U302E
Ignition Output On.
- 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
- 2E
- FaultThe specific fault in that area
What it means
U302E is a generic network/control module code with the SAE J2012 title 'Ignition Output On'. It points to a problem with the ignition output state that a control module reports or expects, for example an ignition-on signal that is present when it should not be, or that disagrees with what another module reports. The exact trigger and which module sets it vary by vehicle, so check the manufacturer's data for the model.
Symptoms
- Warning lights on the dashboard, possibly with other modules showing communication or warning messages
- Engine cranks but fails to start, or starts and then stalls
- Intermittent loss of power to accessories or modules
- Battery drains while the car is parked, because the ignition feed stays live
- Several other stored codes at once, often voltage or communication related
Possible causes
- Low battery voltage, poor battery condition or a weak charging system causing modules to misread the ignition signallikely
- Poor connection or corrosion at the battery terminals, earth points or ignition feed connectorslikely
- Worn or faulty ignition switch or start/stop button circuit giving an incorrect ignition-on signalpossible
- Damaged wiring, a chafed loop or water ingress in the ignition feed circuit or its connectorspossible
- Faulty relay or fuse in the ignition supply circuit, such as a sticking contactpossible
- Internal fault in the control module that handles the ignition output, or outdated software where the manufacturer has a known fixrare
How to diagnose
- Read all stored and pending codes from every module and note the freeze frame data, paying attention to any voltage or communication codes alongside U302E.
- Test the battery state of charge and charging system output, and correct any low voltage before going further.
- Inspect battery terminals, main earths and the ignition feed fuses and relays for corrosion, looseness or damage.
- Check the ignition switch or start button circuit and its connector for wear, heat damage or moisture.
- Using the wiring diagram for the model, check the ignition feed circuit for voltage drop, shorts and open circuits with the ignition on and off.
- Wiggle-test the harness and connectors while monitoring live data for the ignition status signal to find intermittent faults.
- Check for manufacturer bulletins and software updates for the affected module, as procedures depend on the model.
- Clear the codes after repair and road test to confirm the fault does not return.
How to fix
- Charge or replace a weak battery and repair any charging system fault.
- Clean and tighten battery terminals and earth connections, replacing any that are corroded or damaged.
- Repair or replace damaged wiring or connectors in the ignition feed circuit.
- Replace a faulty ignition switch, start button or relay in the ignition supply.
- Update the module software where the manufacturer lists an outdated calibration as the cause, or replace a confirmed faulty module and code it to the vehicle.
Can I keep driving?
The car can usually be driven short-term if it starts and runs normally, but get it checked soon because the fault may cause stalling or a no-start. Avoid driving if it stalls, loses power or shows several warning lights.
Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.