Blown fuse or fusible link supplying the module's 'C' power circuit.; Corroded, loose, or damaged battery terminal connections or ground straps that affect module power supply.; Open or chafed wire in the harness between the power distribution point and the module connector.; Failed module internal power supply or a faulty internal connection at the module's power input pin.; Water intrusion or corrosion at the module connector causing high resistance or an open circuit.; Aftermarket accessories improperly tapped into the circuit, creating an open or overload.

DTC codes / U30xx · Network wiring and bus faults / U3013

U3013Control Module Input Power C Circuit/Open

Q: What does code U3013 mean?

Control Module Input Power C Circuit/Open. U3013 is a generic network communication code indicating that a control module has detected an open circuit or loss of power on the input power circuit designated as 'C'. The module monitoring this circuit has logged a fault because the expected voltage is missing or out of range, which can prevent that module from operating or communicating on the vehicle network.

U3013 is a generic network communication code indicating that a control module has detected an open circuit or loss of power on the input power circuit designated as 'C'. The module monitoring this circuit has logged a fault because the expected voltage is missing or out of range, which can prevent that module from operating or communicating on the vehicle network.

SystemNetwork

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaNetwork wiring and bus faults

Symptoms you may notice

Illumination of the check engine light or a module-specific warning lamp on the dashboard.
One or more electronic systems (such as stability control, climate control, or lighting) may become inoperative or behave erratically.
The vehicle may fail to start or experience intermittent no-start conditions if the affected module is critical to ignition or fuel delivery.
Communication with a scan tool may be lost for the affected module, preventing diagnostics of other systems.
Often no symptoms besides the warning light, especially if the open circuit is on a non-critical module or a redundant power feed.

Common causes, most likely first

Blown fuse or fusible link supplying the module's 'C' power circuit.
Corroded, loose, or damaged battery terminal connections or ground straps that affect module power supply.
Open or chafed wire in the harness between the power distribution point and the module connector.
Failed module internal power supply or a faulty internal connection at the module's power input pin.
Water intrusion or corrosion at the module connector causing high resistance or an open circuit.
Aftermarket accessories improperly tapped into the circuit, creating an open or overload.

How to diagnose and fix it

Verify battery voltage and condition, then check and replace any blown fuses or fusible links related to the affected module's power circuit.
Inspect the module connector for corrosion, loose pins, or water intrusion, and clean or repair as needed.
Perform a voltage drop test on the power circuit from the battery to the module to locate excessive resistance or an open.
Check the ground circuit for the module, including chassis grounds, for tightness and corrosion.
If the circuit tests good, substitute a known-good module of the same part number to confirm internal failure before replacement.
Repair or replace the faulty section of harness, and clear the code to verify the repair.

Don't overlook the simple power feed

A common oversight is assuming U3013 always means the module itself has failed; in many cases, the fault lies in a corroded fuse box terminal or a chafed wire that only opens under vibration.
The 'C' circuit designation can vary between manufacturers, so always consult the specific vehicle's power distribution diagram to identify which fuse and wire feed the affected module.
Intermittent U3013 codes often set due to a loose battery cable or a failing alternator that causes voltage spikes, so check charging system health before condemning the module.
Some vehicles use a shared power circuit for multiple modules, so a single open can set U3013 alongside other communication codes, misleading you into thinking multiple modules have failed.
Aftermarket alarms or remote starters tapped into the module's power circuit are a frequent cause of open-circuit codes that appear only after the accessory is installed.

Can I keep driving with U3013?

If the vehicle runs and drives normally, you can drive it to a repair shop, but avoid relying on the affected system and do not take long trips until the fault is fixed. If the engine stalls, refuses to start, or multiple warning lights appear, stop driving and have the vehicle towed to prevent safety risks.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.