P0498: EVAP Vent Valve Control Circuit Low (Meaning, Causes, Fixes)
What P0498 means
The evaporative emission (EVAP) system captures fuel vapor from the gas tank, stores it in a charcoal canister and later draws it into the engine to be burned instead of letting it escape. The vent valve (often called the vent solenoid) opens and closes the canister's connection to outside air. RepairPal explains that it lets fresh air into the EVAP system so it isn't under constant vacuum, and says the engine computer (PCM) sets P0498 when it detects that the system is venting when it should not. OBD-Codes.com describes it as the PCM detecting a fault with the circuit that controls the vent valve. The two sources frame it differently: OBD-Codes.com treats it as an electrical fault in the vent valve's control circuit, which matches the code's official name ("control circuit low"), while RepairPal's explanation describes the system venting at the wrong time. OBD-Codes.com also describes the vent's job a little differently, as letting tank vapors flow on to the intake or charcoal canister. It is a generic OBD-II code, but the exact test conditions vary by make. OBD-Codes.com says it seems to be common on Dodge, Chrysler and Jeep vehicles, where the vent valve was usually bad, and on GM pickups, where GM released an updated valve assembly. Searches also show it often on Honda (Accord, Civic, Odyssey) and Chevrolet and GMC models. P0499 is the matching "circuit high" code.
Severity: can I keep driving?
Drive with caution, fix soon
RepairPal rates P0498 Moderate: it isn't likely to affect safety or how the car drives right away, but you should get it diagnosed within a reasonable time. OBD-Codes.com says you will likely notice nothing other than the check engine light. An EVAP fault can still make the car fail an emissions inspection, and leaving it can hide other problems behind the check engine light.
Common symptoms
- Check engine light on (both sources)
- Usually no other noticeable symptoms (OBD-Codes.com)
- Possible failed emissions inspection while the code is set
Likely causes
Roughly most to least common, based on the sources below. Your vehicle may differ.
- Faulty EVAP vent valve or vent solenoid (both sources); OBD-Codes.com says this was the usual cause on Dodge, Chrysler and Jeep vehicles
- Wiring or circuit problem, such as a chafed harness or a short to ground, power or between the two wires (both sources)
- Blown fuse feeding the vent solenoid (OBD-Codes.com)
- Vent valve sticking from fuel residue (OBD-Codes.com)
- Engine computer (PCM/ECM) fault, which is less common (both sources)
Diagnostic steps you can do
Work on a cool engine, parked on level ground with the parking brake set. Never work under a car supported only by a jack.
- Read all stored codes. If other EVAP codes are set too, note them, since they can share a cause.
- Check for technical service bulletins for your vehicle. OBD-Codes.com says GM released an updated vent valve assembly for some pickups.
- Check the fuses; one may power the vent solenoid (OBD-Codes.com).
- Find the vent valve (usually near the charcoal canister, often by the fuel tank) and inspect it and its connector for cracks, damage or corrosion.
- Inspect the wiring harness for rubbed-through or chafed spots, and check both wires for shorts to each other, to ground or to power (OBD-Codes.com).
- With a digital multimeter, check the valve's resistance against the manufacturer's spec or a new valve, and check continuity of the wires back to the PCM (OBD-Codes.com).
- If you have a scan tool that can command the valve, actuate it while checking power and ground at the connector; OBD-Codes.com notes a test light wired across both terminals will light if power and ground are OK.
Typical fixes
- Replace the EVAP vent valve or solenoid (both sources), or the updated assembly where the manufacturer has released one
- Repair damaged wiring or connectors in the vent valve circuit (both sources)
- Replace a blown fuse and find what caused it (OBD-Codes.com)
- Clean a sticking valve and retest, if the pintle is accessible (OBD-Codes.com)
- Repair or reprogram the PCM only after the valve and wiring check out (both sources list it as a possible cause)
Repair costs vary widely by vehicle, region, parts brand and shop, so we don't quote prices. Get a written estimate after diagnosis.
🛠 When to call a pro
- The vent valve is mounted near the fuel tank and hard to reach safely without a lift
- You don't have a scan tool that can command the vent valve for testing
- The wiring checks out and the valve is good, so the engine computer may be at fault
- You need the car to pass an emissions inspection soon
Where to buy
Plain search links. Always match parts to your exact year, make, model and engine.
FAQs
Is P0498 serious?
RepairPal rates it Moderate. It usually doesn't change how the car drives, but it should be fixed in a reasonable time, and it can cause an emissions inspection failure.
What's the difference between P0498 and P0499?
Both are vent valve control circuit codes. P0498 is circuit low and P0499 is circuit high, so they point to the same valve and wiring but a different electrical reading.
Can a loose gas cap cause P0498?
Neither source lists the gas cap as a cause. They point to the vent valve, its wiring and, less often, the engine computer. A loose cap more typically sets leak codes such as P0455 or P0457.
How much does it cost to fix P0498?
Neither source gives a repair cost. It depends on whether the valve, wiring or computer is at fault, so get a diagnosis or a written estimate first.
Sources
Last reviewed 2026-10-25. Code definitions and repair steps can vary by manufacturer. Confirm with your vehicle's service information.