I started my 2004 Passat this very cold sub zero AM and the coolant indicator flashed on. Under the hood I noticed that the fluid was down about 1/2 inch and smoke or steam was coming from the passanger side-firewall area of the engine compartment. The smoking starts after about a minute after the engine is started. Passat is Front Wheel Drive 1.8L 4 cyl. Any idea what might be wrong?

Suspect head gasket failure.

Is the noise coming from under the dash or under the hood?

You need to check the fluid level on the Transmission. It has to be stone cold when you start the procedure and it is checked and filled from under the car. It also requires a special tool for adding fluid. they don't make it easy to say the least.

Hi,
Please specify wut kind of puddle it is, either oil or coolant?

thermostat

Sounds like air in cooling system. Coolant comes through to back of glove box area for your heat supply.
Have you noticed less available heat than normal?

Check the coolant level in radiator, not just the top up bottle. DO THIS WHEN ENGINE IS COLD as hot system is under pressure.

Possibility of head gasket leak suppling gases to coolant system. IF so may be producing some persistant heavy white steamy exhaust, though not necessarily.

Topping up coolant will (should) make noise go away at least temporarily. You should look to see if any obvious leaks or wet spots at hose clamps and heater hose connections.

When engine is cold, open Radiator cap, look down (flash light helps?) to see fluid level, should be full to top.
If not, top up with correct coolant mix, leaving cap off, start motor and allow to idle till warm. If level drops top off some more. Watch the fluid as it flows past cap opening. a few bubbles for a few mins may be normal, but continous stream of bubbles indicate head gasket leak. Turn on the heat in car to full, (not the fan, just heat level) gently rev the engine and top up fluid at same time, (2 people) replace cap. Done. If there are no apparent problems.

If noise returns or does not go away, you'll need a professional inspection.

Extreme cold weather is causing coolant to contract and fluid level is reading low level ... After starting with the engine warm the temp light should go off due to expansion of the coolant ... Solution: Add a small amount of coolant to compensate for cold weather contraction. Good luck!

It is hydraulic and uses the brake fluid.Follow the line to the gearbox from brake fluid bottle to just under oil filter and there is a small cylinder that can break its seals and stop the clutch working and its easy to replace

we have 2002 passat tdi auto...the brake light on the dash has started flashing when we put it in park with a kind of clicking noise. any ideas?

A red light indicator may signify a hotter temperature, but may not necessarily indicate an overheating condition. A couple things can lead to this condition - low fluid level (check the fluid resevoir), the wrong coolant being used previously, a weak or failing water pump, a plugged or partially plugged coolant radiator, a bad fan, or a bad thermostat. I'd personally check the coolant first, usually needs to be replaced at about 100,000 miles or so, then check to see if you have any leaks if the fluid level is depressed. Then allow the car to operate from a cold start in the drive while observing the performance under the hood and compare it to the dummy light.

Hope this helps.