NOx Sensor 04L907807BQ

BG 201823 (OE 04L907807BQ): function on the vehicle

NOx Sensor 04L907807BQ is supplied by BEST GROWTH under part number 201823, cross-referenced to OE 04L907807BQ, 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 201823 is built to the position defined by its OE application on a 12V electrical system in truck and bus service on the platform from Volkswagen. Position, calibration and connector layout are part of the specification, so a part that physically fits is not automatically the correct part.

The measuring cell is consumable. Soot loading, silicone contamination and repeated thermal shock all shorten its life, which is why a sensor can drift for months before it sets a hard code.

Fitment for Volkswagen and OE cross reference

BG 201823 replaces 1 OE reference: 04L907807BQ. Always confirm the number printed on the removed part, including any supersession issued by the vehicle manufacturer.

Recorded vehicle coverage for 201823 includes Volkswagen, typically on Bus / Actros / Axor Truck. Coverage lists are a starting point for identification, not a substitute for checking the OE number on the vehicle.

Quote the number printed on your part with the engine code when you enquire; a single-reference part is the most common source of ordering errors when a platform received a mid-life update.

Symptoms that lead to replacing 04L907807BQ

These complaints bring a vehicle in with the Volkswagen nox sensors under suspicion. None of them prove BG 201823 has failed on its own, which is why the checks below matter before a replacement is ordered.

• intermittent fault that clears after the engine cools and returns when hot
• SCR efficiency below threshold or NOx-signal-implausible fault codes
• DEF over-consumption with no visible leak
• torque derate or speed inducement with a full, in-spec DEF tank
• no communication with the sensor control module after a cold start

Checks before fitting BG 201823

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

• 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.
• Compare upstream and downstream NOx readings warmed and under load — idle values prove nothing.
• Confirm supply voltage, ground quality and bus termination before condemning the sensor module.
• Inspect the harness for heat damage and the connector for moisture and green corrosion.

Quality, packaging and ordering 201823

BG 201823 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 04L907807BQ 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 201823 replace OE 04L907807BQ?

Yes. BG 201823 is listed against 04L907807BQ. Confirm the number printed on the removed part and any manufacturer supersession before ordering.

Which vehicles does BG 201823 fit?

Recorded coverage includes Volkswagen. 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 201823.