NOx Sensor 2871978

BG 201808 (OE 2871978): function on the vehicle

NOx Sensor 2871978 is supplied by BEST GROWTH under part number 201808, cross-referenced to OE 2871978, as a direct-fit aftermarket nox sensors. In service it supplies the emissions-monitoring value the OBD system uses to decide whether the SCR stage is still working within its legal window. A drifting cell triggers inducement long before the catalyst itself is worn out.

BG 201808 is built to the position defined by its OE application on a 12V electrical system on the platform from Cummins. Position, calibration and connector layout are part of the specification, so a part that physically fits is not automatically the correct part.

Because the sensor carries its own control module, most "sensor" faults are really bus, supply or ground faults at the connector — the electrical side is worth ten minutes before the part is ordered.

Fitment for Cummins and OE cross reference

BG 201808 replaces 2 OE references: 2871978 and 5WK9 6674, covering cross applications. Always confirm the number printed on the removed part, including any supersession issued by the vehicle manufacturer.

Recorded vehicle coverage for 201808 includes Cummins, typically on ISB / ISL / ISM Engines. 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 2871978 and quoting the number on your part lets our technical team confirm the variant before despatch.

Symptoms that lead to replacing 2871978

These complaints bring a vehicle in with the Cummins nox sensors under suspicion. None of them prove BG 201808 has failed on its own, which is why the checks below matter before a replacement is ordered.

• torque derate or speed inducement with a full, in-spec DEF tank
• no communication with the sensor control module after a cold start
• sensor value frozen at a fixed number once the exhaust warms up
• dosing shut-down after a few minutes of steady-state running
• upstream and downstream values reading almost identically under load

Checks before fitting BG 201808

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

• Check for exhaust leaks ahead of the sensor boss; a diluted sample reads low NOx.
• Read the sensor's own dew-point release time — a cell that never heats is a supply or module fault.
• Verify DEF concentration with a refractometer before blaming the measuring cell.
• Check for a pending software or parameter update for the sensor control module on that platform.
• After fitting, run the manufacturer's adaptation or relearn so stored efficiency counters reset.

Quality, packaging and ordering 201808

BG 201808 is manufactured and tested to aftermarket replacement standards, with electrical, leakage and functional testing carried out before packing on the 12V specification. Bulk and retail packaging, private-label cartons and customer-specific labelling are available for distributors and workshop groups.

Send OE 2871978 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 201808 replace OE 2871978?

Yes. BG 201808 is listed against 2871978 and 5WK9 6674. Confirm the number printed on the removed part and any manufacturer supersession before ordering.

Which vehicles does BG 201808 fit?

Recorded coverage includes Cummins. It is supplied as a direct-fit aftermarket nox sensors on 12V systems. Adaptation, reset or relearn procedures required by the vehicle manufacturer still apply after installation.

Does this fault code always mean the nox sensors 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 201808.