lack of good maintenance.
there are lots of reasons, what exactly do you mean?
The most common cause is the engine overheating.
Your bad muffler might be part of the reason your check engine light comes on. Usually, your bad muffler causes something else to go wrong and that causes your check engine light to come on. Problems cascade.
Bad wire
Bad piston rings. Get new engine.
The engine
Yes! At a certain point it causes faoming and lead to lack of lubrication.
Misfire, bad spark timing, bad engine mountings.
Engine sensors will only "go bad" from environmental effects. Lack of oil causes excessive heat. Heat can cause cam sensor failure
The hub bearing can go bad and create noise.
bad bain bering
one of the causes is bad low quality fuel
Bad spark plug?Bad plug wire?Bad valve?*Bad piston?* Do a compression check to check engine internal condition