Home › Fault codes › B156D21
B156D21 — Rear right air distribution servomotor, Lower limit not reached
Rear right air distribution servomotor, Lower limit not reached. The Taycan, 911 (992), Panamera (971), Panamera (972) and Cayenne report this code; below is which control unit sets it on each model and how to read and clear it.
Which models and control units set B156D21
How to read and clear B156D21
- Plug a standard ENET (Ethernet-to-OBD) cable into your Porsche's OBD port and your Mac or Windows PC.
- Open STEUER14, pick your car and run a fault scan: every control unit is read, and B156D21 shows with its status, its full description and the freeze frame when the unit stores one.
- Fix the cause first, then clear the fault memory and scan again to check it stays away. Reading and clearing fault codes is free on every control unit.
More about fault memory in the manual →
Download STEUER14 — free fault readingOther codes of the Central Electrics
| B156C21 | Rear left air distribution servomotor, Lower limit not reached |
| B156C22 | Rear left air distribution servomotor, Upper limit exceeded |
| B156C4B | Rear left air distribution servomotor, Excess temp. |
| B156D04 | Rear right air distribution servomotor, Faulty |
| B156D07 | Rear right air distribution servomotor, mechanical malfunction |
| B156D1C | Rear right air distribution servomotor, Voltage implausible |
| B156D22 | Rear right air distribution servomotor, Upper limit exceeded |
| B156D4B | Rear right air distribution servomotor, Excess temp. |
| B157911 | Refrigerant cut-off valve 1, Short circuit to ground |
| B157915 | Refrigerant cut-off valve 1, Open circuit/short circuit to B+ |
| B158011 | Refrigerant cut-off valve 2, Short circuit to ground |
| B158015 | Refrigerant cut-off valve 2, Open circuit/short circuit to B+ |
All 1472 codes of this control unit →
Fault names come from the manufacturer's diagnostic data. STEUER14 is independent and not affiliated with Porsche AG. A code tells you what a control unit detected, not always which part failed — check wiring, supply voltage and related codes before replacing parts. STEUER14 shows each fault's full description, status and freeze frame on the car.