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U121A00 — Ionizor, behind frt. pass. side, implausible message

Ionizor, behind frt. pass. side, implausible message. 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 U121A00

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 U121A00

  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 U121A00 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

U120C00Sensor for air quality in the interior, implausible message
U121500Ionizer, driver side, No communication
U121600Ionizer, driver side, implausible message
U121700Ionizor, frt. pass. side, No communication
U121800Ionizor, frt. pass. side, implausible message
U121900Ionizor, behind frt. pass. side, No communication
U123800Heating element 1 control module, No communication
U123900Heating element 1 control module, implausible message
U123A00Heating element 2 control module, No communication
U123B00Heating element 2 control module, implausible message
U123C00Heating element 3 control module, No communication
U123D00Heating element 3 control module, implausible message

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.