Error code

OBD2 P0499

OBD2P0499
Diagnostic Trouble Code· Standard OBD-II fault code read from the vehicle's onboard diagnostics.

What it means

Evaporative Emission System Vent Valve Control Circuit High.

Severity

moderateIt is not recommended to drive the car with this code as it poses safety risks due to potential fuel vapor leaks and engine malfunction.

Summary

P0499 indicates an issue with the evaporative emission system's vent valve control circuit being in a high state, typically due to wiring issues or a faulty vent valve.

Symptoms

  • Illuminated warning light
  • Fuel tank cannot be filled to capacity
  • Strong fuel odor
  • Driveability issues if the engine is starved of fuel

Common Causes

  • Defective EVAP vent valve
  • Burnt, damaged, shorted, or corroded wiring and connectors
  • Failed PCM (rare)

Diagnosis

  1. Inspect all associated wiring and connectors for damage.
  2. Perform resistance, ground, and continuity checks on wiring.
  3. Manually activate the vent valve solenoid using a scanner if possible.
  4. Test the vent valve control circuit with battery voltage applied directly to the solenoid.

Fixes

  • Replace the EVAP vent valve— $70-$200
  • Repair or replace damaged wiring and connectors

FAQ

How do I prevent common mistakes when repairing P0499?

Ensure to resolve any preceding codes before diagnosing P0499. Also, inspect the vent valve's air intake for restrictions.

What should I do if other EVAP system codes are present with P0499?

Diagnose and fix these codes in the order they were stored to avoid misdiagnosis.

View source

Not affiliated with OBD2. Answer summarized from the manufacturer's manual linked above; consult that source for the authoritative procedure.

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