P0D31: Drive Motor A Inverter Voltage Sensor A Circuit Intermittent/Erratic
Do not keep driving
The car may refuse to move or may run with reduced power. It is a high-voltage system fault and needs a shop equipped for it. If a warning appears while driving, pull over somewhere safe rather than continuing.
What this code means
The circuit for the drive motor inverter's own voltage sensor is faulty.
The inverter measures the voltage arriving at it, and that is a different measurement from the pack measuring what it is sending. The pack's own sense circuits (P0AFA and the P0B14 family) say what the battery is producing at the battery. This sensor says what actually reached the inverter, at the far end of the cables, through the contactors and the fuse. Two measurements of what sounds like one number, taken in different places.
That is exactly why both exist, and a separate code correlates them. Agreement means the high-voltage path between pack and inverter is sound. Disagreement means it is not — a contactor not fully closed, a loose bus bar, a degraded connection heating under load — and that is a fault neither sensor could have found alone.
Without this measurement the inverter will not run, because it cannot set switching timings without knowing its own supply voltage. So a healthy pack and a healthy motor still produce a car that will not move.
The signal comes and goes, or jumps in a way no real voltage could. Intermittent faults on a car that vibrates and heats are nearly always mechanical — a connector not fully seated, a chafed conductor, a terminal that has lost its spring — and they are found by moving the harness with the reading live rather than by measuring a static resistance.
Likely causes
Start here
- Faulty power inverter · specialist
- Corroded or loose connector · specialist
- Open circuit in sensor wiring · specialist
Less common
- Damaged wiring harness · specialist
- Failed sensor reference voltage supply · specialist
Symptoms
Components involved
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
Be the first to write this up
Nothing posted about this yet. Whatever you found is worth writing down — even a dead end saves someone the same afternoon.
What makes one worth reading:
- The car — make, model, year and engine. The same fault behaves differently on each.
- What you measured, not only what you replaced.
- What actually fixed it — or that nothing did, which is worth knowing too.
Sign in or create an account to add what you found about P0D31.