P3656moderate severityPowertrain
Port and Direct Injection System Imbalance
on 2020 Mazda Mazda3 2.5L I4 · FWD
What this code means
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.
Other Powertrain codes on this vehicle
P0001
Fuel Volume Regulator Control Circuit/Open
P0002
Fuel Volume Regulator Control Circuit Range/Performance
P0003
Fuel Volume Regulator Control Circuit Low
P0004
Fuel Volume Regulator Control Circuit High
P0010
Intake Camshaft Position Actuator Circuit/Open Bank 1
P0011
Intake Camshaft Position Timing Over-Advanced Bank 1
P0012
Intake Camshaft Position Timing Over-Retarded Bank 1
P0013
Exhaust Camshaft Position Actuator Circuit/Open Bank 1
P0014
Exhaust Camshaft Position Timing Over-Advanced Bank 1
P0015
Exhaust Camshaft Position Timing Over-Retarded Bank 1