Urea Pump Assembly A0001409678

BG 2039004 (OE A0001409678): function on the vehicle

Urea Pump Assembly A0001409678 is supplied by BEST GROWTH under part number 2039004, cross-referenced to OE A0001409678, as a direct-fit aftermarket def pumps. In service it draws diesel exhaust fluid from the tank, builds and regulates system pressure, and returns fluid during the purge cycle. Filter condition, pressure stability and heater function drive service life.

BG 2039004 is built to the position defined by its OE application in truck service on the platform from Mercedes-Benz. Position, calibration and connector layout are part of the specification, so a part that physically fits is not automatically the correct part.

DEF quality is the single largest driver of pump life. Fitting a new pump into a contaminated tank simply repeats the failure.

Fitment for Mercedes-Benz and OE cross reference

BG 2039004 replaces 2 OE references: A0001409678 and A066S734. Always confirm the number printed on the removed part, including any supersession issued by the vehicle manufacturer.

Recorded vehicle coverage for 2039004 includes Mercedes-Benz, typically on Mercedes Benz. Coverage lists are a starting point for identification, not a substitute for checking the OE number on the vehicle.

Where several OE numbers appear against one BG reference, they are supersessions or regional variants of the same specification. Ordering by A0001409678 and quoting the number on your part lets our technical team confirm the variant before despatch.

Symptoms that lead to replacing A0001409678

These complaints bring a vehicle in with the Mercedes-Benz def pumps under suspicion. None of them prove BG 2039004 has failed on its own, which is why the checks below matter before a replacement is ordered.

• frozen-line faults in cold-climate operation
• repeated dosing interruptions during a drive cycle
• pressure decay immediately after the pump stops
• pressure too low or unable to build pressure
• long priming time after a tank refill

Checks before fitting BG 2039004

Aftertreatment faults are usually system faults. Working through these checks prevents a repeat failure after the new def pumps is fitted.

• Test pressure build-up time and decay against the manufacturer's limits.
• Inspect the DEF filter and tank strainer for contamination and crystallisation.
• Verify heater circuit and coolant valve operation before winter service.
• Confirm DEF concentration with a refractometer; contaminated fluid destroys the pump.
• Check suction and pressure lines for kinks and crystallised blockage.

Quality, packaging and ordering 2039004

BG 2039004 is manufactured and tested to aftermarket replacement standards, with electrical, leakage and functional testing carried out before packing. Bulk and retail packaging, private-label cartons and customer-specific labelling are available for distributors and workshop groups.

Send OE A0001409678 or the number printed on your part, the engine code and the vehicle identification number with your enquiry, and our technical team will confirm the correct reference, current stock position and lead time before you commit to an order.

Frequently asked questions

Does BG 2039004 replace OE A0001409678?

Yes. BG 2039004 is listed against A0001409678 and A066S734. Confirm the number printed on the removed part and any manufacturer supersession before ordering.

Which vehicles does BG 2039004 fit?

Recorded coverage includes Mercedes-Benz. It is supplied as a direct-fit aftermarket def pumps. Adaptation, reset or relearn procedures required by the vehicle manufacturer still apply after installation.

Does this fault code always mean the def pumps has failed?

No. Exhaust leaks, wiring and connector damage, reductant quality, dosing performance and upstream engine faults can all produce the same codes. Validate those inputs before replacing BG 2039004.