P0499 Fault Code

Evaporative Emission System Vent Control Circuit High

• What does that mean?
• Symptoms
• Causes
• Solutions

The P0499 fault code indicates an issue with the evaporative emission system vent control circuit, specifically that it is operating at a high voltage. This code is part of the vehicle's onboard diagnostics (OBD-II) and is triggered when the engine control module (ECM) detects a discrepancy in the system's voltage readings. The evaporative emission control system is designed to prevent fuel vapors from escaping into the atmosphere, and a malfunction in this system can lead to increased emissions and decreased fuel efficiency.

What are the symptoms of the P0499 code?

Common symptoms associated with the P0499 fault code can include:

• Check Engine Light illuminated on the dashboard
• Decreased fuel efficiency
• Difficulty starting the engine after refueling
• Fuel odor due to vapors escaping from the EVAP system
• Emissions test failure

What causes the P0499 code?

There are several potential causes for the P0499 fault code including:

• Faulty vent control valve
• Damaged or corroded wiring in the vent control circuit
• Poor electrical connections or loose connectors
• A malfunctioning ECM
• Blockages in the EVAP system

How to fix P0499?

To resolve the P0499 code, a thorough diagnostic process is essential:

• Inspect the vent control valve for proper operation and replace it if defective.
• Check all wiring and connectors in the vent control circuit for corrosion, damage, or loose connections and repair as necessary.
• Test the ECM and replace it if it is found to be the source of the problem.
• Clear the fault codes and test drive the vehicle to ensure that the problem is resolved.