NOx Sensor 4K0907807AK

BG 990782 (OE 4K0907807AK): function on the vehicle

NOx Sensor 4K0907807AK is supplied by BEST GROWTH under part number 990782, cross-referenced to OE 4K0907807AK, as a direct-fit aftermarket nox sensors. In service it runs a heated zirconia measuring cell inside its own sensor control module, converts the raw cell current into a NOx value in ppm, and publishes it on the bus. The engine controller cannot calculate dosing quantity or conversion efficiency without a plausible signal from it.

BG 990782 is built to the position defined by its OE application on a 12V electrical system 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.

Fitting position matters as much as the part number: upstream and downstream references often share a housing but carry different calibration data and cable lengths.

Fitment for Volkswagen and OE cross reference

BG 990782 replaces 2 OE references: 4K0907807AK and SNS0791B, covering cross applications. Always confirm the number printed on the removed part, including any supersession issued by the vehicle manufacturer.

Recorded vehicle coverage for 990782 includes Volkswagen, typically on A7 Sportback 2018-2024. 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 4K0907807AK and quoting the number on your part lets our technical team confirm the variant before despatch.

Symptoms that lead to replacing 4K0907807AK

These complaints bring a vehicle in with the Volkswagen nox sensors under suspicion. None of them prove BG 990782 has failed on its own, which is why the checks below matter before a replacement is ordered.

• 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
• sensor value frozen at a fixed number once the exhaust warms up

Checks before fitting BG 990782

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

• 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.
• 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.

Quality, packaging and ordering 990782

BG 990782 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 4K0907807AK 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 990782 replace OE 4K0907807AK?

Yes. BG 990782 is listed against 4K0907807AK and SNS0791B. Confirm the number printed on the removed part and any manufacturer supersession before ordering.

Which vehicles does BG 990782 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 990782.