Hi!

I've bought an Audi A4 B5. When driving, at a random time, the temperature sensor begins flashing. Sometimes the temperature meter goes to 120 for ~10 seconds, then returns to 60. I've checked everything, the diagnostic tool doesn't show anything. Anyone with same problem/solution?

 

could be a coolant temp sensor malfunction. Are you getting any CEL's? Not to start throwing money at the problem immediately... but it's only a $15 dollar part I think.

 

I agree with that. I've already ordered one.

 

basic info like year of vehicle and engine should be included in every post. the easiest way to do this is make a signature or simply add the car info. please!

 

The year is 2000. I thought it would be obvious that it is in the range of 1995-2001 when I wrote the model B5. Thank you for your help and really correct informations. I'll report the results as soon I receive the order.

 

How would that be obvious to me? That is a seven year spread. And if your are in the US, b5's were not offered until 1996. There are vast differences between the years and engines.

People need to know this information. For instance, try walking to the parts counter and asking for a water pump. They will say what year and engine, and if all you give them is "b5", there are 4 different water pumps you would be walking away with.

 

Changed the coolant temp sensor with a new one, still getting the same error. Made few test drives with VAG-COM turned on. Temperature normal after few minutes of driving while the usual error display temp as 120°C after a minute and started flashing.

 

Can you check if it's actually really hot? Like drive for a few minutes (not long!) then park and carefully grab the hoses to see if both sides are hot. I only ask because my last guess is the thermostat. I was really hoping it was the temp sensor because now I'm out of ideas.

 

I'm assuming you checked the coolant level, and it is near max.
Could possibly be air trapped in the system, try bleeding the system and see if that helps.
You bleed by pulling back the heater hose on the firewall partway, which will reveal a hole that will let you bleed air out. Not sure of the exact proper procedure but if you search the forum for "bleed coolant system" you should find it easily. Good luck!