Heating, tank unit (urea injection)

The tank unit heating system, also known as the AdBlue tank heater or heating element of the delivery unit, is an essential component of the SCR exhaust gas system in modern diesel vehicles. Since AdBlue freezes at approximately −11 °C, the heating system ensures that the urea solution in the tank and in the lines leading to the delivery unit is reliably thawed and remains pumpable even under winter conditions. This enables continuous NOx reduction regardless of the outside temperature.

Typical causes of failure include a defective heating element, broken wiring or corrosion at the electrical contacts, a faulty thermostat or temperature sensor, as well as deposits and crystallisation that impair heat transfer. A short circuit in the tank heating control unit can also cause failure. Possible consequences range from delayed system readiness after a cold start and fault codes in the engine control unit to noticeable power reduction or driving restrictions during prolonged frost.