P0457: Evaporative emission system leak detected, fuel cap loose or off
What the code tells you on its own
- System
- Powertrain
- Functional group
- EVAP and fuel tank
- Subsystem
- Auxiliary emission controls
Engine, fuel, air, ignition, emissions and transmission. The overwhelming majority of what workshops bring to the AI.
What we see when P0457 turns up
Measured across the diagnostics run through Wrenchlane, not taken from a reference table. Figures as of 2026-10-06.
- Diagnostics
- 1
- Separate workshops
- 1
- Arrived code only
- 0%
- Most common marque
- Volkswagen
July 2026
Seen at a single shop so far
No symptom description entered at all
Where we have seen it most
These are counts from our own work, not a claim about how common the fault is across all vehicles. They describe what independent workshops brought to us, which is a narrower and more specific thing.
Run P0457 against the car in front of you
Enter the code and the symptoms and get ranked probable causes for that specific vehicle, with the checks in the order worth doing them. Free account, no card.
Start freeOther evap and fuel tank codes
- P0441 Evaporative emission system incorrect purge flow
- P0443 Evaporative emission system purge control valve circuit
- P0456 Evaporative emission system leak detected, very small leak
- P2066 Fuel level sensor B circuit range/performance
- P049B Not individually documented
- P0451 Evaporative emission system pressure sensor range/performance
- P0444 Evaporative emission system purge control valve circuit open
- P049C Not individually documented
FAQ
Frequently asked questions
How do I run a diagnosis?
Select the vehicle on Start, click the Diagnostic card and choose New diagnostic. Fill in the description, the error codes and the mileage, then click Analyze.
Learn more: Diagnostic (vehicle-first start), Diagnostic form: description, error codes and mileage
Do I have to type the codes from my scan tool?
No. Click the camera button next to Error codes and take or choose a photo (JPEG or PNG) of the scan tool's screen; WrenchLane reads the codes and their descriptions into the form. You can also speak them with the microphone.
Learn more: OBD reader photo scan (fault codes from a photo), Voice input for the problem description
Are the public fault code pages built from my diagnostics?
They are built from anonymised, aggregated diagnostics run in WrenchLane; no workshop, customer or vehicle can be identified. Each fault code page shows how often the code was seen across those diagnostics and in how many separate workshops.
Learn more: Fault code pages on wrenchlane.com (fault-code cluster)