U3003

Battery Voltage

Moderate severity

The control module detected battery voltage outside its acceptable operating window. Either too low (drained battery, weak charging) or too high (charging system overvoltage).

Common causes

Battery aged or sulfated
One of the most commonly reported causes for this code — check this first.
high
Typical part cost: $90-660
Alternator regulator fault (over- or undervoltage)
A plausible cause — test and verify before replacing parts.
medium
Typical part cost: $90-660
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First things to check

1Confirm the code with a scan tool and check for additional related codes.
2Inspect the relevant sensors, wiring, and connectors for damage or corrosion.

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Related codes

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Frequently asked questions

What does U3003 mean?

U3003 means "Battery Voltage". It is a generic OBD-II code that points to a fault in the network / communication.

What are the most common causes of U3003?

battery aged or sulfated; alternator regulator fault (over- or undervoltage); gateway module routing can messages incorrectly — these are the most commonly reported causes. Verify with a proper diagnosis before replacing parts, or use the Wrenchify app for a vehicle-specific diagnosis.

Can I keep driving with this code?

The vehicle is usually drivable for short distances, but the problem can worsen or affect emissions. Diagnose and repair as soon as practical. Use the Wrenchify app for a full diagnosis specific to your vehicle.

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