- Vehicles
- Cars
P0455
P0455 (generic OBD-II): large leak in the EVAP vapour system
Risk level
Medium
Proceed carefully and stop if the check is unclear.
Urgency
Medium
Quick answer
The EVAP test could not pull vacuum on the tank and its lines: there is a large leak or something open. Check the fuel cap. If you smell petrol, do not start the car or smoke nearby, and call for assistance.
Safety first
Stop and check this first
- If you smell petrol in or around the car, do not smoke, do not light anything and do not drive; call roadside assistance.
Safe checks you can perform
- Fuel cap and filler neck
- Petrol smell and stains
- Companion EVAP codes
Leave these tasks to a qualified professional
- Do not attempt this professional task: Smoke test and purge hose inspection
- Do not attempt this professional task: Bulletin by VIN and other faults first
- Do not attempt this professional task: EVAP monitor completed after the repair
What a technician must be able to justify
Technician visit
These are the steps they must carry out and show you. Tick them as they work: if steps are skipped, do not accept a part swap.
These are not instructions for opening or handling the equipment yourself. They are the checks that should support a technical conclusion.
Smoke test and purge hose inspection
What they doThe technician fills the EVAP system with smoke and pays particular attention to the purge valve hoses and canister joints.
They must show youa photo or video of the leak point found.
In writingwhich hose or part is replaced, its number and the reason.
Bulletin by VIN and other faults first
What they doThe workshop reads all codes with its equipment, fixes non-EVAP faults first and searches bulletins for your VIN.
They must show youthe code list read and the bulletin search result.
In writingthe bulletin applied or that none exists, and the other faults repaired.
EVAP monitor completed after the repair
What they doAfter the repair, the technician lets the EVAP monitor run again and confirms P0455 does not return.
They must show youthe EVAP monitor as complete.
In writingthe date and mileage at which it completed with no code.
Before accepting a part or repair
Nothing has been shown yet. Do not accept a part swap based on the code alone.
Follow these steps
Note: Follow the documented order. An error code identifies the affected system, but it does not prove by itself which part has failed.
Fuel cap and filler neck
- Who:
- you, with the engine off.
- How:
- check the cap is fitted and tight and the filler neck is not dented and its seal is not damaged.
- Result that matters:
- whether the cap was missing, loose or its seal broken.
- If it was loose or faulty:
- close it properly and drive for a few days; if the code does not return, that was the cause.
- If it was fine:
- this rules out the cap; the leak is in lines, canister or valves.
- Evidence to keep:
- a photo of the cap and the filler neck.
No flames or cigarettes near the filler neck.
Evidence: Nissan USA malfunction indicator light guide · Ford 2020-2023 gasoline OBD system operation
Petrol smell and stains
- Who:
- you, outdoors with the engine off.
- How:
- look for a fuel smell and wet stains under the tank or the engine bay.
- Result that matters:
- whether there is a smell or a drip.
- If there is a strong smell or a drip:
- do not start the car or smoke; it may be a liquid leak; call roadside assistance.
- If no smell and no drip:
- this fits a vapour leak; book a visit.
- Evidence to keep:
- a photo of any stain and where you noticed the smell.
Do not get under the car or look for the leak with a flame.
Evidence: Ford 2020-2023 gasoline OBD system operation
Companion EVAP codes
- Who:
- you, with a generic OBD-II reader.
- How:
- read codes and note whether P0455 comes with P0456, P0442 or electrical codes for the vent or purge valve.
- Result that matters:
- whether there is an electrical valve fault as well as the leak.
- If there is a valve circuit code:
- the workshop checks that circuit before hunting for the leak.
- If only leak codes:
- this points to a physical opening; smoke test at the workshop.
- Evidence to keep:
- a photo of the codes and the freeze frame.
Use the reader with the car stopped and do not clear the codes.
Evidence: FCA TSB 25-002-15 Rev A Jeep Grand Cherokee P0455 · Ford 2020-2023 gasoline OBD system operation
Still not solved
If the error persists, stop here. See what the technician must do and show you.
Where this code applies
A code is meaningful only inside the right product and version context.
Primary scope
- System
- Vehicles
- Brand
- OBD-II genérico
- Product type
- Cars
Known code variants
- Jeep P0455
- P0455
- P0455 code Jeep
- P0455 EVAP large leak
- P0455 fuga grande EVAP
- P0455 Jeep
- P0455 OBD2
What it means
P0455 is the generic code for a large leak in the EVAP system. In Ford's OBD summary the same engine-running vacuum test sets P0455 when the system does not reach the expected vacuum in the first phase, and P0457 when that happens right after refuelling. A system that cannot hold vacuum points to something open: the cap, a disconnected or split line, or a valve. FCA published a split purge hose case with P0455. The code does not locate the part.
Warnings and stop conditions
- Higheditorial warning
If you smell petrol in or around the car, do not smoke, do not light anything and do not drive; call roadside assistance.
Evidence: Ford 2020-2023 gasoline OBD system operation
Symptoms and causes
Probable causes · in order
- Missing or loose fuel capPossible
A loose cap leaves the system open. If the code set after refuelling, Ford separates that case as P0457; with P0455 it is still worth checking first.
Evidence: Nissan USA malfunction indicator light guide · Ford 2020-2023 gasoline OBD system operation
- Split or loose purge hosePossible
FCA attributed P0455 and P0456 on 2015 Jeep Grand Cherokee and Dodge Durango to a split purge valve vapour hose. It is located with a smoke test.
Evidence: FCA TSB 25-002-15 Rev A Jeep Grand Cherokee P0455
- Vent valve or canisterPossible
If the canister vent valve does not close, the system cannot pull vacuum. Ford lists it among the components that must be working.
Evidence: Ford 2020-2023 gasoline OBD system operation
Virtual technician
Does P0455 still appear after these checks?
Answer a few questions to narrow down the likely cause and the safest next action. Guidance only - it never replaces a professional.
Sources and technical references
- 1
Nissan USA malfunction indicator light guide
Nissan USA · official_doc
- 2
FCA TSB 25-002-15 Rev A Jeep Grand Cherokee P0455
FCA US LLC · 2015 · service_bulletin
- 3
Ford 2020-2023 gasoline OBD system operation
Ford Motor Company · 2023 · manual
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