P0C30: Hybrid/EV Battery Pack State of Charge High

P0C30 is the counterpart of P0A7D: the battery controller finds that the state of charge of the high-voltage pack stays above its usable window. CARB requires hybrid OBD to flag a state of charge that can no longer be kept inside the manufacturer's range. GM's 2019 hybrid table 19OBDG01 describes the method: the SOC is checked once per drive cycle, the controller first allows time for the motor to draw the charge back down, then counts the distance driven with excessive SOC; if that share exceeds half of a trip longer than 50 km, at speeds above 15 km/h and pack temperature at least −10 °C, the code is stored as Type B, two trips. No other manufacturer documents it publicly. The car limits regeneration and charging to protect the cells, so braking feel and fuel economy can change.

High severity. Can I keep driving?If the car still runs, drive as little as possible and go to a specialized repair shop. Do not touch the orange cables: they carry high voltage.

Symptoms

MIL after two trips
Reduced or no regenerative braking
Changed brake pedal feel and higher fuel consumption

Most likely causes

Wrong SOC estimate from a drifting pack current or voltage measurement
Battery or hybrid control software not drawing the charge down as intended
Electric assist blocked by another fault, so the pack cannot discharge

What to check, in order

Start with the simplest. You can tick off each step.

Read the codes with a hybrid-compatible scanner and write down the freeze frame data
Check the sensor's ground and make sure the signal wire is not receiving voltage from another circuit.
Make sure the battery cooling air intake is clean
Check the 12 V auxiliary battery, which can also trigger warnings
Leave any high-voltage measurements to a specialized repair shop

Good to know

It can trigger limp mode.
It affects emissions.

What each character of P0C30 means

P: Powertrain: engine and transmission
0: Generic code: same on every make
C: Subsystem depends on the code range
30: Specific fault in that system

Frequently asked questions

Can I keep driving with code P0C30?

If the car still runs, drive as little as possible and go to a specialized repair shop. Do not touch the orange cables: they carry high voltage.

What causes code P0C30?

The most common causes are: wrong SOC estimate from a drifting pack current or voltage measurement; battery or hybrid control software not drawing the charge down as intended; electric assist blocked by another fault, so the pack cannot discharge.

Related codes

Sources

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.