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P1B8A00 — Change-over valve for medium-temperature circuit (UVW1) – voltage too high
Change-over valve for medium-temperature circuit (UVW1) – voltage too high. 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 P1B8A00
How to read and clear P1B8A00
- 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 P1B8A00 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 Thermal Management
| P1B8400 | Change-over valve for medium temperature circuit (UVW1) – temperature too high |
| P1B8500 | Change-over valve for medium-temperature circuit (UVW1) – voltage too low |
| P1B8600 | Change-over valve for medium-temperature circuit (UVW1) – signal implausible |
| P1B8700 | Change-over valve for medium-temperature circuit (UVW1) – no communication |
| P1B8800 | Change-over valve for medium-temperature circuit (UVW1) – not taught |
| P1B8900 | Change-over valve for medium-temperature circuit (UVW1) – part number implausible |
| P1B8B00 | Expansion valve for evaporator, low-temperature circuit (EXV2) – not taught |
| P1B8C00 | Change-over valve for medium-temperature circuit (UVW2, MVW4), error |
| P1B8D00 | Change-over valve for medium-temperature circuit (UVW2, MVW4), mechanical error |
| P1B8E00 | Change-over valve for medium temperature circuit (UVW2, MVW4), temperature too high |
| P1B8F00 | Change-over valve for medium-temperature circuit (UVW2, MVW4), voltage too high |
| P1B9000 | Change-over valve for medium-temperature circuit (UVW2, MVW4), voltage too low |
All 636 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.