Code Definition

P063C — Alternator voltage sensing signal Low

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

About P063C

P063C 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 P063C is stored, the module has detected a signal or supply voltage lower 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 P063C 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 fault code P063C is set when the Engine Control Module (ECM) detects that the alternator voltage sensing signal is lower than the expected threshold. This diagnostic trouble code indicates that the voltage level being reported to the ECM from the alternator is insufficient, signalling potential issues with the alternator's output, wiring, or connections in the voltage sensing circuit, or an anomaly in the ECM's ability to correctly read the voltage.

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