Question 1

What does P0172 mean?

Accepted Answer

P0172 - System Too Rich (Bank 1). Engine running too rich on bank 1 — too much fuel or not enough air.

Question 2

What are the symptoms of P0172?

Accepted Answer

Check engine light, Rich exhaust smell, Black smoke, Poor fuel economy, Spark plug fouling, Rough idle

Question 3

What causes P0172?

Accepted Answer

Leaking fuel injector, Stuck-open purge valve, Faulty fuel pressure regulator, Dirty air filter, Failed MAF sensor reading low, Faulty O2 sensor

Question 4

How much does it cost to fix P0172?

Accepted Answer

Typical repair cost: $50-$600. Check fuel trims. If STFT is very negative (-15% or more), check for leaking injector and stuck-open EVAP purge valve.

P0172 — System Too Rich (Bank 1)

Don't guess — diagnose P0172 the right way