P0A57: Drive Motor B Current Sensor Circuit Low

P0A57 is set when the signal of the drive motor B current sensor stays below its valid range, usually from a signal line shorted to ground, a missing sensor supply or a failed Hall element. No manufacturer documents P0A57 publicly. A Toyota patent explains the risk of this failure: a sensor held in its ground-short range reports much less current than really flows, the current controller raises its output and can drive the inverter into overcurrent; the system described therefore opens the system relays and warns the driver once the condition repeats. CARB requires out-of-range checks for hybrid input components. P0A58 is the high side, P0A55 the general circuit code, P0A56 plausibility, P0A53 the same check on motor A. Motor B is shut down.

Symptoms

• Hybrid warning and MIL
• Drive motor B or the whole high-voltage system switched off

Most likely causes

• Sensor signal line shorted to ground
• Sensor supply voltage missing
• Hall element of the current sensor failed

What to check, in order

Start with the simplest. You can tick off each step.

1. Read the codes with a hybrid-compatible scanner and write down the freeze frame data
2. With the connector unplugged, check whether the signal wire is making contact with ground.
3. Make sure the battery cooling air intake is clean
4. Check the 12 V auxiliary battery, which can also trigger warnings
5. Leave any high-voltage measurements to a specialized repair shop

Good to know

• It can trigger limp mode.
• It affects emissions.

What each character of P0A57 means

• P: Powertrain: engine and transmission
• 0: Generic code: same on every make
• A: Hybrid or air and fuel
• 57: Specific fault in that system

Frequently asked questions

Can I keep driving with code P0A57?

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 P0A57?

The most common causes are: sensor signal line shorted to ground; sensor supply voltage missing; hall element of the current sensor failed.

Related codes

• P0A58Drive Motor B Current Sensor Circuit High
• P0A55Drive Motor B Current Sensor Circuit
• P0A56Drive Motor B Current Sensor Circuit Range/Performance
• P0A53Drive Motor A Current Sensor Circuit Low
• P0A5BGenerator Current Sensor Circuit Low

Sources

• patents.google.com: en
• law.cornell.edu: 13 CCR 1968.2

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.