OBD-II code · Network (extended)
U300E Ignition Input On
Fault on the ignition ON input — module does not see ON state when other inputs say ON, or vice versa.
Is it safe to drive with U300E?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyIgnition switch contacts worn
- Less likelyGateway module routing CAN messages incorrectly
- Less likelyCAN terminating resistor (120 Ω) drifted out of spec
Symptoms
- Multiple warning lights may illuminate
- Affected modules may go into limp mode or shut down
- Specific functions inoperative depending on module
- Diagnostic tools may show communication faults
Repair at a glance
- Difficulty
- Medium
- DIY friendly
- Often, with basic tools
- Typical labour
- 0.5–2 h
- Emissions test
- Usually unaffected
- Parts involved
- Ignition Input, Wiring
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.