P0497 EVAP Purge Flow Low on Smart Fortwo 451 / 453
P0497 indicates the EVAP purge valve isn't moving enough vapor. On a Smart, it usually traces back to something simple: the fuel cap, a cracked vacuum hose, a sticky purge solenoid, or a charcoal canister damaged by a pothole hit. Many owners report this being covered under emissions warranty, so check coverage before buying parts.
Typical Symptoms
- Check engine light with P0497
- No noticeable drivability problem
- Appears after long highway runs
- Sometimes paired with other EVAP codes like P0455, P0457, or P0442
What it means
The EVAP system stores fuel vapors in a charcoal canister and bleeds them back into the engine through a purge valve. P0497 fires when the computer commands the purge valve open but doesn't see the expected flow. It's a flow problem, not a leak code, so the focus is on the cap, hoses, valve and canister rather than general leak testing.
Likely causes, cheapest first
- Fuel cap loose, worn seal or wrong cap. Always seat it until you hear three clicks and make sure the seal isn't cracked.
- Cracked or disconnected vacuum line to the purge valve. Inspect the small hose between the intake and purge solenoid for splits or popped fittings.
- Purge valve stuck closed. The solenoid should tick quietly at idle; silence usually means the valve or its wiring has failed.
- Charcoal canister cracked or damaged from road debris. On the 451 it sits low under the driver's floorboard and can be hit by speed bumps or potholes.
- Filler neck cracked or its seal degraded. Rare but worth checking if the other items are fine.
DIY check steps
- Reseat the fuel cap firmly until it clicks three times, clear the code and drive through two warm‑up/cool‑down cycles.
- With the engine cover off and ignition on, listen for a soft clicking from the purge solenoid; silence points at the valve or its connector.
- Inspect the vacuum hose between the intake and purge valve for cracks, hardened rubber or popped-off fittings and replace what you find.
- Check the charcoal canister and its brackets for cracks or impact damage, particularly if you've recently hit a pothole or speed bump.
- If the purge solenoid is silent and the connector is clean, replace the valve – it's a simple two-bolt job.
When to call a shop
If the cap, hose and purge valve all check out, a shop smoke test is the next step. A low‑pressure smoke generator will find pinhole leaks you can't see. Replacing the charcoal canister is awkward due to its location; many owners have a specialist handle it. Also check if your car is still under emissions warranty – dealers have covered this repair for many owners.
Related parts & typical prices
| Part | Typical price | Search |
|---|---|---|
| Fuel cap | $15-30 | Search Google |
| EVAP purge valve / solenoid | $30-90 | Search Google |
| Charcoal / EVAP canister | $80-220 | Search Google |
| EVAP vacuum hose / line | $10-25 | Search Google |
Prices are rough community-reported ranges, not quotes. Aftermarket vs. genuine Mercedes parts swing the spread; call a Smart-experienced shop for an actual quote.
Manual references
- Service manual on Manualslib — external mirror (we don't host this specific document).
- Browse Smart manuals on smartcarmanuals.com — pick your chassis code section on the home page if a specific manual isn't listed above.
Community references
- r/SmartCar: First smart! (P0497 troubleshooting thread)
- Evilution: OBD-II error code reference
- FQ101: OBD code lookup
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