faultier , faultiest
A faulty piece of equipment has something wrong with it and is not working properly.
The money will be used to repair faulty equipment.
这笔钱将被用来修理出故障的设备。
If you describe someone's argument or reasoning as faulty, you mean that it is wrong or contains mistakes, usually because they have not been thinking in a logical way.
Their interpretation was faulty – they had misinterpreted things.
他们的解释是错误的–他们曲解了事物。