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Engine-Codes – GMC – P0499 GMC

P0499 GMC Code - Evaporative Emission System Vent Valve Control Circuit High

Quick Answer

The P0499 GMC code refers to the Evaporative Emission System Vent Valve Control Circuit High. Common causes include Faulty vent valve, Wiring issues in the control circuit, Malfunctioning control module. Severity is Low - monitor the vehicle and repair when practical. The vehicle can usually be driven if no severe symptoms are present, but symptoms should be checked before extended driving.

What it means
P0499 GMC indicates Evaporative Emission System Vent Valve Control Circuit High.
Common causes
Common causes include Faulty vent valve, Wiring issues in the control circuit, Malfunctioning control module.
Severity
Low - monitor the vehicle and repair when practical.
Can I drive?
The vehicle can usually be driven if no severe symptoms are present, but symptoms should be checked before extended driving.
What is this?
Table of contents Created and updated by William Orellana on Sep 09, 2024
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Code P0499 GMC Description

The P0499 GMC code refers to the Evaporative Emission System Vent Valve Control Circuit High. This means that there is a malfunction in the control circuit of the vent valve that manages the flow of fuel vapor from the fuel tank to the engine. This can lead to issues with the vehicle's emissions system, as well as potentially affecting overall engine performance.

OBDII Code P0499 GMC - Evaporative Emission System Vent Valve Control Circuit High
P0499 GMC Code - Evaporative Emission System Vent Valve Control Circuit High

Common Causes of P0499 GMC

  1. Faulty vent valve
  2. Wiring issues in the control circuit
  3. Malfunctioning control module
  4. Loose electrical connections
  5. Corrosion in the system components

Symptoms of P0499 GMC

  1. Check Engine Light illuminated on the dashboard
  2. Failed emissions test
  3. Reduced fuel efficiency
  4. Rough idling or stalling
  5. Strong fuel odor around the vehicle

How to Fix P0499 GMC

  1. Use an OBD-II scanner to confirm the P0499 code and diagnose the specific cause of the issue.
  2. Inspect the vent valve and control circuit for any visible damage or issues.
  3. Test the electrical connections and wiring for continuity and proper voltage.
  4. Replace the vent valve if it is found to be faulty.
  5. Clear the diagnostic trouble codes and test drive the vehicle to ensure the issue has been resolved.

Cost to Fix P0499 GMC

The typical repair costs for addressing a P0499 GMC code can range from $100 to $300, depending on the specific cause of the issue and the cost of parts and labor. Keep in mind that diagnosis time and labor rates at auto repair shops can vary, so it's advisable to check with local shops for a more accurate estimate. Additionally, factors such as the vehicle make and model, as well as the engine type, can also impact the overall cost of repairs.

What does this mean?

Tech Notes for P0499 GMC

















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Information for Specific GMC Models

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 P0499 GMC Code

1. What does the OBDII code P0499 mean on a GMC vehicle?

P0499 indicates an issue with the evaporative emission (EVAP) system vent valve control circuit, specifically that the circuit voltage is higher than expected.

2. What are the common symptoms of code P0499 on a GMC?

Symptoms may include an illuminated Check Engine Light, difficulty refueling due to tank pressure issues, a noticeable fuel odor, or a failed emissions test.

3. What causes the P0499 code to appear on a GMC vehicle?

Common causes include a faulty EVAP vent valve, damaged or corroded wiring in the vent valve circuit, a defective control module, or a clogged EVAP system vent.

4. How is the P0499 code diagnosed on a GMC?

A technician will use an OBDII scanner to confirm the code, inspect the vent valve and wiring for damage, and test the voltage and continuity of the EVAP vent valve circuit.

5. Can I still drive my GMC with a P0499 code?

While the vehicle may still be drivable, ignoring this code can lead to increased emissions or fuel system issues. It's best to address the problem promptly.

6. How do I fix the P0499 code on a GMC vehicle?

Repairs may include replacing the EVAP vent valve, repairing damaged wiring or connectors, cleaning the vent system, or updating the vehicle's ECU if necessary.

7. How much does it cost to fix the P0499 code on a GMC?

Repair costs can range from $100 to $300, depending on whether the vent valve needs replacement or if wiring repairs are required.

8. Can a loose gas cap cause the P0499 code on a GMC?

No, a loose gas cap typically triggers different EVAP-related codes, such as P0455 or P0442, but it is not directly related to the P0499 code.

9. What tools are needed to troubleshoot the P0499 code on a GMC?

Tools may include an OBDII scanner, a multimeter to check voltage and continuity, and basic hand tools for inspecting and replacing components.

10. Will clearing the P0499 code with a scanner fix the problem?

Clearing the code will turn off the Check Engine Light temporarily, but the underlying issue must be resolved to prevent the code from returning.

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