If a battery pack replacement is quoted off the back of this code, stop and ask how the sense wiring was eliminated. A faulty measuring wire and a failing battery section look identical to the car, and only one of them is a pack. The distinguishing evidence exists — whether the reading moves the way a battery can move — so ask for it by name. Nothing inside a traction pack is a home job.
One of the pack's voltage sense circuits is faulty. Sense A is at P0ABA; B, C and D follow here, and the reason there are several is the point of the page.
A battery pack is a long series string, and its total voltage says almost nothing about its health. Two hundred cells in series produce roughly the same total whether they are all equal or one section is failing while the others compensate. So the pack is tapped at intervals, and the module reads the voltage of each section separately. Several sense lines is how a pack sees where the voltage is, not just how much of it there is.
Which sets up the most expensive misdiagnosis on an electric car. A sense circuit fault and a genuinely weak section produce the same symptom: a section reading low. The module cannot tell them apart, because it only has the wire's word for it — and a wire that has gone high-resistance drops voltage exactly as a tired cell group does.
The discriminator is whether the reading behaves like chemistry. A battery section changes slowly, moves with load and temperature, and stays inside the range its chemistry allows. A faulty sense line does none of that — it steps instantly, moves when the car goes over a bump, or reports a value no lithium cell could hold. Establishing which of those is happening costs a diagnostic session; getting it wrong costs a battery pack.
One physical note that explains why these fail at all: the sense lines are the only thin wires in the high-voltage system. Everything else is heavy cable with substantial terminals; these are signal wires on small connectors, inside the pack, exposed to vibration and to whatever moisture finds its way in. They corrode and fret where the heavy hardware never does.
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.
This is the most expensive misdiagnosis in electric vehicles, and it turns on a distinction the car itself cannot make. Safety first, and not as a formality. Everything below is sc...
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