Adblue Circuit - Bosch Denoxtronic-Set 2 Handbuch

1.5.1 AdBlue hydraulic circuit
The central component of the Denoxtronic 2.1 is the delivery module with integrated control unit.
AdBlue is conveyed by the delivery module from the tank to the electrically actuated metering
module at the exhaust system. The required quantity is added at the metering module by way of
an injection valve. The total quantity is considerably higher than what is needed for the
metering. The delivery surplus is used for cooling the metering module (cooling circuit) and
flows back into the tank through a return pipe.
Cooling circuit control valve/fixed restrictor in return pipe
The cooling/return quantity in the AdBlue circuit is influenced by a control valve/restrictor
located in the AdBlue return. One of the three following versions may be fitted depending on
the series status and vehicle manufacturer:
1. In the first years of production, the delivery module was always fitted with an electrically
actuated cooling circuit control valve (CCV, Cooling Control Valve).
2. In a later version, the cooling circuit control valve was replaced by a fixed restrictor in the
metering module. The return pipe is still looped through the delivery module (CCA, Cooling
Circuit Adapter).
3. In a further version the return is routed directly to the tank from the metering module with a
fixed restrictor.
Note: The versions with CCV or CCA can still be built into new vehicles. The version fitted in
the vehicle concerned is shown by the Identification in the diagnostic tester (Section 1.5.2).
It should be noted that the test metering module used is equipped with a fixed restrictor. As a
result, the test procedures vary depending on the system.
AdBlue circuit with cooling circuit control valve (CCV)
1 - AdBlue tank
2 - Delivery module with control unit
3 - Metering module without fixed restrictor
4 - Cooling circuit control valve
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