Port and Direct Injection System Imbalance
2019-2024 BMW 3 Series G20 2.0L I4 Turbo B48
Description
In dual-injection systems (combined port and direct injection), the balance between PFI and GDI fueling is incorrect.
Symptoms
- Check Engine Light
- Rough idle
- Knock or ping under load
- Poor emissions
- Fuel economy reduced
- Cold start misfires
Common Causes
- Port injector partial blockage
- GDI injector drift
- Fuel pressure imbalance between systems
- PCM fuel strategy calibration error
- Intake runner flap affecting port injection
Diagnostic Steps
- Compare port vs direct injection fuel trim data
- Test individual port injector flow
- Test GDI injector flow rates
- Monitor knock sensor activity
- Check intake runner valve operation
Repair Notes
Clean or replace affected injectors. Recalibrate fuel split strategy if software update is available. Check intake runner valves.
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
P3656 on Other Vehicles
Common Questions
What does code P3656 mean on a 2019-2024 BMW 3 Series G20?
P3656 stands for "Port and Direct Injection System Imbalance". In dual-injection systems (combined port and direct injection), the balance between PFI and GDI fueling is incorrect.
What are the symptoms of P3656 on a BMW 3 Series G20?
Common symptoms of P3656 include: Check Engine Light, Rough idle, Knock or ping under load, Poor emissions, Fuel economy reduced, Cold start misfires.
What causes P3656 on a 2019-2024 BMW 3 Series G20?
Common causes of P3656 include: Port injector partial blockage, GDI injector drift, Fuel pressure imbalance between systems, PCM fuel strategy calibration error, Intake runner flap affecting port injection.