The automobile dictionary meaning of the U0181 Code is available online but that is not suit well for any brands of car. You should not use this meaning for solving the car engine. Without using proper meaning of the code, it is not possible to solve the car engine. You will get general meaning of the code as general information what has not very informative. For solving the car engine, rely of the actual meaning of the code and you will find that meaning in manufacturer’s provided manual about the code. Read the manual and you will be happy for solving the car engine problem.