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B126A04 — Main light switches – defective

Main light switches – defective. 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 B126A04

Porsche Taycan

Central Electrics

Porsche 911 (992)

BCM1 (Body Control Module 1)

Porsche Panamera (971, 2017–2023)

BCM1 (Body Control Module 1)

Porsche Panamera (972, 2024–)

BCM1 (Body Control Module 1)

Porsche Cayenne (9YA)

BCM1 (Body Control Module 1)

How to read and clear B126A04

  1. Plug a standard ENET (Ethernet-to-OBD) cable into your Porsche's OBD port and your Mac or Windows PC.
  2. Open STEUER14, pick your car and run a fault scan: every control unit is read, and B126A04 shows with its status, its full description and the freeze frame when the unit stores one.
  3. 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 reading

Other codes of the Central Electrics

B122015Right fog light bulb, Open circuit/short circuit to B+
B126111Windshield washer pump/rear camera – short circuit to ground
B126211Night vision/ACC washer pump – short circuit to ground
B126215Washer pump for night vision system/ACC – short circuit to B+ or open circuit
B126611Rear window defogger button, Short circuit to ground
B126629Rear window defogger button, Implausible signal
B126A29Main light switches – signal implausible
B126AF0Main light switches – button status implausible
B126AF1Main light switches – button status implausible
B126AF2Main light switches – part number implausible
B128104Weather sensor (rain/light/moisture) – defective
B12A104Left indirect ventilation flap motor, Faulty

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.