AutoCodes – Ford – P1504 1999 Ford F150

P1504 1999 Ford F150 Code - Intake Air Control Circuit Malfunction

Quick Answer

The Idle Air Control Valve (IACV) valve assembly controls the engine idle speed and provides a dashpot function. Common causes include Faulty Idle Air Control Valve, Idle Air Control Valve harness is open or shorted, Idle Air Control Valve circuit poor electrical connection. 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: P1504 1999 Ford F150 indicates Intake Air Control Circuit Malfunction.
Common causes: Common causes include Faulty Idle Air Control Valve, Idle Air Control Valve harness is open or shorted, Idle Air Control Valve circuit poor electrical connection.
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 6,963

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Intermediate (2 / 3)

What is this?

Table of contents Created and updated by William Orellana on Aug 25, 2019

Description
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
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Code P1504 1999 Ford F150 Description

The Idle Air Control Valve (IACV) valve assembly controls the engine idle speed and provides a dashpot function. The IAC valve assembly meters intake air around the throttle plate through a bypass within the IAC valve assembly and throttle body. The Powertrain Control Module (PCM) determines the desired idle speed or bypass air and signals the IAC valve assembly through a specified duty cycle. The IAC valve responds by positioning the IAC valve to control the amount of bypassed air. The PCM monitors engine RPM and increases or decreases the IAC duty cycle in order to achieve the desired RPM.

OBDII Code P1504 1999 Ford F150 - Intake Air Control Circuit Malfunction - AutoCodes.com — P1504 1999 Ford F150 Code - Intake Air Control Circuit Malfunction

What does this mean?

What are the Possible Causes of the DTC P1504 1999 Ford F150?

Faulty Idle Air Control Valve
Idle Air Control Valve harness is open or shorted
Idle Air Control Valve circuit poor electrical connection
Faulty Powertrain Control Module (PCM)

How to Fix the DTC P1504 1999 Ford F150?

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

The Idle Air Control solenoid resistance is from 6 to 13 ohms.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P1504 1999 Ford F150 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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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.

Frequently Asked Questions about P1504 1999 Ford F150 Code

1. What are the common symptoms of OBDII code P1504 on a 1999 Ford F150?

- Common symptoms include rough idling, stalling, poor engine performance, and possible engine hesitation.

2. What can cause the OBDII code P1504 on a 1999 Ford F150?

- The code P1504 typically indicates an issue with the intake air control circuit, which can be caused by a faulty idle air control valve, wiring issues, or a vacuum leak.

3. How can I diagnose the intake air control circuit malfunction causing OBDII code P1504 on my 1999 Ford F150?

- You can start by checking the idle air control valve for proper operation, inspecting the wiring for any damage, and using a vacuum gauge to identify potential leaks.

4. Can a dirty or clogged air filter trigger the OBDII code P1504 on a 1999 Ford F150?

- While a dirty or clogged air filter can affect engine performance, it is not a direct cause of the intake air control circuit malfunction indicated by code P1504.

5. What are some repair tips for fixing the intake air control circuit malfunction causing OBDII code P1504 on a 1999 Ford F150?

- Repair tips include cleaning or replacing the idle air control valve, repairing any damaged wiring, and addressing any vacuum leaks in the intake system.

6. Will driving with the OBDII code P1504 on a 1999 Ford F150 cause further damage to the vehicle?

- Continuing to drive with code P1504 may lead to worsened engine performance and potential damage over time, so it is recommended to address the issue promptly.

7. Can resetting the OBDII code P1504 on a 1999 Ford F150 make it go away permanently?

- Resetting the code may temporarily clear the warning light, but if the underlying issue causing code P1504 is not fixed, the code is likely to reappear.

8. Is it safe to ignore the OBDII code P1504 on a 1999 Ford F150 if the vehicle seems to be running fine?

- Ignoring code P1504 can lead to decreased fuel efficiency, engine performance issues, and potential long-term damage, so it is not recommended to ignore the code.

9. How much does it typically cost to repair the intake air control circuit malfunction causing OBDII code P1504 on a 1999 Ford F150?

- The cost of repair can vary depending on the exact cause of the issue, but it may range from around $100 for a simple fix to a few hundred dollars for more complex repairs.

10. Can a DIY enthusiast with basic automotive knowledge fix the intake air control circuit malfunction causing OBDII code P1504 on a 1999 Ford F150?

- Depending on the specific issue, a DIY enthusiast may be able to perform basic troubleshooting and repairs like cleaning or replacing the idle air control valve, but more complex issues may require professional assistance.