NOx Sensor RE553440

BG 201252 (OE RE553440): function on the vehicle

NOx Sensor RE553440 is supplied by BEST GROWTH under part number 201252, cross-referenced to OE RE553440, as a direct-fit aftermarket nox sensors. In service it acts as the closed-loop feedback element of the SCR circuit: it tells the controller how much NOx is still leaving the catalyst, so dosing is trimmed up or down instead of running to a fixed map.

BG 201252 is built to the position defined by its OE application on a 24V electrical system in agricultural machinery service on the platform from John Deere. Position, calibration and connector layout are part of the specification, so a part that physically fits is not automatically the correct part.

Cable length and connector keying are part of the specification. A cell with correct electrical output but the wrong lead length will not route to the OE bracket.

Fitment for John Deere and OE cross reference

BG 201252 replaces 2 OE references: RE553440 and 5WK9 6784, covering cross applications. Always confirm the number printed on the removed part, including any supersession issued by the vehicle manufacturer.

Recorded vehicle coverage for 201252 includes John Deere, typically on Combine S650 / S660 / S670 / S680 / S690 / S770. 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 RE553440 and quoting the number on your part lets our technical team confirm the variant before despatch.

Symptoms that lead to replacing RE553440

These complaints bring a vehicle in with the John Deere nox sensors under suspicion. None of them prove BG 201252 has failed on its own, which is why the checks below matter before a replacement is ordered.

• 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
• intermittent fault that clears after the engine cools and returns when hot

Checks before fitting BG 201252

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

• Inspect the harness for heat damage and the connector for moisture and green corrosion.
• 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.

Quality, packaging and ordering 201252

BG 201252 is manufactured and tested to aftermarket replacement standards, with electrical, leakage and functional testing carried out before packing on the 24V specification. Bulk and retail packaging, private-label cartons and customer-specific labelling are available for distributors and workshop groups.

Send OE RE553440 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 201252 replace OE RE553440?

Yes. BG 201252 is listed against RE553440 and 5WK9 6784. Confirm the number printed on the removed part and any manufacturer supersession before ordering.

Which vehicles does BG 201252 fit?

Recorded coverage includes John Deere. It is supplied as a direct-fit aftermarket nox sensors on 24V 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 201252.