U3003 code meaning
Battery Voltage
What U3003 means
U3003 is logged when the supply a module measures at its own pins leaves the band it needs; the byte gives the direction: :16 too low, :17 too high, :1C out of range, :68 a logged event. GM's front camera module sets it below 9.0 V or above 16.0 V after 3 s in Run and then switches off adaptive cruise, without MIL. Mazda's MT-006/18 links U3003:16 in the CX-5 and CX-9 power liftgate module to a flat battery: recharge, reset, done. Volvo's TJ 34142 ties PSCM U30031C at cranking in start/stop cars to a battery support module switch and asks for both batteries above 12.4 V; Ford's SSM 49662 reports U3003:68 in the 2018 F-150 steering module after auto start-stop on a low battery. Each module stores its own entry, so several at once point to the battery or charging.
U3003 at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modeNot expected
- Repair difficultyEasy, DIY possible
- Typical labor0.3 to 1.5 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U3003
- Comfort or assistance function inoperative, e.g. power liftgate or adaptive cruise
- Reduced steering assist message during cranking or after start-stop
- The same code stored in several modules at once
Common causes of U3003
- Most likelyLow state of charge or aged 12 V battery
- PossibleAlternator or DC/DC converter charging too little or too much
- PossibleVoltage dip while cranking or restarting in start/stop mode
- Less likelyCorroded fuse, connector or ground in the feed to that module
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
BatteryAlternatorCharging system
What each part of U3003 means
| U | Network system: communication between the control modules (CAN bus). |
| 3 | Reserved range, usually generic. |
| 03 | The exact fault in that area. |
What to do next
- Note U3003 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about U3003
What does U3003 mean?
U3003 means "Battery Voltage". U3003 is logged when the supply a module measures at its own pins leaves the band it needs; the byte gives the direction: :16 too low, :17 too high, :1C out of range, :68 a logged event. It is a generic code, so it means the same on every make.
Is it safe to drive with U3003?
U3003 does not normally turn on the check engine light by itself. Watch for the symptoms above and have it checked soon.
Will U3003 fail an emissions test?
U3003 is not an emissions code, so on its own it usually does not fail an emissions test. Other stored codes or a lit check engine light still can.
How hard is U3003 to fix?
Difficulty: easy. A typical repair takes 0.3 to 1.5 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will U3003 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.