P0506

Severity: Medium

Idle Control System RPM lower Than Expected

Last updated: July 2026

System

Powertrain

Subsystem

Vehicle Speed, Idle & Auxiliary Inputs

Code Type

Generic (SAE)

What does P0506 mean?

P0506 is a generic (SAE) powertrain diagnostic trouble code. It is defined as "Idle Control System RPM lower Than Expected". It falls under the vehicle speed, idle & auxiliary inputs area of the vehicle’s powertrain system, and has the same core meaning across most makes and models.

When is P0506 set?

The onboard diagnostic system sets P0506 when it detects a condition matching "idle control system rpm lower than expected" in the vehicle speed, idle & auxiliary inputs circuit or system. When the fault is confirmed, the module stores the code and, in most cases, turns on a warning light.

This code is generally moderate. The vehicle is often still drivable, but the underlying fault should be diagnosed before it leads to further problems.

Common symptoms

Check engine light (MIL) illuminated
Rough running, hesitation or loss of power
Increased fuel consumption
Difficulty starting or stalling

Possible causes

A failing or contaminated sensor in the affected circuit
Wiring, connector or ground problems
Vacuum, intake or exhaust leaks
A worn or failing mechanical component
Occasionally, a fault in the control module itself

What to check first

Scan for all stored and pending codes and note the freeze-frame data
Inspect the wiring and connectors for the affected circuit
Check for related leaks, loose components or obvious damage
Test the relevant sensor and its reference/ground with a meter
Clear the code and retest to see whether it returns

Frequently asked questions

What does the P0506 code mean?

P0506 means "Idle Control System RPM lower Than Expected". It is a generic powertrain trouble code in the vehicle speed, idle & auxiliary inputs area.

Is it safe to drive with a P0506 code?

The vehicle is often still drivable with this code, but you should have it diagnosed soon so a moderate fault does not turn into a larger one.

How do I fix a P0506 code?

There is no single fix. Start by confirming the code with a scan tool, then work through the likely causes and checks above — inspecting wiring, connectors and the relevant components before replacing any parts. On most vehicles, confirm the diagnosis before repairs.

Can I clear the P0506 code myself?

You can clear the code with an OBD-II scan tool, but if the underlying fault is still present it will usually return. Clearing without repair is only useful to confirm whether the fault is active.

Related codes

P0507

Idle Control System RPM higher Than Expected

P0505

Idle Control System Malfunction

P0510

Closed Throttle Position Switch Malfunction

Important

This information is provided for general reference only. It is not repair advice and may not apply to every make or model. Manufacturer-specific codes can differ. Always confirm a diagnosis with a scan tool and, where needed, a qualified technician before replacing parts.