P0172Medium urgency
System Too Rich (Bank 1)
Fuel System · Air/Fuel Mixture
⚠️ Drive with caution — rich conditions can foul spark plugs.
What this means
Bank 1 is running rich — too much fuel relative to air. The ECU is hitting its correction limits. Common causes: stuck-open fuel injector, faulty MAF sensor, or leaking fuel pressure regulator.
Likely causes
- Faulty or dirty MAF sensorMost common
- Stuck-open fuel injectorCommon
- Fuel pressure regulator failureCommon
Estimated repair cost
MAF sensor cleaning/replace$100 – $300
Fuel injector service$150 – $400
Fuel pressure regulator$150 – $350
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Frequently asked questions
What does P0172 mean?
Bank 1 is running rich — too much fuel relative to air. The ECU is hitting its correction limits. Common causes: stuck-open fuel injector, faulty MAF sensor, or leaking fuel pressure regulator.
Is P0172 serious?
Drive with caution — rich conditions can foul spark plugs.
How much does it cost to fix P0172?
Repair costs for P0172 range from $100 – $300 depending on the root cause and your vehicle.
Can I drive with P0172?
You can drive short distances but should have it repaired within 1-2 weeks to prevent further damage.