Code Definition

P0A71 — Alternator phase U current high

System: Powertrain  |  Type: Generic (OBD-II Standard)  |  Make: Generic

About P0A71

P0A71 is a generic (obd-ii standard) powertrain diagnostic trouble code. It belongs to the P-prefix family of codes, which covers engine, transmission, emissions, or fuel-system faults.

When P0A71 is stored, the module has detected a signal or supply voltage higher than the expected operating range.

Scanning & clearing: A generic OBD-II scan tool will usually read and clear powertrain (P) codes. For live data, freeze-frame capture, and bi-directional tests you may need a more capable scan tool that supports the vehicle's ECM protocol.

Because P0A71 is a generic OBD-II code, its base definition is shared across manufacturers. The specific diagnostic steps, reference values, and repair procedures can vary by vehicle, and the TaT Diagnostic Assistant includes verified procedures submitted by working technicians.

Code Information

The alternator stator generates three phase AC that is rectified to DC for charging, and the charging control module monitors all three phases to keep output balanced and protect the system. DTC P0A71 sets when the current in Phase U exceeds its calibrated upper threshold during operation. An abnormally high reading usually indicates a low resistance path or excessive field, such as a shorted stator winding, a shorted rectifier diode, a short on the phase wiring, an overcharging regulator fault, or a current sensor that over reports. The fault can cause overcharging, thermal stress on the alte...

Join TaT to view the complete code information and diagnostic details.

Quick Facts