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P0AA400 — Hybrid/EV Battery Negative Contactor Circuit Stuck Closed
Hybrid/EV Battery Negative Contactor Circuit Stuck Closed. 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 P0AA400
How to read and clear P0AA400
- 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 P0AA400 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 Battery Energy Control Module
| P0A9500 | High Voltage Fuse |
| P0A9C00 | Hybrid Battery Temperature Sensor "A" Circuit Range/Performance |
| P0A9D00 | Temperature sensor 1 for hybrid/high-voltage battery - short circuit to ground |
| P0A9E00 | Temperature sensor 1 for hybrid/high-voltage battery - short circuit to B+ |
| P0AA100 | Hybrid/EV Battery Positive Contactor Circuit, Stuck Closed |
| P0AA200 | Hybrid/EV Battery Positive Contactor Circuit, Stuck Open |
| P0AA500 | Hybrid/EV Battery Negative Contactor Circuit Stuck Open |
| P0AA600 | Hybrid/EV Battery Voltage System Isolation Fault |
| P0ABA00 | Hybrid/high-voltage battery total voltage 1 – limit value violated |
| P0ABB00 | Hybrid/EV Battery Pack Voltage Sense "A" Circuit, Range/Performance |
| P0AC000 | Hybrid/EV Battery Pack Current Sensor "A" Circuit, Range/Performance |
| P0AC100 | Hybrid/EV Battery Pack Current Sensor "A", Circuit Low |
All 198 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.