P0499 EVAP vent valve control circuit high: the wire to the valve that seals the fuel vapour system is reading too high

EVAP vent control circuit high

Monitor

The reference page lists a stored code and light, sometimes with hard tank filling, but not an immediate danger, so you can usually drive while you book a check.

It gets more serious if:

  • Inspect soon: Inspect soon if you smell fuel strongly or the tank will not fill properly, because the vent may be stuck closed.

Source: how we rate severity

P0499 in short

P0499 means the computer sees a high-voltage fault in the circuit that controls the EVAP vent valve. The usual causes are a faulty vent valve or damaged or corroded wiring. You can usually drive, but hard fuelling or a fuel smell means get it checked sooner.

P0499 is the high-circuit partner of P0498. The EVAP vent valve opens to fresh air or closes for leak testing, and P0499 sets when the computer sees its control circuit stuck high. The reference page lists a defective valve, burnt or corroded wiring and, rarely, the engine computer.

GM truck owners report P0499 often. One Silverado had the EVAP valve harness connector replaced, and the light returned about 48 hours later, while an Avalanche owner calls the cause a faulty vent solenoid. Both are owner reports.

A stuck-closed vent can make the tank hard to fill, so that symptom is worth mentioning to a shop.

Most likely causes

  1. Faulty EVAP vent valve (canister vent solenoid)

    Supported by vehicle data
    Why it ranks here
    The reference page lists the valve first and an Avalanche owner names the vent solenoid. Silverado owners also report repeat P0499.
    What would change this
    Rises if the valve fails a resistance or command test. Falls if it tests normal and the harness is faulty.
    How to test the evap canister vent valve

  2. Burnt, corroded or damaged wiring or connector

    Supported by vehicle data
    Why it ranks here
    The reference page lists wiring and connectors, and a Silverado dealer replaced the valve harness connector, although the light returned, so the fix was not lasting.
    What would change this
    Rises if the connector or harness is damaged. Falls if wiring tests good or the code returns after a new connector.

What to test first

Start at step 1. Each result tells you what it means and where to go next.

  1. Read all codes and note whether P0449, P0498 or P0499 are stored together; check the gas cap is tight.

    Low riskTool: OBD-II scan tool

    • IfOnly this vent circuit code is stored

      It meansInspect the vent valve wiring next.

      Go to step 2

    • IfOther EVAP codes are stored too

      It meansSeveral EVAP faults can share one valve or harness; test the vent circuit first.

      Go to step 2

  2. Find the EVAP vent valve near the canister and the fuel tank, and look at its connector and wiring for corrosion, damage, loose pins or rodent chewing.

    Use cautionTool: flashlight

    Warning:Work under the vehicle only when it is properly supported and cool, and keep sparks and open flame away from fuel vapour.

  3. Have a shop measure the vent valve resistance and check its circuit for a short to ground or voltage, and command it with a scan tool.

    Best left to a shopTool: multimeter, bidirectional scan tool

    Warning:This is done near fuel vapour and live circuits. Let a shop do it and do not probe wires with the engine running.

Symptoms

  • Check engine light with P0499 stored
  • Light may come and go, and may also affect a remote starter on some trucks
  • Hard to fill the tank or a fuel smell Gets more serious: stop and have it checked.

Compare with: Check engine light came on after getting gas

How to fix

  1. Make sure the gas cap is tight and clear the code once to see whether it returns.

  2. Look at the vent valve connector under the vehicle for corrosion, once the vehicle is cool and supported.

Parts and cost context

  • EVAP canister vent valve:The vent valve (or canister vent solenoid) was the part owners were told to replace on GM trucks and cars. Test the circuit first. Labour varies; get a quote.

Labor varies by vehicle and shop; get a quote before you approve a repair.

Compare used part prices on PartPriceGuide

On your vehicle

Chevrolet

  • 2019–2020 · Silverado 1500

    Supported by vehicle data

    Silverado 1500 owners report repeat P0499; a dealer replaced the EVAP valve harness connector and the light returned. Owner reports only.

  • 2008 · Avalanche

    Supported by vehicle data

    A 2008 Avalanche owner reports P0499 and blames the EVAP vent solenoid. Owner report.

Chrysler

  • 2003 · PT Cruiser

    Possible — needs testing

    A 2003 Chrysler bulletin lists P0499 among false codes with a no start after key cycling. Unverified bulletin; repair not stated.

  • 1802603 (chrysler)Status unverified

    No start and MIL with false DTCs including P0498 and P0499

    2003pt-cruiser · NHTSA 10002044

    Lists P0499 among false DTCs on 2003 models with a no start after key cycling. The summary does not give the repair.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

Dodge

  • 1802603 (dodge)Status unverified

    No start and MIL with false DTCs including P0498 and P0499

    2003neon · NHTSA 10002044

    Lists P0499 among false DTCs on 2003 models with a no start after key cycling. The summary does not give the repair.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

  • P0498EVAP vent valve control circuit low: the wire to the valve that seals the fuel vapour system is reading too low

    Same system Common general cause

    P0498 is the low-voltage counterpart for the same vent valve circuit.

  • P0449EVAP vent valve circuit fault

    Same system Possible — needs testing

    P0449 also concerns the EVAP vent valve circuit. GM owner complaints report it stored together with P0498, the vent circuit low-voltage code.

All EVAP (evaporative emissions) codes

P0499 questions

Can P0499 make it hard to fill the tank?

It can. The reference page lists difficulty filling the tank as a symptom, which fits a vent that is stuck closed.

Why does P0499 keep coming back after a repair?

A Silverado owner had the harness connector replaced and the light returned in two days. Test the valve and the whole circuit, not just the connector.

Sources and review

  1. P0499 trouble code page — TroubleCodes.net
  2. NHTSA complaint ODI 10447778 — NHTSA (consumer complaint database, local flat-file cache)
  3. NHTSA complaint ODI 11561724 — NHTSA (consumer complaint database, local flat-file cache)
  4. P0498 trouble code page — TroubleCodes.net
  5. NHTSA complaint ODI 11696792 — NHTSA (consumer complaint database, local flat-file cache)
  6. NHTSA complaint ODI 11635899 — NHTSA (consumer complaint database, local flat-file cache)
  7. Chrysler 1802603: no start and MIL with false DTCs including P0498 and P0499 (2003 models) — Chrysler (FCA) (via NHTSA manufacturer communications flat file)
Last reviewed
Written by
Saurabh K.
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