Faulty or worn ignition switch or its connector, giving a poor or wrong accessory signal; Wiring damage, corrosion or loose terminals in the accessory feed circuit; Low battery voltage or poor earth or power connections upsetting the control module; Blown fuse or faulty relay in the accessory output circuit; Internal fault in the control module that drives the accessory output; Outdated module software where the manufacturer has issued a known fix for the model.

U302F

Ignition Output Accessory.

Generic
Network
Generic code
Medium severity

How this code is built

U: SystemNetwork
3: Defined bySAE, the same on every car
0: AreaNetwork area 0
2F: FaultThe specific fault in that area

What it means

U302F is listed generically as 'Ignition Output Accessory'. It points to a fault with the accessory ignition output or signal handled by a control module, such as the body control module or ignition switch interface. The module has seen the accessory feed missing, wrong, or disagreeing with other ignition signals. Which module sets it, and the exact circuit, depends on the vehicle, so check the manufacturer's wiring information.

Symptoms

Accessories such as radio, 12V sockets or windows not working in the accessory ignition position
Intermittent loss of accessory power or accessories staying on or off at the wrong times
Warning lights on the dash or other network fault codes stored at the same time
Car difficult to start or ignition position not recognised
Flat battery after parking if an output is stuck on

Possible causes

Faulty or worn ignition switch or its connector, giving a poor or wrong accessory signallikely
Wiring damage, corrosion or loose terminals in the accessory feed circuitlikely
Low battery voltage or poor earth or power connections upsetting the control modulelikely
Blown fuse or faulty relay in the accessory output circuitpossible
Internal fault in the control module that drives the accessory outputpossible
Outdated module software where the manufacturer has issued a known fix for the modelrare

How to diagnose

Read all stored codes and freeze frame data, noting which modules have stored faults and whether the code is current or history
Check battery condition and charging voltage, as low voltage often causes false module faults
Inspect the relevant fuses and relays for the accessory circuit using the vehicle's wiring information
Visually inspect the ignition switch connector and the module connectors for damage, corrosion, moisture or loose pins
Check the live data for ignition switch position and compare it with the actual key position
Measure voltage and voltage drop on the accessory feed with the key in each position, and check the related earths
Wiggle test the harness and switch while watching live data to find intermittent faults
Check for manufacturer software updates or technical bulletins for the model before condemning a module

How to fix

Repair or replace damaged wiring, terminals or connectors, and clean corroded contacts
Replace a faulty ignition switch
Replace blown fuses or faulty relays once the cause of the failure is found
Charge or replace a weak battery and repair poor power or earth connections
Update the module software where a known fault with the calibration is documented
Replace and programme the control module only after power, earth and wiring faults have been ruled out

Can I keep driving?

Medium severity

The car can usually be driven short-term if it starts and runs normally, but get it checked soon as accessories may fail and the battery may drain. If it stalls, will not start reliably, or other safety systems are affected, stop driving and have it inspected.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.