P0AD3: Hybrid/EV Battery Pack Cooling Fan 3 Control Circuit High

With P0AD3 the battery controller finds the control line of cooling fan 3 at a voltage that is too high for the commanded state, pointing to a short to a supply voltage or a fan input that no longer pulls the line down. No manufacturer publicly documents this code; GM's analogous fan 1 code P0A85 trips when the control voltage exceeds 9 V while the fan is driven, Type B. Siblings: P0AD2 for the low side, P0ACF for an open line, P0AD1 if the fan keeps running. CARB 1968.2 calls for this circuit monitoring on battery thermal management parts. Depending on the fault the fan runs permanently or not at all, and the pack may be derated.

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

Hybrid or EV system warning light
Fan 3 runs constantly or not at all
Reduced electric power when the battery is warm

Most likely causes

Control wire shorted to 12 V or another supply
Fan electronics no longer loading the control line
Bent or bridged pins in the fan connector
Battery controller output stage defective

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

Repair difficulty: medium
It can trigger limp mode.
It affects emissions.

What each character of P0AD3 means

P: Powertrain: engine and transmission
0: Generic code: same on every make
A: Hybrid or air and fuel
D3: Specific fault in that system

Frequently asked questions

Can I keep driving with code P0AD3?

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 P0AD3?

The most common causes are: control wire shorted to 12 V or another supply; fan electronics no longer loading the control line; bent or bridged pins in the fan connector.

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.