B1014 names R12/20, the left front side airbag ignition squib on Mercedes vehicles, and reports a fault on that circuit. Side airbags on these cars are usually built into the seat back, which shapes where the wiring trouble tends to be.
The left front side airbag protects the driver in a side impact and fires through its own igniter. The restraint control unit measures the resistance across that igniter and expects a value in a narrow band. B1014 is stored when the measurement is outside the band, which the module treats as a squib it cannot rely on.
Because the bag lives in the seat, the circuit has to cross from the floor into a seat that slides and reclines. That means a flexing harness section and at least one connector under the seat. Seat removal for carpet work, trim repair, or upholstery is the most common way this circuit gets disturbed, and the damage often does not show until the seat is moved again.
Circuit is the right family for B1014, because the module is reading resistance in real time. The module checks it on every self test, so the code mirrors the present state of the loop. Stored crash data works on a different principle: written at the instant of deployment, kept permanently, and removed only by a module reset rather than by any repair to the wiring.
Clearing the module does not fix a squib circuit that reads out of range, and B1014 will return on the next check. Repair the harness or replace the airbag first. Our mail in reset belongs at the end of the job and only if the module is also carrying crash data, which is common on a car whose side airbag actually deployed.
The make behind B1014 is Mercedes-Benz, and R12/20 is their designation for the left front side airbag squib. Their component numbering is consistent across their own documentation, so R12/20 will lead you to the same part in the wiring diagrams.
Move the driver seat through its full travel while watching the code, because a flex loop that breaks contact at one end of the track gives itself up in seconds. Then unplug the under seat connector, look for spread or green terminals, and reseat it firmly. Measure the loop at the seat connector to decide whether the fault is in the floor harness or inside the seat. We stock genuine OEM Mercedes side airbags when the bag is the problem. Related codes: B100E, B1018, 92-2X.
Trace the wiring and connectors first. If the module still holds the fault after the repair, mail it to us and we will clear it.
Genuine OEM, tested, and shipped ground from Jacksonville, Arkansas.
Do not see it listed? Request a part or call 501-988-0611.