P0506 Code Meaning and Next Steps

First checks take 10 to 20 minutes for the first checks. No special tools are usually needed for the first checks.

Can you keep driving?

Stop driving if any of these apply

!The engine stalls repeatedly or will not stay running at idle.
!The vehicle loses power badly enough that it becomes unsafe to continue.

If the light is steady and the vehicle still drives normally: Often yes for a short time, but idle quality should be watched closely.

What to check first

Step-by-step checks

1
Free - no tools
Check whether idle drops below normal when the engine is warm or when accessories switch on
2
Free - no tools
Inspect the throttle body and intake hose for carbon buildup or restrictions
3
Basic tool needed
Look for vacuum leaks that would upset idle air balance
4
Basic tool needed
If the vehicle has an idle relearn procedure, confirm whether it was lost after battery work
5
Basic tool needed
If scan data is available, compare actual idle speed with the commanded idle target

If the code returns

-If cleaning or relearning improves the idle, the fault was likely air-path related.
-If the code returns, check for hidden vacuum leaks or a throttle that is sticking under heat.
-If the engine also misfires, repair that first because it can pull idle lower by itself.

Background

What this code means

P0506 is a generic OBD-II idle-control code.

These codes usually mean the ECU is not able to keep idle speed where it wants it, either because the air path is off, the throttle body is dirty, or a related sensor signal is not believable.

The engine may idle rough, dip low at stops, or stall when the air conditioning or steering load changes.

Diagnosis

Common causes

Most common

Dirty throttle body

Carbon can reduce airflow at idle.

Common

Vacuum leak

A leak can make the ECU struggle to hold a stable idle target.

Common

Idle relearn lost

Battery disconnection or cleaning can throw off idle control.

Possible

Sticking idle control path

The hardware may not be moving as the ECU expects.

Avoid these mistakes

What not to do

xDo not replace the throttle body first if the intake is dirty, leaking, or obviously sticking.
xDo not ignore vacuum leaks, because they can mimic a bad idle-control part.

Parts

Parts that may need replacing

PartTypical costNotes

Throttle body cleaning or service$10-$120Often the right first step if the throttle is dirty.

Vacuum hose or intake repair$10-$120Worth checking if a leak is found.

Throttle body or idle control valve$60-$350Relevant when cleaning and relearn do not fix the low idle.

Related OBD codes

P0505

P0505 usually means the idle control system is not holding normal idle speed.

P0507

P0507 usually means the idle speed is higher than the ECU expects.

P0171

P0171 usually means bank 1 is running too lean.

P0300

P0300 usually means the engine is detecting random or multiple-cylinder misfires.

Source notes

Generic OBD-II (SAE J1979 / ISO 15031-5). P0506 was expanded around common low-idle faults, including throttle contamination, vacuum leaks, and lost idle adaptation.

This guide is written as a generic multi-make reference, so bulletin history, sensor locations, and repair order can still change by manufacturer and engine family.

This is generic OBD-II guidance and should not override vehicle-specific service information. Exact diagnosis and repair steps vary by make, engine family, and model year.

Last reviewed: 2026-04-10

Reference: Open reference

P0506 - P0506 Usually Means the Idle Speed Is Lower Than the Ecu Expects