Battery pack cold-soaked in freezing weather

A traction battery that has stood long enough in freezing conditions for its whole mass to reach ambient, which changes what it can do rather than damaging it. This is a condition, not a fault, and the codes it produces are the system protecting the pack — reading them as component failures is the mistake this entry exists to prevent.

Cold raises internal resistance, so the pack cannot deliver or accept current at its normal rate. Available power falls, voltage sags further under load than usual, and charging is restricted or refused outright because pushing current into a frozen cell plates lithium onto the anode and does permanent harm. A vehicle that will not fast-charge on a freezing morning is very often working exactly as designed.

Two things distinguish it from a genuinely failing pack, and both are easy to check. It follows the weather and the standing time — it appears after a cold night and eases as the pack self-heats or the conditioning system warms it. And it affects the pack evenly; a single weak cell group shows as one module diverging from the others regardless of temperature. Compare cell group voltages while cold: uniformly low is cold, one outlier is a fault. A pack that never warms up in use, though, argues for the conditioning system — a failed heater or coolant valve leaves it cold-soaked indefinitely, and that is a real fault wearing this condition's clothes.