AutoCodes – Infiniti – P0505 Infiniti

P0505 Infiniti Code - Idle Air Control Valve

Quick Answer

This system automatically controls engine idle speed to a specified level. Common causes include Improper idle speed, Faulty IACV-AAC valve, The IACV-AAC valve harness is open or shorted. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means: P0505 Infiniti indicates Idle Air Control Valve.
Common causes: Common causes include Improper idle speed, Faulty IACV-AAC valve, The IACV-AAC valve harness is open or shorted.
Severity: High - diagnose this code as soon as possible.
Can I drive?: Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

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Code Popularity 46,886

How popular is this code, among other codes? Medium

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

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Table of contents Created and updated by William Orellana on Jun 14, 2020

Description
Step-by-Step Diagnostic Guide
Possible Causes
How To Fix
Tech Notes ▶
Cost to Diagnose
Comments
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Code P0505 Infiniti Description

This system automatically controls engine idle speed to a specified level. Idle speed is controlled through fine adjustment of the amount of air which by-passes the throttle valve via Idle Air Control Valve IACV) and Auxiliary Air Control AAC) Valve. The IACV-AAC valve changes the opening of the air by-pass passage to control the amount of auxiliary air. This valve is actuated by a step motor built into the valve, which moves the valve in the axial direction in steps corresponding to the Engine Control Module (ECM) output signals.
One step of IACV-AAC valve movement causes the respective opening of the air by-pass passage. (i.e. when the step advances, the opening is enlarged.) The opening of the valve is varied to allow for optimum control of the engine idling speed. The crankshaft position sensor (POS) detects the actual engine speed and sends a signal to the ECM. The ECM then controls the step position of the IACV-AAC valve so that engine speed coincides with the target value memorized in ECM. The target engine speed is the lowest speed at which the engine can operate steadily. The optimum value stored in the ECM is determined by takig into consideration various engine conditions, such as during warm up, deceleration, and engine load (air conditioner, power steering and cooling fan operation).

OBDII Code P0505 Infiniti - Idle Air Control Valve - AutoCodes.com — P0505 Infiniti Code - Idle Air Control Valve

What does this mean?

What are the Possible Causes of the DTC P0505 Infiniti?

Improper idle speed
Faulty IACV-AAC valve
The IACV-AAC valve harness is open or shorted
The IACV-AAC valve circuit poor electrical connection
Faulty Engine Control Module (ECM)

How to Fix the DTC P0505 Infiniti?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What does this mean?

Code Tech Notes

P0505 Ecm IAC issue 2000 & 2001 I30 Part 1

P0505 Ecm IAC issue 2000 & 2001 I30 Part 2

P0505 Ecm IAC issue 2000 & 2001 I30 Part 3

P0505 Ecm IAC issue 2000 & 2001 I30 Part 4

P0505 Ecm IAC issue 2000 & 2001 I30 Part 5

P0505 Ecm IAC issue 2000 & 2001 I30 Part 6

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What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0505 Infiniti code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

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Information for Specific Infiniti Models

P0505 2000 Infiniti I30 — Idle Air Control Valve
P0505 2001 Infiniti I30 — Idle Air Control Valve

About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.