BodyB121D
CautionSeverity: Caution - get it checked when you can
Rear HVAC Mode Control Input
Key terms: Control module: a small computer that runs one part of the car
1What it means in plain English
A body system has a fault. Depending on the make, this range can include airbags and seat belts, windows, locks and climate control, and also charging, brake, oil or coolant sensors.
2Common causes
- Wiring or connector fault
- Faulty sensor or switch
- Water or corrosion in a connector
- Control module fault
- Low battery voltage
3Can I drive?
Do not assume this code is safe to drive. If it concerns the brakes, brake vacuum, charging/alternator, engine oil or coolant, have it diagnosed before driving. Airbags or seat belts may not work in a crash, and a brake or charging fault can leave the car unsafe or stranded. For convenience systems (windows, locks, climate), have it checked when convenient.
This page gives general information. It is not professional advice. For a definite diagnosis and a repair quote, ask a qualified mechanic to inspect the car.
4Brand data 15
| Brand | Code | Description | System |
|---|---|---|---|
| Mercedes-Benz | B121D | No description available | Body |
| BYD | B121D | IGBT 4 drive function failure Brand | Body |
| Daewoo | B121D | No description available | Body |
| DFFS | B121D | Intelligent control box internal fault related to adaptive cruise control Brand | Body |
| Geely | B121D | Front Row Right Side Side Airbag Igniter Grounding Brand | Body |
| GM | B121D | No description available | Body |
| Holden | B121D | Windshield Wiper Relay Circuit Brand | Body |
| Honda | B121D | No description available | Body |
| Land Rover | B121D | Rear HVAC Mode Control Input Brand | Body |
| Mitsubishi | B121D | No description available | Body |
| Opel | B121D | No description available | Body |
| Peugeot | B121D | No description available | Body |
| Proton | B121D | No description available | Body |
| Saab | B121D | No description available | Body |
| Suzuki | B121D | S/L LOCK PWR SPLY CIRC Brand | Body |
Legend: SAE is the generic J2012 description; Brand is text taken from that manufacturer’s data. Manufacturer rows keep the wording and language of the source data, and non-English text is tagged so screen readers pronounce it correctly.
5Extended variant codes 8
These 7-character codes are manufacturer-specific variants of B121D and may be reported by some scan tools.
| Brand | Code | Description | System |
|---|---|---|---|
| Mahindra | B121D01 | HV Battery Cut Off Pyro Switch - Cross Connect Brand | Body |
| Mahindra | B121D11 | HV Battery Cut Off Pyro Switch - Short To Ground Brand | Body |
| Mahindra | B121D12 | HV Battery Cut Off Switch - Short To Battery Brand | Body |
| Mahindra | B121D13 | HV Battery Cut Off Pyro Switch - Open Circuit Brand | Body |
| Mahindra | B121D1A | HV Battery Cut Off Pyro Switch - Low Resistance Brand | Body |
| Mahindra | B121D1B | HV Battery Cut Off Pyro Switch - High Resistance Brand | Body |
| Mercedes-Benz | B121D64 | Current sensor 1 of the refrigerant compressor has a malfunction. There is an implausible signal. Brand | Body |
| Mahindra | B121D64 | HV Battery Cut Off Pyro Switch - Unexpected Squib Brand | Body |
6Related codes
Browse Bxxx codes or B121xx codes.