Code Definition

P0A59 — Alternator current sensor signal error

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

About P0A59

P0A59 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 P0A59 is stored, the module has detected a sensor-related fault — the reported value from the named sensor is out of spec.

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 P0A59 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 current sensor measures the output current of the alternator so the powertrain control module can manage charging voltage and electrical load distribution, often as part of a smart or regulated charging strategy. DTC P0A59 sets when the module detects an invalid, erratic, or implausible signal from this sensor, meaning the reported current does not agree with the expected pattern for the current operating conditions. This usually results from a wiring or connector fault, a reference or ground problem, or a failed sensor. When the code is set the charging system may default to a ...

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