P0506moderate severityPowertrain
Idle Air Control System RPM Lower Than Expected
on 2002 BMW 540iT E39 4.4L V8 M62 Touring · RWD
What this code means
The idle speed is consistently below the target RPM.
Symptoms
- Low idle speed
- Stalling
- Rough idle
Common causes
- Carbon buildup in throttle body
- Vacuum leak
- Faulty IAC valve
- Low fuel pressure
- EGR valve stuck open
Diagnostic steps
- Clean throttle body
- Check for vacuum leaks
- Test IAC valve
- Test fuel pressure
- Check EGR valve
Repair notes
Clean throttle body and IAC. Check for vacuum leaks.
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