What does code U0099 mean?

Q: What does code U0099 mean?

Vehicle Communication Bus H (-) High. U0099 is a generic network communication code indicating that the vehicle's communication bus, specifically the CAN (Controller Area Network) H (-) line, has been detected as high. The computer monitors the voltage on this bus line and sets the code when it sees the signal stuck above the normal threshold, which can disrupt communication between modules.

DTC codes / U00xx · Network wiring and bus faults / U0099

U0099Vehicle Communication Bus H (-) High

U0099 is a generic network communication code indicating that the vehicle's communication bus, specifically the CAN (Controller Area Network) H (-) line, has been detected as high. The computer monitors the voltage on this bus line and sets the code when it sees the signal stuck above the normal threshold, which can disrupt communication between modules.

SystemNetwork

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyProfessional

AreaNetwork wiring and bus faults

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.