U3003 on Mazda
Battery Voltage
U3003 on Mazda vehicles indicates battery voltage. Au7o has documented this code across 1 Mazda model — most commonly on CX-30. U3003 is a generic code meaning a control module detected that its supply (battery/system) voltage was outside its normal operating range — either too low or too high. Modules need a stable voltage (roughly 12 to 14.5 volts) to work reliably, and out-of-range voltage can cause erratic module behavior and set this code. It is frequently a symptom of a weak battery or charging-system problem rather than a fault in the module itself.
Common Causes of U3003
- •Weak, discharged, or failing battery
- •Faulty alternator / charging system (under- or over-charging)
- •Corroded or loose battery terminals or cables
- •High-resistance ground or power connections
- •Poor module power/ground circuit
- •Excessive parasitic draw
- •Voltage drop from corroded fuse box or connectors
U3003 on Mazda by Model
Mazda CX-30(1 issue)
- Climate Control Unit and Body Control Module Fail to Enter Sleep Mode - Parasitic 12V Battery Drain (SSPC5)2020-2024
Mazda issued Special Service Program SSPC5 for the CX-30 covering multiple control-module reprogramming concerns, the first of which is a battery concern: the climate control unit (CCU) and body control module (BCM) may not transition into sleep mode after the ignition is switched OFF. The modules stay awake and draw current continuously, flattening the 12V battery over a few days of non-use. Owners report the low-battery warning after short parking periods, no-start conditions, and in several documented cases repeated tow-ins with batteries that still pass Mazda's own load specification - the classic signature of a parasitic draw rather than a failed battery. Complaints persist on later model years beyond the original SSPC5 population, and the i-stop system's sensitivity to state of charge makes the symptom show up early as i-stop simply refusing to work. Note this is distinct from recall 25V357, which concerns what the air bag sensor does after a battery is already dead.
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View U3003 across all makes →Frequently Asked Questions
What does U3003 mean on Mazda?▼
U3003 stands for "Battery Voltage." U3003 is a generic code meaning a control module detected that its supply (battery/system) voltage was outside its normal operating range — either too low or too high. Modules need a stable voltage (roughly 12 to 14.5 volts) to work reliably, and out-of-range voltage can cause erratic module behavior and set this code. It is frequently a symptom of a weak battery or charging-system problem rather than a fault in the module itself. On Mazda specifically, this code is documented across 1 model.
What causes U3003 on Mazda vehicles?▼
Common causes on Mazda: Weak, discharged, or failing battery, Faulty alternator / charging system (under- or over-charging), Corroded or loose battery terminals or cables, High-resistance ground or power connections, Poor module power/ground circuit. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix U3003 on a Mazda?▼
Repair costs vary widely depending on the root cause and specific Mazda model.
Which Mazda models have U3003 documented?▼
Au7o has documented U3003 on 1 Mazda model: CX-30.