Evaporative Emission System Vent Valve Control Circuit Low
P0498 indicates a fault related to evaporative emission system vent valve control circuit low. Learn the likely causes and a practical diagnostic order before replacing parts.
What you may notice
Symptoms
- 01Warning light may illuminate
- 02System function may be impaired
- 03Symptoms depend on the vehicle and fault conditions
Where to look first
Common causes
- 01A leaking cap or hose, stuck valve, pressure sensor fault, or damaged wiring can affect EVAP tests.
- 02Connector, wiring, ground, or supply-voltage fault
- 03Vehicle-specific mechanical or control problem
A sensible sequence
Best diagnostic order
- 01Record codes and freeze-frame data
- 02Inspect the fuel cap and EVAP hoses, then test purge and vent commands and tank pressure with the vehicle-specific procedure.
- 03Compare results with vehicle-specific service information
- 04Verify the repair and monitor readiness
Step by step
What to check and repair
- 01Inspect the fuel cap and EVAP hoses, then test purge and vent commands and tank pressure with the vehicle-specific procedure.
- 02Repair the confirmed cause and retest under the original fault conditions
Read the signals
Live-data clues
EVAP pressure and valve commands
- Typical behavior
- Plausible for the current operating condition and vehicle specification
- Possible clue
- An implausible value or dropout helps localize the fault
| Parameter | Typical behavior | What it can suggest |
|---|---|---|
| EVAP pressure and valve commands | Plausible for the current operating condition and vehicle specification | An implausible value or dropout helps localize the fault |
What P0498 means
P0498 is an OBD2 diagnostic trouble code for evaporative emission system vent valve control circuit low. The code identifies a detected condition, not a confirmed failed part.
Diagnostic direction
Inspect the fuel cap and EVAP hoses, then test purge and vent commands and tank pressure with the vehicle-specific procedure.
Before clearing the code
Save stored and pending codes and freeze-frame data. Confirm the exact vehicle procedure and specifications, repair the verified cause, and repeat the applicable test or drive cycle.