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B166E04 — Windshield heater relay – defective
Windshield heater relay – 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 B166E04
How to read and clear B166E04
- 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 B166E04 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 Comfort System Module
| B158A29 | Central locking button on front left outer door handle – signal implausible |
| B158B29 | Central locking button on front right outer door handle – signal implausible |
| B158C29 | Central locking button on rear left outer door handle – signal implausible |
| B158D29 | Central locking button on rear right outer door handle – signal implausible |
| B15F811 | Antenna for central locking system – short circuit to ground |
| B15F813 | Antenna for central locking system – open circuit |
| B166E16 | Windshield heater relay – voltage too low |
| B166E17 | Windshield heater relay – voltage too high |
| B166E29 | Windshield heating relay – signal implausible |
| B166E31 | Windshield heater relay – no signal |
| B1678F0 | Radio key – not synchronized |
| B169011 | Tailgate proximity sensor control unit, supply voltage – short circuit to ground |
All 616 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.