Could black smoke from exhaust be caused by clogged air filter?

Restricted air = rich mixture = black smoke. Cheapest fix.

Could black smoke from exhaust be caused by faulty mass airflow sensor?

Bad MAF readings make the engine dump extra fuel.

Could black smoke from exhaust be caused by bad o2 sensor?

Bad readings cause incorrect fuel trim.

Could black smoke from exhaust be caused by failing fuel pressure regulator?

Sends too much fuel to the injectors.

Black Smoke From Exhaust

Q: How serious is black smoke from exhaust?

Severity is rated Medium. Replace the air filter first. If it doesn't help, get the MAF cleaned or replaced. Long-term rich running damages the catalytic converter.

Black smoke means the engine is burning too much fuel — a 'rich' condition.

Severity: Medium

What to Do Right Now

Replace the air filter first. If it doesn't help, get the MAF cleaned or replaced. Long-term rich running damages the catalytic converter.

Common Causes

Clogged air filter: Restricted air = rich mixture = black smoke. Cheapest fix. Shop air filter
Faulty mass airflow sensor: Bad MAF readings make the engine dump extra fuel. Shop mass airflow sensor
Stuck-open fuel injector: Drowns the cylinder in fuel. Shop fuel injectors
Bad O2 sensor: Bad readings cause incorrect fuel trim. Shop oxygen sensor
Failing fuel pressure regulator: Sends too much fuel to the injectors. Shop fuel pressure regulator