U3003 Battery voltage out of range (module supply)
What U3003 means
U3003 is stored by an individual control module when the supply voltage it receives is too high or too low for it to operate reliably. It is not a fault inside the module itself. The cause is almost always the battery, the charging system or a poor connection in that module's power or ground circuit.
U3003 is a generic SAE J2012 code: it means the same on every make. The exact cause still depends on the car, so read the freeze-frame data before replacing parts.
At a glance
- Severity
- Medium
- Typical repair cost
- 80–600 €
- Workshop time
- 0.3–2 h
- Repair difficulty
- Easy
- DIY possible
- Yes
- Check engine light
- Yes
- Affects emissions test
- No
- Limp mode possible
- No
Parts and labour at an independent workshop in Europe. Main dealers charge more; the cause decides the bill, not the code.
Symptoms
- Several warning lights on, sometimes only briefly
- Electrical functions working intermittently
- Slow cranking or difficult starting
- Communication codes stored in other modules
Common causes
- Weak or failing 12 V battery
- Alternator overcharging or undercharging
- Corroded or loose battery terminals
- Poor ground or high resistance in the module power supply
- Code set during jump-starting or while the battery was disconnected
Can I keep driving with U3003?
You can usually keep driving, but have the battery and charging system tested within one or two weeks. A failing battery can leave you unable to start.
What to check first
- Note which module stored the code and read the freeze-frame voltage
- Test the battery and measure charging voltage with the engine running (typically about 13.8 to 14.8 V)
- Clean and tighten battery terminals and check the main ground straps
- Check the power and ground at the affected module; clear the code and see if it returns
Related codes
- U0433 Invalid data received from front distance range sensor
- U0428 Invalid data received from steering angle sensor module
- U0422 Invalid data received from body control module
- U0415 Invalid data received from ABS control module
- U0412 Invalid data received from battery energy control module A
- U0401 Invalid data received from engine control module (ECM/PCM A)
- U0252 Lost communication with rear lighting control module B
- U0184 Lost communication with radio
Data: TORKO fault-code catalogue, built on OBDex (CC0-1.0) and reviewed against workshop practice. Informational only — it does not replace a diagnosis by a mechanic.
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