i Register
In some senses, faulty is marked as obsolete. Watch for register when choosing this word.
adj
Having or displaying faults; not perfect; not adequate or acceptable.
They replaced the faulty wiring and it has worked fine ever since.
I don't think you can infer that from the premise. It's a faulty argument.
At fault, to blame; guilty.
Her faultie Handmayd, which that bale did breede, / Confest, how Philemon her wrought to chaunge her weede.