U302E code meaning
Ignition Output On
What U302E means
U302E applies to an output intended to carry voltage in On alone, which means it has to switch off while the starter turns. The driving module must blank out that intended gap during cranking and judge the output only in steady power modes, otherwise every start would log the code. How such a check can be built is shown in Yazaki's patent CN106797120A: a controller measures the voltage behind a second ignition relay, treats a reading below a threshold set between nominal voltage and 0 V as a relay that failed open, warns the driver on a display and moves the affected loads over to the first ignition feed. Transferred to U302E, a dead output in On points to a relay stuck open, a blown fuse or a broken wire, while voltage in Off points to a welded contact or a driver stuck on. No manufacturer documents U302E publicly.
U302E at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modeNot expected
- Repair difficultyMedium
- Typical labor0.5 to 3 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U302E
- Loads on the run-only feed dead with the engine running
- Power supply warning in the cluster
- Battery discharged when the output stays on after shut-off
Common causes of U302E
- PossibleRun relay not closing, e.g. burnt contacts or open coil
- PossibleBlown fuse or broken wire behind the relay
- PossibleWelded contact or driver stuck on, leaving the output live in Off
- Less likelyModule software judging the intended cut during cranking as a fault
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Ignition outputIgnition relayOutput wiring
What each part of U302E means
| U | Network system: communication between the control modules (CAN bus). |
| 3 | Reserved range, usually generic. |
| 2E | The exact fault in that area. |
What to do next
- Note U302E and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about U302E
What does U302E mean?
U302E means "Ignition Output On". U302E applies to an output intended to carry voltage in On alone, which means it has to switch off while the starter turns. It is a generic code, so it means the same on every make.
Is it safe to drive with U302E?
U302E does not normally turn on the check engine light by itself. Watch for the symptoms above and have it checked soon.
Will U302E fail an emissions test?
U302E is not an emissions code, so on its own it usually does not fail an emissions test. Other stored codes or a lit check engine light still can.
How hard is U302E to fix?
Difficulty: medium. A typical repair takes 0.5 to 3 hours of work. This is a job for a workshop.
Will U302E clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.