P0457 Evap Emission System Leak Detected (fuel Cap Loose/off)

Code: P0457
Applies To: Most makes, generic code
Loose Cap Can Set It: Yes
Typical Fix: $138 to $150 at RepairPal

The computer thinks the gas cap is loose or missing, usually right after a fill up.
Check the gas cap first. A shop confirms it with the carmaker's EVAP test and a smoke machine before replacing parts.
Usually yes for now, but get it fixed soon and check for open recalls.

What The Carmakers Call It

EVAP emission system leak detected (fuel cap loose/off), as printed by Volkswagen Group of America
gross leak, cap off, as printed by Ford Motor Company

Causes Named In Carmaker Bulletins

Ford sets it when the system cannot reach test vacuum after a refueling event. On capless fillers, the car may show a message to check the capless fuel fill valve. (source)

No source ranks these by how often they happen, so they are listed as the bulletins give them.

This is the loose or missing cap code. Ford may also show a Check Fuel Cap light, and turns the MIL on after two or three trips depending on calibration.

Ford says not every vehicle has the P0457 test. Those set only P0455.

What The Fix Costs

The usual part for this code is the gas cap. Published estimates put it at $138 to $150 at RepairPal. The full table with every source and date is on the cost page. A diagnosis first keeps you from paying for a part you did not need, which is why we price what a check engine diagnostic costs before the fix.

Getting The Light To Go Off

After the repair the light goes off once the EVAP test runs and passes on three drive cycles in a row, and the code is erased after 40 warm up cycles, per CARB. The test only runs under set conditions such as a fuel level between about 15 and 85 percent, so it can take days.

P0455Evap Emission Control System Gross Leak Detected P1456Evap Control System Leakage [fuel Tank System]