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P0479 Ford Code - Exhaust Pressure Control Valve Intermittent

Quick Answer

The P0479 code for Ford vehicles indicates a problem with the Exhaust Pressure Control Valve (EPCV) being intermittent. Common causes include Faulty EPCV: The most common cause of the P0479 code is a malfunctioning or failed Exhaust Pressure Control Valve, Wiring Issues: Corrosion, damage, or loose connections in the wiring harness connected to the EPCV can also trigger this code, Vacuum Leaks: Any leaks in the vacuum system that affects the EPCV's operation can lead to this error code. Severity is Moderate - service should be scheduled soon. The vehicle may still be drivable for short trips if it runs normally, but avoid hard driving and repair it soon.

What it means
P0479 Ford indicates Exhaust Pressure Control Valve Intermittent.
Common causes
Common causes include Faulty EPCV: The most common cause of the P0479 code is a malfunctioning or failed Exhaust Pressure Control Valve, Wiring Issues: Corrosion, damage, or loose connections in the wiring harness connected to the EPCV can also trigger this code, Vacuum Leaks: Any leaks in the vacuum system that affects the EPCV's operation can lead to this error code.
Severity
Moderate - service should be scheduled soon.
Can I drive?
The vehicle may still be drivable for short trips if it runs normally, but avoid hard driving and repair it soon.
What is this?
Table of contents Created and updated by William Orellana on Sep 08, 2024
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Code P0479 Ford Description

The P0479 code for Ford vehicles indicates a problem with the Exhaust Pressure Control Valve (EPCV) being intermittent. The EPCV is a crucial component in the vehicle's exhaust system, responsible for regulating the pressure in the exhaust system. When this valve malfunctions or operates intermittently, it can lead to a variety of issues affecting the vehicle's performance, emissions, and overall efficiency.

OBDII Code P0479 Ford - Exhaust Pressure Control Valve Intermittent
P0479 Ford Code - Exhaust Pressure Control Valve Intermittent

Common Causes of P0479 Ford

  1. Faulty EPCV: The most common cause of the P0479 code is a malfunctioning or failed Exhaust Pressure Control Valve.
  2. Wiring Issues: Corrosion, damage, or loose connections in the wiring harness connected to the EPCV can also trigger this code.
  3. Vacuum Leaks: Any leaks in the vacuum system that affects the EPCV's operation can lead to this error code.
  4. Carbon Buildup: Accumulated carbon deposits on the EPCV or surrounding components can hinder its proper operation.
  5. Exhaust System Blockages: Obstructions in the exhaust system, such as clogs or restrictions, can cause pressure irregularities triggering the P0479 code.

Symptoms of P0479 Ford

  1. Check Engine Light: The most common symptom associated with the P0479 code is the illumination of the Check Engine Light on the vehicle's dashboard.
  2. Reduced Engine Performance: A malfunctioning EPCV can lead to reduced engine performance, including decreased power and acceleration.
  3. Increased Emissions: Due to improper exhaust pressure regulation, the vehicle may produce higher emissions than normal, potentially leading to a failed emissions test.
  4. Rough Idle: An intermittent EPCV can cause the engine to idle roughly or inconsistently.
  5. Fuel Efficiency Issues: Drivers may notice a decrease in fuel efficiency as a result of the EPCV malfunctioning.

How to Fix P0479 Ford

  1. Diagnose the Issue: Use a professional OBD-II scanner to read and interpret the P0479 code, and perform a thorough inspection of the EPCV, wiring, and related components.
  2. Replace the EPCV: If the Exhaust Pressure Control Valve is found to be faulty, replace it with a new OEM or quality aftermarket part.
  3. Repair Wiring: Address any wiring issues by repairing or replacing damaged wires, connectors, or terminals.
  4. Clean Exhaust System: Remove any carbon buildup in the exhaust system, including the EPCV, to ensure proper operation.
  5. Clear Codes and Test Drive: After completing the repairs, clear the error codes from the vehicle's computer, and test drive the vehicle to ensure the issue has been resolved.

Cost to Fix P0479 Ford

The typical cost to repair the Exhaust Pressure Control Valve Intermittent issue can vary depending on the make and model of the Ford vehicle, as well as the location and labor rates of the auto repair shop. In general, replacing the EPCV and addressing any related wiring or cleaning needs can range from $200 to $500 for parts and labor. However, it's essential to obtain a personalized estimate from a qualified mechanic or repair shop to get an accurate cost for this specific repair. Keep in mind that diagnostic time and hourly labor rates can vary, affecting the total repair cost.

What does this mean?

Tech Notes for P0479 Ford

Check the Exhaust Back Pressure Valve (EBPV) butterfly valve is opening and closing freely and not sticking. If it seems to move freely you can then check the connector and circuit for the EBPV solenoid.

When is the Code Detected?

Problems with either the Exhaust Back Pressure (EBP) Device or the tube between the exhaust manifold and the EBP sensor can be detected during the exhaust back pressure step test, in which the Engine Control Module (ECM) commands and then measures a specific preprogrammed pressure and then measures time for pressure decay during the engine running test.

If the ECM detects an Exhaust Back Pressure (EBP), Engine Oil Temperature (EOT) or Intake Air Temperature (IAT) sensor fault it will disable the exhaust back pressure regulator.

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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.

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