Generic (OBD-II) interpretation in the TuningBot DTC database.
U · NetworkNetworkOBD2
What U300B means
U300B
Ignition Input Accessory/On/Start
Generic · network
Data confidence78%
The control module detected a fault associated with the Ignition Input Accessory/On/Start circuit or function; the stored code identifies the affected component rather than a single failure mode.
Symptoms
Multiple warning lamps possible
Functions of the affected module unavailable
Possible causes
CAN bus wiring fault (open, short, chafed harness)
Faulty control module loading the bus
Connector or terminal corrosion
Power supply or ground fault of a module
Recommended checks
Perform a full-module scan to map which modules communicate
Check CAN bus resistance and voltages at the diagnostic connector
Inspect wiring and connectors of the affected module
Check module power supply and grounds
Disconnect suspect modules one at a time only with a documented procedure
Generic SAE-standard code: same meaning on every make.
00B
Specific fault index within the subsystem.
Frequently asked questions about U300B
What does U300B mean?
Ignition Input Accessory/On/Start. The control module detected a fault associated with the Ignition Input Accessory/On/Start circuit or function; the stored code identifies the affected component rather than a single failure mode.
Is U300B generic or manufacturer-specific?
U300B is a generic OBD-II code: it has the same meaning on every make and model that follows the SAE standard.
Can TuningBot remove U300B at file level?
Not guaranteed. Powertrain (P) codes can be reliably disabled in the ECU calibration, but body, chassis and network codes depend on the specific control unit and how the fault is implemented - some can be handled, some cannot. Ask for a quote and our engineers will check your file and tell you, free of charge, whether U300B is removable in your case.
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