Cummins AdBlue pump for Scania, DAF, Mercedes

The 5506956 is the DEF metering pump (AdBlue) used in latest-generation Cummins, Scania, DAF and Mercedes SCR systems. Its task is to draw the fluid from the tank, pressurize it and feed the urea injector with a stable flow rate and pressure, ensuring proper NOx reduction and vehicle operation without derating. It is a compact unit for non-air-assisted systems (“non-air assisted”), designed for medium-heavy on-road applications.

Technical specifications

• Type: DEF metering pump module for closed-circuit SCR systems, without air-assist.
• Power supply: 24 V (heavy vehicle applications).
• Function: generation and regulation of DEF pressure to the injector; management of priming and purge cycles.
• Typical operating pressure range: ~4.5–9 bar (≈65–130 psi) at steady state, depending on the ECU strategy and system layout.
• Connections: quick-connect DEF lines on suction/discharge side; vehicle electrical interface according to engine wiring.

DIPA offers a range of original and equivalent-quality aftermarket spare parts.

Functions

• Priming and pressurization of the urea circuit with closed-loop control.
• Pressure stabilization during dosing phases to maintain NOx conversion efficiency.
• Shut-down purge cycles to limit DEF crystallization in the lines.
• Support for active ECU tests (pump/injector command) for workshop diagnostics.

Model applications

• Cummins ISB/B6.7 engines (EPA17/Euro VI and later evolutions) on medium-duty on-road vehicles, buses and vocational applications.
• DAF
• Mercedes
• Scania

Common faults

• Insufficient pressure due to pump wear, partially blocked filter/lines from crystals, or air ingress into the circuit.
• Unstable/excessive pressure due to control malfunction or faulty pressure sensor.
• DEF crystallization in hot/cold areas with ineffective purge cycles.
• Electrical issues: voltage drops, corroded grounds, damaged connectors/wiring.
• DEF freezing or insufficient circuit heating resulting in reduced flow when cold.
• Partially blocked metering injector → backpressure returns and related fault codes.

Final conclusions

The 5506956 is a key component for SCR reliability: when malfunctions are experienced, workshop practice shows it is advisable to check the fluid condition, line integrity, electrical supply, filter/collector and the injector.

DIPA offers a wide range of spare parts: from originals to selected aftermarket items from the best manufacturers on the market. In addition, it offers remanufactured components with like-new performance, which provide cost savings on replacement and help protect the environment through the circular economy. If the spare part you need is not available, don’t worry: DIPA can remanufacture your unit “on demand”, returning it to full functionality and safety in a short time.