P0A55 is the general circuit fault of the current sensor that measures the current of drive motor B, typically the second traction motor, for example on a rear axle. The inverter needs this signal for torque control and to protect its power switches. No manufacturer documents P0A55 publicly. A Toyota patent shows the principle behind such checks: a control sensor and a monitoring sensor watch the same motor current, and a sensor stuck in its ground-short range or a lasting gap between the two leads to the relays opening. CARB requires circuit checks of hybrid input components. P0A56 is plausibility, P0A57/P0A58 low and high; P0A51 is the same fault on motor A. Usually drive motor B is switched off and the car drives on reduced power.
High severity. Can I keep driving?If the car still runs, drive as little as possible and go to a specialized repair shop. Do not touch the orange cables: they carry high voltage.
Symptoms
- Hybrid or electric drive warning with MIL
- Drive motor B disabled, loss of electric all-wheel drive or reduced power
Most likely causes
- Current sensor of drive motor B failed (usually inside the inverter)
- Sensor supply or signal line interrupted or shorted
- Evaluation circuit on the motor B control board faulty
What to check, in order
Start with the simplest. You can tick off each step.
Good to know
- It can trigger limp mode.
- It affects emissions.
What each character of P0A55 means
- P: Powertrain: engine and transmission
- 0: Generic code: same on every make
- A: Hybrid or air and fuel
- 55: Specific fault in that system
Frequently asked questions
Can I keep driving with code P0A55?
If the car still runs, drive as little as possible and go to a specialized repair shop. Do not touch the orange cables: they carry high voltage.
What causes code P0A55?
The most common causes are: current sensor of drive motor B failed (usually inside the inverter); sensor supply or signal line interrupted or shorted; evaluation circuit on the motor B control board faulty.
Related codes
- P0A56Drive Motor B Current Sensor Circuit Range/Performance
- P0A57Drive Motor B Current Sensor Circuit Low
- P0A58Drive Motor B Current Sensor Circuit High
- P0A51Drive Motor A Current Sensor Circuit
- P0A79Drive Motor B Inverter Performance
Sources
Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.