Urea Pump Assembly 4388105

BG 203017 (OE 4388105): function on the vehicle

Urea Pump Assembly 4388105 is supplied by BEST GROWTH under part number 203017, cross-referenced to OE 4388105, as a direct-fit aftermarket def pumps. In service it is the pressure source of the whole DEF circuit, combining pump, filter, pressure sensor and reverting valve in one serviceable assembly.

BG 203017 is built to the position defined by its OE application in truck and industrial engine service on platforms from Scania and Cummins. 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 Scania and Cummins and OE cross reference

BG 203017 replaces 2 OE references: 4388105 and A052Y605. Always confirm the number printed on the removed part, including any supersession issued by the vehicle manufacturer.

Recorded vehicle coverage for 203017 includes Scania and Cummins, typically on SCANIA CUMMINS. 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 4388105 and quoting the number on your part lets our technical team confirm the variant before despatch.

Symptoms that lead to replacing 4388105

These complaints bring a vehicle in with the Scania and Cummins def pumps under suspicion. None of them prove BG 203017 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 203017

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 203017

BG 203017 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 4388105 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 203017 replace OE 4388105?

Yes. BG 203017 is listed against 4388105 and A052Y605. Confirm the number printed on the removed part and any manufacturer supersession before ordering.

Which vehicles does BG 203017 fit?

Recorded coverage includes Scania and Cummins. 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 203017.