P0457: Evaporative Emission Control System Leak Detected (Fuel Cap Loose/Off)
Quick Answer
Safe to drive (short-term)
P0457 means the ECU detected an evaporative system leak consistent with a loose, missing, or damaged fuel cap. The code is specifically tuned to flag cap-sized leaks before flagging generic small (P0442) or large (P0455) leaks. The first thing to check is always the cap itself.
- Severity
- Low · EVAP System
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Get Skanyx freeWhat does P0457 mean?
P0457 is a evap system-related diagnostic trouble code classified as low severity. When your vehicle's ECU detects this condition, it stores P0457 and illuminates the check engine light.
Where it is on the car
- Fuel filler cap
- Fuel tank pressure sensor
- Charcoal canister
- Vent valve (to fresh air)
- Purge valve
- Intake manifold and engine
What are the symptoms of P0457?
If your vehicle has triggered P0457, you may notice one or more of these symptoms:
- Check engine light illuminated
- Fuel cap warning indicator on some vehicles (Ford, GM, some VAG)
- Faint fuel odour when stationary, especially after refuelling
- Rejection at an emissions test
- No noticeable driveability issues
What causes P0457?
Here are the most common causes of P0457:
Loose fuel cap (not tightened until click)
: high
Worn or cracked fuel cap rubber seal
: high
Missing fuel cap (left at fuel station)
: medium
Damaged fuel filler neck seal or threads
: medium
Capless filler flap not sealing (Ford Easy Fuel and other capless designs)
: low
Is it safe to drive with P0457?
Generally yes, for short-term driving. P0457 is specifically a fuel cap leak code and has no effect on engine performance or safety. Tighten the cap immediately and drive normally. Until the code clears, the lit warning lamp is also the kind of defect an inspector rejects a car for, although how it is graded depends on the country.
How do you diagnose P0457?
Follow these steps to pinpoint the root cause of P0457:
- Remove the fuel cap and inspect the rubber seal for cracks, brittleness, or debris. If the seal compresses unevenly when squeezed, replace the cap
- Re-seat the cap and tighten until it clicks. Clear the code and drive for 3 to 5 cycles to let the EVAP monitor retest
- If the code returns with a known good cap, inspect the fuel filler neck. Look for damage to the threads or to the sealing surface where the cap meets the neck
- On capless filler systems (such as Ford Easy Fuel), inspect the flapper assembly for debris, damaged seals, or a stuck flapper. Clean carefully or replace the assembly if damaged
- If the cap and filler neck are good, perform a smoke test focusing on the upper portion of the EVAP system. A leak at the tank top or fuel pump module gasket can mimic a cap leak
How much does P0457 cost to fix?
Repair costs for P0457 vary depending on the root cause and your vehicle. Here are typical estimates:
| Repair | Parts Cost | Labor Cost | Total Estimate | DIY Difficulty |
|---|---|---|---|---|
| Tighten existing fuel cap (free fix) | €0–€0 | €0–€0 | €0–€0 | Easy |
| Replace fuel cap | €10–€40 | €0–€0 | €10–€40 | Easy |
| Replace fuel filler neck or capless flapper assembly | €80–€300 | €80–€200 | €160–€500 | Professional |
Prices estimated as of March 2026. Costs vary by region, vehicle, and shop.
Full repair guides
P0457 on specific vehicles
P0457 behaves differently depending on your vehicle. Select your car below for model-specific causes and known issues:
P0457 on BMW
BMW 3 Series
P0457 on Volkswagen
Volkswagen Golf
P0457 on Audi
P0457 on Ford
Ford Focus
Related diagnostic codes
These codes are often seen alongside P0457 or indicate related issues:
Common questions about P0457
- How long does P0457 take to clear after I tighten the cap?
- After tightening the cap or replacing it, the ECU needs 3 to 5 complete drive cycles to retest the EVAP system and clear the code. A drive cycle includes a cold start, mixed driving over 15 to 20 minutes, and shutdown. You can also clear it manually with a scan tool to confirm the fix immediately.
- Is P0457 different from a generic EVAP leak code?
- Yes. P0457 is specifically tuned to the leak size associated with a loose or missing fuel cap (typically a medium-size leak). The ECU sets P0457 rather than the generic P0455 (large leak) or P0442 (small leak) when the leak profile matches a cap-sized opening, giving the driver a more specific hint.
- Why does my fuel cap warning light keep coming on?
- If you've already tightened the cap and the light returns, the rubber seal is most likely worn, cracked, or contaminated with fuel residue. Replacement caps cost 10 to 40 EUR and take seconds to install. Always buy a manufacturer-spec or OEM-equivalent cap, not the cheapest universal option.
- Can topping off the fuel tank cause P0457?
- Yes, indirectly. Overfilling the tank past the first click of the fuel nozzle can saturate the charcoal canister with liquid fuel. A saturated canister cannot hold vacuum properly during EVAP self-tests and can set leak codes including P0457. The fix is to stop topping off and let the system self-recover over several drive cycles.
Read our detailed guides
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- How to Fix P0446: EVAP Vent Solenoid Repair CostFixing P0446 costs 70-180 euros total to replace the EVAP vent solenoid. Check the connector for corrosion first, as wiring is the second most common cause.
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Scan your car with Skanyx to diagnose P0457
Your car logged P0457. Skanyx reads it on a standard OBD2 adapter (Bluetooth LE on iPhone), tells you whether it is safe to keep driving, and breaks down the likely repair so you know the number before a shop quotes you. Free on iPhone and Android, and you do not need to be a mechanic to read it.
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