Good day everyone. My car is a 2005 model, a 1.4-liter gasoline and LPG-powered 206 automatic transmission. I've been experiencing a knocking sound during gear changes, a late shift, and occasional flashing of the snow and snow lights, regardless of whether it's hot or cold. Most mechanics tell me this is normal, or they all hear a different noise. It's especially noticeable after a steep incline or after traffic, when the car shifts to 3500 rpm and makes a loud knocking noise. My car is also slow to shift into reverse and occasionally knocks when downshifting. They charge exorbitant prices regardless of the vehicle. I'm a student, and unfortunately, this is beyond my budget. My car has also turned on the malfunction indicator light three times, reporting a catalytic converter efficiency (P0420) and hydraulic oil temperature sensor circuit (P0937) failure. I would be very happy if someone who has experienced the same mistake as me or is knowledgeable could enlighten me because this situation is becoming really unbearable for me because of indifferent masters.