P0506

What it means

P0506 on an Audi means the engine control unit saw the idle speed sitting lower than the target it was commanding, and could not correct it within the allowed limits. This is commonly linked to unmetered air leaks, a dirty or sticking throttle body or idle control component, or an extra load such as the power steering pressure switch. The exact idle control hardware depends on the model and engine, as most modern Audis use an electronic throttle body rather than a separate idle air control motor.

Symptoms

• Low, rough or hunting idle
• Engine stalling or nearly stalling when coming to a stop
• Engine management light on
• Idle dipping when steering is turned or electrical loads are switched on
• Hesitation or poor throttle response at very low revs

Possible causes

• Intake manifold or vacuum hose leak, including split hoses, cracked intake pipework or a leaking manifold gasketlikely
• Carbon or dirt build-up in the throttle body and its air passageslikely
• Sticking or faulty idle air control motor or electronic throttle body actuator, depending on model and enginepossible
• Faulty power steering pressure switch or sensor causing the control unit to add the wrong load compensationpossible
• Crankcase breather or positive crankcase ventilation fault causing an unmetered air leak or incorrect flowpossible
• Wiring or connector damage to the throttle body or idle control circuitrare
• Engine mechanical or fuelling issue such as worn ignition parts or a blocked injector reducing idle stabilityrare

How to diagnose

1. Read all stored and pending codes and review the freeze frame data, noting engine temperature, load and idle speed when the fault was set
2. Visually inspect vacuum hoses, intake pipework, breather hoses and connectors for splits, loose clips and perishing
3. Check live data for idle speed against target, short and long term fuel trims, and throttle angle at idle; a large positive trim points towards an air leak
4. Perform a smoke test of the intake system to locate leaks
5. Inspect the throttle body for carbon build-up and check that the plate moves freely and smoothly
6. Check the throttle body wiring and connector, then carry out a throttle body adaption or basic setting using diagnostic equipment, following the model-specific procedure
7. Check the power steering pressure switch or sensor signal in live data and test its wiring, noting that the layout varies by model
8. Check ignition components and injector operation if no air or throttle fault is found

How to fix

• Repair or replace leaking vacuum hoses, intake pipework, breather components or manifold gaskets
• Clean the throttle body using a suitable cleaner as per the manufacturer's procedure, then carry out the throttle adaption
• Replace the throttle body or idle control actuator if it sticks or fails its tests
• Replace a faulty power steering pressure switch or sensor and repair any damaged wiring
• Repair damaged wiring or connectors, then clear the codes and confirm the idle holds steady across a drive cycle

Can I keep driving?

This code for other makes

• P0506GenericIdle Control System RPM - Lower Than Expected

Nearby codes

• P0505AudiDefective Idle Air Control Motor, Intake Manifold Vacuum leaks, Carbon buildup in the Throttle Body air passages
• P0507AudiDefective or sticking Idle Air Control Motor, Intake Manifold Vacuum leaks, Carbon buildup in the Throttle Body air passages, Defective Coolant Temperature Sensor, Defective Charging System/Alternator, Defective Power Steering Pressure Switch