Hello

Few days ago i installed heater to my 2.0tdi cbbb superb.

It works well and heats well when engine its not running but when engine runs and webasto runs, it wont help car to warm any faster than without it.

Now its been +5-7 celcius and it tooks same 8km to open thermostat (checked on obd) no matter webasto or not.

Water pump is rotating right and i installed heater in water hose which comes to heater core. So water which is coming into the heater core goes thru webasto.

Are you certain that the Webasto heater is permitted to operate while the engine is running?

Yes i installed it myself and it has own module where i can but if on/off or ajust by clock. It has no connection to car modules or blower motor etc.

And it has own temp gauge too. It shows pretty same temps than ecu.

Are you sure you have connected to a permanent 12V supply - rather than one that is only live while ignition is off?

Straight to battery +.

is there something on coolant system that "brakes" coolant flow with aux heater?

Is it possible that the heater aux pump is trying to pump against the normal coolant flow direction?

That was i thinking but its correct. Top heater hose is where i installed heater. Block side is now having webasto water pump what pulls coolant thru heater to heater core.

Hose number 3

(I dont have those auxilary hoses which comes with factory heater)

Edited 29 October, 202529 Oct by Karpov

Seems like my thermostat is bad. Tooks too much to gain 80c to 87c. Behr oe quality and lasted only 15k miles :(