Your 2022 Seltos has a steady check engine light with P0172, indicating the engine is running too rich—too much fuel relative to air. While less dramatic than a flashing light, this condition wastes fuel, fouls spark plugs, and can damage the catalytic converter over time.
What P0172 Means
The P0172 code indicates "System Too Rich (Bank 1)." The engine computer is detecting that it needs to remove significant fuel to maintain proper air-fuel ratio. Something is either adding extra fuel or reducing airflow.
Symptoms of Rich Running
- Steady check engine light
- Decreased fuel economy
- Black soot from exhaust
- Fuel smell from tailpipe
- Rough idle possible
- Spark plugs may foul prematurely
Common Causes
- Leaking fuel injector - Injector not closing fully, dripping fuel
- Faulty O2 sensor - Reporting incorrect readings
- Dirty air filter - Severely restricting airflow
- MAF sensor contamination - Over-reporting airflow
- Fuel pressure regulator - Stuck allowing too much pressure
- EVAP purge valve stuck open - Dumping fuel vapors into intake
Fuel Trim Interpretation
The scan tool shows fuel trims as negative percentages when running rich. Long-term fuel trim (LTFT) below -10% confirms the computer is actively reducing fuel. Values below -20% indicate a significant rich condition.
Diagnostic Steps
- Check fuel trim data—confirm rich condition
- Inspect air filter—replace if heavily restricted
- Check for fuel smell at injectors
- Test O2 sensor readings front and rear
- Monitor MAF sensor readings against specifications
- Test fuel pressure for excessive reading
Repair Costs
- Air filter: $20-$50
- O2 sensor: $150-$300
- Fuel injector: $150-$350
- MAF sensor: $150-$350
- Fuel pressure regulator: $200-$400
- EVAP purge valve: $100-$250