System Too Rich Bank 1
2019-2024 BMW 3 Series G20 2.0L I4 Turbo B48
Description
The long-term fuel trim for Bank 1 has exceeded the negative limit, indicating the engine is running rich. The PCM is subtracting fuel to compensate.
Symptoms
- Check Engine Light
- Black exhaust smoke
- Poor fuel economy
- Rough idle
- Fuel smell
- Fouled spark plugs
Common Causes
- Leaking fuel injector
- High fuel pressure
- Faulty O2 sensor reading lean
- Stuck-open EVAP purge valve
- Saturated charcoal canister
- Faulty MAF sensor (underreporting)
Diagnostic Steps
- Check fuel trim values
- Test fuel pressure
- Check for leaking injectors (fuel pressure drop test)
- Inspect EVAP purge valve
- Test MAF sensor
- Inspect spark plugs
Repair Notes
Check fuel injectors for leaks. Test fuel pressure regulator. Inspect EVAP system.
Related Codes
Other Powertrain Codes
- P0001Fuel Volume Regulator Control Circuit/Open
- P0002Fuel Volume Regulator Control Circuit Range/Performance
- P0003Fuel Volume Regulator Control Circuit Low
- P0004Fuel Volume Regulator Control Circuit High
- P0010Intake Camshaft Position Actuator Circuit/Open Bank 1
- P0011Intake Camshaft Position Timing Over-Advanced Bank 1
- P0012Intake Camshaft Position Timing Over-Retarded Bank 1
- P0013Exhaust Camshaft Position Actuator Circuit/Open Bank 1
- P0014Exhaust Camshaft Position Timing Over-Advanced Bank 1
- P0015Exhaust Camshaft Position Timing Over-Retarded Bank 1
P0172 on Other Vehicles
Common Questions
What does code P0172 mean on a 2019-2024 BMW 3 Series G20?
P0172 stands for "System Too Rich Bank 1". The long-term fuel trim for Bank 1 has exceeded the negative limit, indicating the engine is running rich. The PCM is subtracting fuel to compensate.
What are the symptoms of P0172 on a BMW 3 Series G20?
Common symptoms of P0172 include: Check Engine Light, Black exhaust smoke, Poor fuel economy, Rough idle, Fuel smell, Fouled spark plugs.
What causes P0172 on a 2019-2024 BMW 3 Series G20?
Common causes of P0172 include: Leaking fuel injector, High fuel pressure, Faulty O2 sensor reading lean, Stuck-open EVAP purge valve, Saturated charcoal canister, Faulty MAF sensor (underreporting).