Code Definition

P0A73 (330) — Generator A phase V current main sensor signal open

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

About P0A73

P0A73 is a generic (obd-ii standard) powertrain diagnostic trouble code recorded for Toyota vehicles. It belongs to the P-prefix family of codes, which covers engine, transmission, emissions, or fuel-system faults.

When P0A73 is stored, the module has detected an open (broken or disconnected) electrical path in the monitored circuit; and 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 P0A73 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

On this Toyota hybrid the Phase V main current sensor for Generator A is integrated into the inverter assembly and gives the MG ECU its primary current feedback for that phase, backed up by a redundant sub sensor. DTC P0A73 with this sub code sets when the MG ECU detects an open circuit in the Phase V main sensor signal line, meaning no valid current data reaches the ECU. The usual causes are a broken or disconnected signal or ground wire, a failed sensor element, or a corroded or unseated connector. With the main feedback lost the hybrid system may reduce or inhibit operation and set warning ...

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