P0499

EVAP System Vent Valve Control Circuit High

Q: Is it safe to drive with P0499?

Yes. The EVAP vent valve only manages fuel vapour, so the engine runs normally. Repair it to clear the light and pass emissions.

Q: Can I just clear P0499?

It returns the next time the ECM runs its EVAP test unless the vent valve or its wiring is fixed.

EVAP system Generic OBD-II Low

What it means

P0499 means the ECM sees a high voltage in the control circuit of the evaporative emission (EVAP) vent valve, which usually points to an open circuit. That valve lets fresh air into the charcoal canister during purge so trapped fuel vapours can be burned in the engine. The fault is an emissions-system issue only — the engine runs normally — so it mainly affects the check-engine light and emissions readiness.

Low

Can I keep driving? Safe to keep driving — this is an emissions/vapour-control fault that won't affect how the engine runs.

Real-world scan data

Seen in

scans in the past year

Found in

<0.1%

of scans

<0.1%

of scans that found faults

Figures reflect only diagnostic scans recorded through our own apps and tools. Cars are typically scanned because a symptom or warning light prompted it, so these counts describe our scan records — not the incidence of faults in any model, and not the quality, reliability, or safety of any vehicle. No comparison between manufacturers or models is implied. All trademarks belong to their respective owners; no affiliation or endorsement is implied.

Common symptoms

What you'll notice

Check-engine light on
Usually no change in how the car drives
May fail an emissions or EVAP readiness test
Occasionally a faint fuel-vapour odour

Common causes

Most likely first

Faulty EVAP vent valve solenoidLikely
Open or high-resistance wiring/connector in the vent valve control circuit (a high signal often means an open)Common
Corroded or loose connection at the vent valveCommon
Engine control module (ECM) fault (rare)Less often

How to diagnose & fix

Work through it in order

Read freeze-frame data and confirm the code with a scan tool.
Locate the EVAP vent valve (usually near the charcoal canister) and inspect its connector and wiring for an open.
Measure the vent valve solenoid's resistance against spec.
Replace the vent valve if the solenoid or circuit is faulty.
Consider the ECM only after wiring and the valve test good. Clear and re-test.

FAQ

Quick answers

Is it safe to drive with P0499?+

Yes. The EVAP vent valve only manages fuel vapour, so the engine runs normally. Repair it to clear the light and pass emissions.

Can I just clear P0499?+

It returns the next time the ECM runs its EVAP test unless the vent valve or its wiring is fixed.

Read & clear P0499 yourself

Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.

▶ Get it on Google Play

✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX