P0479 Exhaust Pressure Control Valve Intermittent

Definition: The OBD-II code P0479 indicates a problem with the exhaust pressure control valve, specifically that its operation is intermittent. This means that the valve may not be consistently opening or closing as required by the engine control module (ECM).

Description: The exhaust pressure control valve is responsible for regulating exhaust backpressure to optimize engine performance and emissions. When this component does not function properly, it can lead to issues such as reduced fuel efficiency, increased emissions, and potential damage to other engine components.

p0479 – Exhaust Pressure Control Valve Intermittent

Typical Severity: Moderate

Common Causes

P0479 – Exhaust Pressure Control Valve Intermittent

Common Causes:

• Faulty exhaust pressure control valve
• Wiring or connector issues in the exhaust pressure control valve circuit
• Corrosion or poor connection at the exhaust pressure control valve connector
• Exhaust system leaks affecting pressure readings
• Software glitches in the engine control module (ECM)

Common Misdiagnosis

OBD2 Code: P0479

Description: Exhaust Pressure Control Valve Intermittent

Common Misdiagnosis: Replacing the exhaust pressure control valve without checking for wiring issues or sensor malfunctions.

Common Diagnostic Steps

OBD2 Code: P0479

Description: Exhaust Pressure Control Valve Intermittent

• Check for any exhaust leaks or restrictions that may affect the pressure readings.
• Inspect the exhaust pressure control valve and its related components for damage or wear.
• Test the electrical connections and wiring to the exhaust pressure control valve for continuity and proper voltage supply.
• Use a scan tool to monitor live data from the exhaust pressure sensor to check for irregularities in readings.
• Perform a visual inspection of vacuum lines connected to the control valve for cracks or disconnections.
• Verify that there are no other codes present that could be affecting the operation of the exhaust pressure system.
• If equipped, test the functionality of any associated sensors, such as MAP (Manifold Absolute Pressure) or BARO (Barometric Pressure) sensors, which can influence exhaust pressure readings.