P0457: EVAP leak detected from the fuel cap being loose or off
Loose or missing fuel cap
Severity: Monitor
EVAP faults let fuel vapour escape but rarely change how the car drives, and the main risk is a failed emissions test, so it is safe to drive while you arrange a fix.
It gets more serious if:
- Inspect soon: You keep smelling raw fuel around the car, not just right after filling up
- Stop: You see liquid fuel dripping or pooling under the car, or near the filler, tank or canister
P0457 in short
P0457 means the computer found a leak in the fuel vapour (EVAP) system that it blames on the fuel cap being loose or off. Tighten the cap until it clicks, check its seal for dirt or damage, and the light should go out after a few drives. It is safe to drive.
The EVAP system keeps fuel vapour from the tank sealed in and burns it in the engine later. On cars that set P0457, the computer checks for a leak soon after refuelling and blames a large leak found then on the cap.
Ford says the cap on some of its trucks needs several turns and must click at least once, and that dirt on the seal can also stop it sealing. Chrysler had a bulletin for the same code and its loose fuel cap message.
Once the cap seals, the light goes out by itself after the system re-checks and passes on later drives. If the code keeps coming back with a good cap, there is a leak elsewhere that needs a proper leak test.
Most likely causes
These are general causes for this code across vehicles. None is specific to one make or model.
Cause 1: Fuel cap left loose, not clicked, or missing
Common general cause- Why it ranks here
- This is what the code names, and EPA, Toyota and Ford all point to a cap that was not tightened.
- What would change this
- Rises if the code set right after refuelling. Falls if the cap was tight and clicked.
Cause 2: Dirt or debris on the cap sealing surface
Possible — needs testing- Why it ranks here
- Ford names debris on the sealing surface as a cause on some trucks and vans, and cleaning it is a free check.
- What would change this
- Rises if you find grit on the seal or the filler opening.
Cause 3: Damaged or non-factory fuel cap
Common general cause- Why it ranks here
- A cut or rolled seal, or a cap that is not a factory or equivalent part, may not seal even when tight. Toyota says to use only a genuine cap.
- What would change this
- Rises if the seal is cracked, cut or rolled, or the cap is aftermarket.
Cause 4: Filler neck or cap seat not sealing
Possible — needs testing- Why it ranks here
- A good cap still leaks if the neck it seals against is damaged or covered, as in a GM bulletin where a rubber insulator rolled over the neck.
- What would change this
- Rises if the rubber around the neck is rolled or the neck lip is dented.
Cause 5: A leak elsewhere in the EVAP system
Possible — needs testing- Why it ranks here
- Ford sends technicians to the full leak test if the code returns after the cap is cleaned and reseated, so a leak elsewhere is possible but less likely.
- What would change this
- Rises if the code returns with a good, clean, tight cap, or a smoke test finds a leak.
What to test first
Start at step 1. Each result tells you what it means and where to go next.
Step 1: Remove the fuel cap and refit it, turning it until it clicks at least once.
IfThe cap was missing, loose or had not clicked
It meansThat is very likely the cause. Drive normally and let the system re-check.
IfThe cap was already tight and clicked
It meansLook at the cap seal.
Step 2: With the engine off, look at the cap seal and the filler opening in good light.
Warning:Fuel vapour is flammable. Work outdoors with the engine off and cool, and keep sparks, cigarettes and open flames away.
IfDirt or grit on the seal or the filler opening
It meansWipe both clean and refit the cap until it clicks.
IfThe seal is cut, cracked or rolled, or the cap is not a factory or equivalent part
It meansReplace the cap.
IfCap and seal look good
It meansCheck the filler neck.
Step 3: Look at the filler neck lip and the rubber around it.
Warning:Fuel vapour is flammable. Work outdoors with the engine off and cool, and keep sparks, cigarettes and open flames away.
IfThe rubber is rolled over the neck or the lip is damaged
It meansThe cap cannot seal against it.
IfEverything looks right and the code keeps coming back
It meansA shop leak test is needed.
Step 4: Have a shop run the maker's EVAP leak test or a smoke test.
Warning:Shop test on the fuel vapour system. Fuel vapour is flammable.
IfSmoke escapes at a hose, fitting or other part
It meansRepair that leak.
IfSmoke escapes only at the filler
It meansThe cap or neck is still not sealing.
Symptoms
- Check engine light on, usually with no change in how the car drives
- "Check fuel cap" or loose fuel cap message on cars that have one
- Fails an emissions or smog test because of the light or an incomplete EVAP monitor
- Persistent raw fuel smell around the car Gets more serious: stop and have it checked.
- Liquid fuel dripping under the car Gets more serious: stop and have it checked.
Compare with: Check engine light came on after getting gas
How to fix
Step 1: Check the fuel cap is a factory or OEM-equivalent part, then tighten it until it clicks.
Warning:Engine off, no smoking or flames near the filler.
Step 2: Look at the cap seal for cuts, cracks or a rolled o-ring and replace the cap if it is damaged.
Step 3: Stop filling once the pump clicks off the first time. Topping off can flood the canister.
Step 4: On caps that need several turns, keep turning until you hear at least one click.
Step 5: After a repair, drive normally for several days so the monitor can re-run. Clearing codes or disconnecting the battery resets readiness, so do it shortly before an inspection only if you then complete a drive cycle.
Parts and cost context
- Fuel (gas) cap:Clean and reseat the cap before buying one. If you do replace it, use a factory or OEM-equivalent cap.
Labor varies by vehicle and shop; get a quote before you approve a repair.
Compare used part prices on PartPriceGuideOn your vehicle
FordYour car
2021–2023 · F-250 Super Duty · 6.2L, 6.8L, 7.3L
Supported by vehicle dataFord SSM 51719 links P0457 and/or P0455 to a cap that was not turned until it clicked, or dirt on its seal. It covers the 2021–2023 F-Super Duty range and E-Series with these gasoline engines. The bulletin is on NHTSA, but whether it is still current is not verified, so it is labelled vehicle data rather than confirmed.
Where it is:Fuel filler cap
2021–2023 · E-350 · 6.2L, 6.8L, 7.3L
Supported by vehicle dataThe same Ford SSM 51719 covers the E-Series vans: turn the cap until it clicks and keep the seal clean before chasing other leaks. The bulletin is on NHTSA, but whether it is still current is not verified, so it is labelled vehicle data rather than confirmed.
Where it is:Fuel filler cap
SSM 51719Status unverified
P0457 and/or P0455 from fuel cap installation or debris on the cap seal
2021–2023f-250-super-duty, f-350-super-duty, f-450-sd, f-550-sd, f-600-sd, f-650-sd, f-750-sd, e-150, e-250, e-350, e-450 · 6.2L, 6.8L, 7.3L · issued · NHTSA 10237971
The cap on these trucks and vans takes several turns and must be turned until it clicks at least once. Dirt on the sealing surface can also stop it sealing. Clean and reseat the cap first, and run the workshop manual leak test only if the codes come back. Only the NHTSA flat-file summary was reviewed, not the bulletin itself.
We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.
DodgeYour car
2005–2006 · Durango
Supported by vehicle dataChrysler bulletin 1400106 covers the loose fuel cap message or check engine light with P0457 on several 2005–2006 Dodge models, including the Charger, Dakota, Grand Caravan, Magnum and Ram 1500. Only its title was reviewed. The bulletin is on NHTSA, but whether it is still current is not verified, so it is labelled vehicle data rather than confirmed.
1400106Status unverified
Loose fuel cap message or check engine light for P0457
2005–2006charger, dakota, durango, grand-caravan, magnum, ram-1500 · issued · NHTSA 10019243
Covers the loose fuel cap message or check engine light with P0457 on 2005–2006 Dodge and Jeep models. The NHTSA flat file gives only the title, so the repair it prescribes is not described here.
We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.
JeepYour car
2005–2006 · Grand Cherokee
Supported by vehicle dataThe same Chrysler bulletin 1400106 lists Jeep models, including the Grand Cherokee, Commander, Liberty and Wrangler. Only its title was reviewed. The bulletin is on NHTSA, but whether it is still current is not verified, so it is labelled vehicle data rather than confirmed.
1400106Status unverified
Loose fuel cap message or check engine light for P0457
2005–2006charger, dakota, durango, grand-caravan, magnum, ram-1500 · issued · NHTSA 10019243
Covers the loose fuel cap message or check engine light with P0457 on 2005–2006 Dodge and Jeep models. The NHTSA flat file gives only the title, so the repair it prescribes is not described here.
We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.
Related codes
P0457 questions
Can a loose gas cap really cause this code?
Yes. OBD systems can detect the vapour leak from a cap that is not tightened. After you tighten or replace it, the light should go out by itself once the system re-checks and passes on later drives, which can take several trips.
I tightened the cap. Why is the light still on?
The light stays on until the system re-checks and passes, which can take several drives. If the code keeps coming back with a clean, tight cap, have the EVAP system leak tested.
Is it safe to keep driving?
Usually yes, as long as there is no strong fuel smell and no fuel dripping. Most makers advise getting it fixed when it is convenient. A strong fuel smell means get it checked soon, and dripping fuel means stop and do not drive.
Will this code fail an emissions inspection?
In states that test OBD-II, a check engine light that stays on with the engine running fails the test. Clearing the code does not help straight away, because the EVAP monitor then reads not ready until the car completes a drive cycle.
Sources and review
- Frequently Asked Questions on On-Board Diagnostics (EPA 420-F-97-003)
- On-Board Diagnostic II (OBD II) Systems Fact Sheet
- EVAP: The Phantom Emissions Menace (Nissan TechNews, May 2018)
- OBD Test Reference (rev 8.6)
- What do you mean my car is not ready?
- Recall acknowledgement 17V-088: BMW i3 REx fuel tank vent line may chafe
- Part 573 Safety Recall Report 15V-621 (Mazda 8615J): liquid fuel can enter the EVAP canister
- Toyota Camry Owner's Manual (OM06291U, 2.5L A25A-FKS / 3.5L 2GR-FKS)
- Ford SSM 51719: P0457 and/or P0455 from fuel cap installation or debris on the cap seal
- Chrysler 1400106: loose fuel cap message or MIL for P0457
- GM PIC6030: P0442 from fuel filler pocket insulator rolled over the filler neck
- Last reviewed
- Written by
- Saurabh K.
- Editorial review
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- Technician review
- Technician review pending
This page explains what a code usually means; it is not a substitute for a professional inspection. How we source and review · Report an error