P0449 EVAP vent valve circuit fault

EVAP vent solenoid circuit

Monitor

EVAP faults let fuel vapour escape but rarely change how the car drives, and the main risk is a failed emissions test, so it is safe to drive while you arrange a fix.

It gets more serious if:

  • Inspect soon: You keep smelling raw fuel around the car, not just right after filling up
  • Stop: You see liquid fuel dripping or pooling under the car, or near the filler, tank or canister

Source: how we rate severity

P0449 in short

P0449 means the computer sees an electrical problem in the EVAP vent valve circuit. The likely causes are a failed vent valve coil or a damaged connector or wire, sometimes after dust or charcoal has got into the valve. It is generally safe to drive unless you smell or see fuel.

The vent valve is a small electric solenoid on or near the charcoal canister. The computer powers it to close the vent for leak tests, and it watches the circuit for opens and shorts.

P0449 is the electrical code. P0446 is the matching performance code, set when the valve or vent path does not behave as expected.

Because the valve sits near the tank, its connector is exposed to water, road salt and dust, so check the connector before replacing parts.

Most likely causes

These are general causes for this code across vehicles. None is specific to one make or model.

  1. Corroded, loose or damaged connector or wiring at the vent valve

    Common general cause
    Why it ranks here
    Circuit codes come from opens and shorts, and the connector under the car is the most exposed part of the circuit.
    What would change this
    Rises if the connector is green, loose or the wires are chafed.
    How to test the evap canister vent valve

  2. Vent valve coil open or shorted

    Common general cause
    Why it ranks here
    A failed solenoid coil is the other common way to break the circuit.
    What would change this
    Rises if the coil reads open or far from the service value.
    How to test the evap canister vent valve

  3. Vent valve damaged by dust intrusion

    Possible — needs testing
    Why it ranks here
    GM lists P0449 in a bulletin about dust plugging the vent solenoid on trucks in very dusty use.
    What would change this
    Rises if the valve and vent filter are full of dust.
    How to test the evap canister vent valve

  4. Charcoal from a saturated canister damaging the valve

    Possible — needs testing
    Why it ranks here
    Nissan notes that a saturated canister can shed charcoal that damages valves.
    What would change this
    Rises if you find charcoal grains in the valve or hoses.
    How to test the evap charcoal canister

What to test first

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

  1. With the engine off and cool, find the vent valve and check its connector and wires for corrosion, looseness or chafing.

    Use cautionTool: flashlight

    Warning:Fuel vapour is flammable. Work outdoors with the engine off and cool, and keep sparks, cigarettes and open flames away. Do not get under a car supported only by a jack.

  2. Command the vent valve on and off with a scan tool that has output controls, and listen or feel for a click.

    Low riskTool: scan tool with output controls

  3. Unplug the valve and measure the coil resistance, comparing it with the service information value.

    Use cautionTool: multimeter

    Warning:Fuel vapour is flammable. Work outdoors with the engine off and cool, and keep sparks, cigarettes and open flames away.

  4. Have a shop remove the valve and check it, the vent filter and the hoses for dust or charcoal.

    Best left to a shop

    Warning:Shop work on the fuel vapour system.

Symptoms

  • Check engine light on, usually with no change in how the car drives
  • Fails an emissions or smog test because of the light or an incomplete EVAP monitor
  • Persistent raw fuel smell around the car Gets more serious: stop and have it checked.
  • Liquid fuel dripping under the car Gets more serious: stop and have it checked.

How to fix

  1. Check the vent valve connector is fully seated and dry if you can reach it without lifting the car.

    Warning:Engine off and cool. Do not get under a car supported only by a jack.

  2. Stop filling once the pump clicks off the first time, to protect the canister and valves.

  3. After a repair, drive normally for several days so the monitor can re-run. Clearing codes or disconnecting the battery resets readiness, so do it shortly before an inspection only if you then complete a drive cycle.

Parts and cost context

  • EVAP canister vent valve:Usually mounted on or near the canister, close to the fuel tank. Labour varies, so get a quote.
  • EVAP charcoal canister:A canister flooded with fuel or shedding charcoal can damage new valves, so check it before replacing the valve alone.

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

Compare used part prices on PartPriceGuide

On your vehicle

Chevrolet

  • 2019–2025 · Silverado 1500

    Supported by vehicle data

    GM bulletin 23-NA-073 links P0449, P0446, P0442 and P0455 on these trucks to dust plugging the canister and vent solenoid in very dusty use. Silverado 2500 HD and 3500 HD (2020–2025) are also covered. The bulletin is on NHTSA, but whether it is still current is not verified, so it is labelled vehicle data rather than confirmed.

  • 23-NA-073Status unverified

    P0442, P0446, P0455 or P0449 from dust plugging the EVAP canister and vent solenoid

    2019–2025silverado-1500, silverado-2500-hd, silverado-3500-hd · issued · NHTSA MC-11016945

    In very dusty use, dust can get into the canister and vent solenoid and set leak or vent codes. GM prescribes adding an inline filter between the canister and its fresh-air inlet, paid by the customer, and treats the filter as a maintenance item. The same bulletin covers GMC Sierra 1500 (2019–2025) and Sierra 2500 HD/3500 HD (2020–2025); cab-and-chassis (ZW9) trucks are excluded.

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

GMC

  • 2019–2025 · Sierra 1500

    Supported by vehicle data

    The same GM bulletin (23-NA-073) covers the Sierra 1500 and the 2020–2025 Sierra 2500 HD/3500 HD for P0449, P0446, P0442 and P0455 caused by dust in the canister and vent solenoid. The bulletin is on NHTSA, but whether it is still current is not verified, so it is labelled vehicle data rather than confirmed.

  • 23-NA-073Status unverified

    P0442, P0446, P0455 or P0449 from dust plugging the EVAP canister and vent solenoid

    2019–2025silverado-1500, silverado-2500-hd, silverado-3500-hd · issued · NHTSA MC-11016945

    In very dusty use, dust can get into the canister and vent solenoid and set leak or vent codes. GM prescribes adding an inline filter between the canister and its fresh-air inlet, paid by the customer, and treats the filter as a maintenance item. The same bulletin covers GMC Sierra 1500 (2019–2025) and Sierra 2500 HD/3500 HD (2020–2025); cab-and-chassis (ZW9) trucks are excluded.

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

Volkswagen

  • 2009–2017

    Supported by vehicle data

    VW bulletin 20 17 02 lists P0449 among the codes where the N80 purge valve may be involved on 2009–2017 gasoline models (except Routan). It says to smoke test and check vacuum before replacing the valve. The bulletin is on NHTSA, but whether it is still current is not verified, so it is labelled vehicle data rather than confirmed.

    Where it is:N80 purge valve, engine bay

  • 20 17 02Status unverified

    EVAP purge valve (N80) diagnosis

    2009–2017 · issued · NHTSA MC-10125657

    For 2009–2017 gasoline Volkswagens (except Routan), lists the EVAP codes that can involve the N80 purge valve and says to smoke test the system and check vacuum before replacing the valve.

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

All EVAP (evaporative emissions) codes

P0449 questions

What is the difference between P0449 and P0446?

Both concern the vent valve. P0449 means the computer sees an electrical fault in the valve circuit. P0446 means the valve or vent path is not behaving correctly, such as a blocked vent.

Can I just replace the vent valve?

Check the connector and wiring first, because they often cause circuit codes. If the valve is full of dust or charcoal, fix the source too, or the new valve may fail.

Is it safe to keep driving?

Usually yes, as long as there is no strong fuel smell and no fuel dripping. Most makers advise getting it fixed when it is convenient. A strong fuel smell means get it checked soon, and dripping fuel means stop and do not drive.

Sources and review

  1. Frequently Asked Questions on On-Board Diagnostics (EPA 420-F-97-003) — US EPA ,
  2. On-Board Diagnostic II (OBD II) Systems Fact Sheet — California Air Resources Board ,
  3. EVAP: The Phantom Emissions Menace (Nissan TechNews, May 2018) — Nissan North America (hosted by AutomotiveTechInfo) ,
  4. OBD Test Reference (rev 8.6) — California Bureau of Automotive Repair ,
  5. What do you mean my car is not ready? — New York State DMV
  6. Recall acknowledgement 17V-088: BMW i3 REx fuel tank vent line may chafe — BMW of North America / NHTSA
  7. Part 573 Safety Recall Report 15V-621 (Mazda 8615J): liquid fuel can enter the EVAP canister — Mazda North American Operations / NHTSA
  8. Cal. Code Regs. Tit. 13, § 1968.2 — Malfunction and Diagnostic System Requirements (OBD II) — California Air Resources Board (via Cornell LII)
  9. GM 23-NA-073: P0442, P0446, P0455 or P0449 from dust intrusion into the canister and vent solenoid — General Motors / NHTSA ,
  10. Driveability Corner, August 2014 (Mark Warren) — MOTOR Magazine ,
  11. VW 20 17 02: EVAP purge valve (N80) diagnosis — Volkswagen of America / NHTSA ,
Last reviewed
Written by
Saurabh K.
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