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P1A3900 — Directional-control valve for high-temperature circuit (MVW1) – signal implausible
Directional-control valve for high-temperature circuit (MVW1) – signal implausible. 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 P1A3900
How to read and clear P1A3900
- 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 P1A3900 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
| P194700 | Left radiator fan (RF3) – temperature too high |
| P19FB00 | Directional-control valve for high-temperature circuit (MVW1) – mechanical fault |
| P19FC00 | Directional-control valve for high-temperature circuit (MVW1) – fault |
| P19FD00 | Directional-control valve for high-temperature circuit (MVW1) – voltage too high |
| P19FE00 | Directional-control valve for high-temperature circuit (MVW1) – voltage too low |
| P19FF00 | Directional-control valve for high-temperature circuit (MVW1) – temperature too high |
| P1A3A00 | Directional-control valve for high-temperature circuit (MVW1) – not taught |
| P1A3B00 | Directional-control valve for high-temperature circuit (MVW1) – no communication |
| P1A3C00 | Directional-control valve for high-temperature circuit (MVW1) – part number implausible |
| P1A3D00 | Directional-control valve for medium-temperature circuit (MVW2) – fault |
| P1A3E00 | Directional-control valve for medium-temperature circuit (MVW2) – mechanical fault |
| P1A3F00 | Directional-control valve for medium-temperature circuit (MVW2) – temperature too high |
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.