U350A

What it means

U350A is a generic network/module code meaning a control module has seen the voltage on one of its power input circuits (labelled 'C') above the expected range. Which module reports it, and which supply pin 'Circuit C' refers to, depends on the vehicle and must be checked in the manufacturer's wiring information. The fault is often linked to charging system overvoltage, but can also be a wiring or module fault.

Symptoms

• Warning lights on the dashboard, such as battery, charging or a system-specific light
• Other modules setting communication or low/high voltage codes at the same time
• Intermittent or erratic operation of the system controlled by the reporting module
• Flickering or unusually bright lights, or odd gauge behaviour
• Reduced function or a system going into a limited mode
• Possible starting problems if the battery or charging system is at fault

Possible causes

• Charging system overvoltage from a faulty alternator or regulatorlikely
• Faulty or incorrectly specified battery, or a battery that has failed internallypossible
• Poor earth or damaged power feed wiring causing wrong voltage at the modulepossible
• Short to a higher voltage supply in the module's power input wiring or connectorpossible
• Incorrect jump start, external charger or aftermarket electrical equipment raising system voltagepossible
• Fault in the vehicle's charge control or energy management system (model dependent)rare
• Internal fault in the reporting control modulerare

How to diagnose

1. Read all stored codes from every module and note freeze frame data, including which module set U350A and the voltage at the time
2. Ask about recent jump starts, charger use, battery replacement or electrical accessories fitted
3. Visually inspect the battery terminals, earth straps, fuses and the connector and wiring at the reporting module for damage, corrosion or heat marks
4. Measure battery voltage at rest, then with the engine running at idle and under load, and compare with the manufacturer's specification
5. Test the battery condition and check that the battery type and rating match the vehicle's requirements
6. Check the alternator output and its control signal or regulator operation using the manufacturer's procedure, as this varies by model
7. Using the wiring diagram, measure the supply and earth at the module's Circuit C pin for the correct voltage and for shorts to other feeds
8. Clear the code and road test, rechecking for return and monitoring live voltage data

How to fix

• Repair or replace the alternator or regulator if charging voltage is above specification
• Replace a faulty battery with the correct specification one, and register it if the vehicle requires this
• Repair or clean damaged wiring, connectors, fuses and earth connections found in the circuit
• Rectify any short to a higher voltage supply in the module's power input wiring
• Remove or correct faulty aftermarket electrical equipment or incorrect charging practices
• Replace or reprogram the control module only after the supply, earths and wiring are proven good and the manufacturer's procedure calls for it

Can I keep driving?

Nearby codes

• U3509GenericControl Module Input Power C Circuit Low
• U350BGenericControl Module Input Power C Circuit Intermittent/Erratic