds from as soon as I start the engine (cold) until I turn the ignition off, at which point the fan cuts out. I have plugged in a diagnostic device thru the OBD port and no faults are registered. I have switched off the air con and the fan still cuts in and out. I assume it is a sensor that is at fault but I don't know where it might be. Can anyone give some advice please?

Look at the measured values for the coolant temperature in the dash (word 17) and the engine ecu (word 01) to see if they match and are plausible. Also look at radiator outlet temperature.

Then if they are OK, I would check the R134a fill level in the system. Low gas pressure can cause that too. You may be able to see the pressure in the A/C MVBs if it is late enough. I have a charging machine at home so I would pull out the gas and measure what came out. Think it should be 550g if my memory serves. Obviously that is the only way to know if it still has a full charge. If it is low, it then needs a Nitrogen leak test. Don't just fill it with a Halfords special.

G62 is usually down the side of the head near the battery but ages since Ive done one. More likely to be chafed wire or green crusties causing the problem. look for the pastic water pipes with a grey bodied sensor. Change the O ring and clip to avoid disappointment later on ;-)