NOx Sensor 55500321

BG 201679 (OE 55500321): function on the vehicle

NOx Sensor 55500321 is supplied by BEST GROWTH under part number 201679, cross-referenced to OE 55500321, 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 201679 is built to the position defined by its OE application on a 12V electrical system in passenger car service on the platform from GM. 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 GM and OE cross reference

BG 201679 replaces 2 OE references: 55500321 and SNS384B, covering cross applications. Always confirm the number printed on the removed part, including any supersession issued by the vehicle manufacturer.

Recorded vehicle coverage for 201679 includes GM, typically on Grandland X 1.5 CDTi 2019-. 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 55500321 and quoting the number on your part lets our technical team confirm the variant before despatch.

Symptoms that lead to replacing 55500321

These complaints bring a vehicle in with the GM nox sensors under suspicion. None of them prove BG 201679 has failed on its own, which is why the checks below matter before a replacement is ordered.

• upstream and downstream values reading almost identically under load
• 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

Checks before fitting BG 201679

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

• 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.
• Check for exhaust leaks ahead of the sensor boss; a diluted sample reads low NOx.

Quality, packaging and ordering 201679

BG 201679 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 55500321 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 201679 replace OE 55500321?

Yes. BG 201679 is listed against 55500321 and SNS384B. Confirm the number printed on the removed part and any manufacturer supersession before ordering.

Which vehicles does BG 201679 fit?

Recorded coverage includes GM. 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 201679.