Ford P0455

EVAP system gross leak on Ford — almost always a loose or damaged fuel cap, but on EcoBoost the purge valve also fails commonly.

Ford P0455 — EVAP system gross leak on Ford — almost always a loose or damaged fuel cap, but on EcoBoost the purge valve also fails commonly. Typical UK independent garage cost: £25–£350.

What actually causes P0455 on a Ford

P0455 means the EVAP system detected a leak the size of a missing fuel cap. The cap itself or its seal is the cheapest culprit. On EcoBoost engines specifically, the canister purge valve sticks open or fails internally — second most common cause. Cracked EVAP hoses near the canister (under the rear of the car) round out the top three.

Ford engines that log P0455

• All Ford petrol models 2010+
• 1.0/1.5/1.6/2.0 EcoBoost particularly
• Fiesta, Focus, Kuga, Mondeo, Puma

How we diagnose P0455 on a Ford

1. Check fuel cap seal and tightness — replace if rubber seal is hard or cracked
2. Smoke-test the EVAP system via the service port
3. On EcoBoost, test canister purge valve electrically and check for stuck-open behaviour
4. Inspect EVAP lines from tank to engine bay for cracks or rodent damage
5. Clear code, drive 2–3 drive cycles, recheck

The common misdiagnosis to avoid

Don't waste workshop time tracing EVAP leaks before checking the fuel cap and tightening it three clicks — solves P0455 in roughly half of all cases.

Ford P0455 repair cost in the UK

Expect £25–£350 including parts and labour at an independent garage. Main-dealer quotes on Ford are usually higher for the same job, and the spread exists because the cheap cause and the expensive cause throw the same code — pay for the diagnosis before you pay for parts.

Bob's workshop tip

If a customer's just filled up and the EML comes on within 50 miles, P0455 from a poorly seated fuel cap is the prime suspect — tighten cap, drive a few cycles, code clears.

Codes usually seen alongside P0455 on Ford

• P0440
• P0442
• P0496

Symptoms drivers report with P0455

• Engine warning light appears within a mile of filling up — sometimes the cap wasn't clicked shut
• Strong smell of petrol vapour around the car after parking on a hot day
• MPG barely affected — you'll only notice on the fuel receipts over a month
• MOT emissions test passes but the MIL means an MOT visual fail on any car registered 2018+
• Paired codes: P0440 (generic EVAP), P0441 (purge flow), P0446 (vent circuit), P0455 keeps returning

Repairs that clear P0455

• Refit fuel cap
• Inspect hoses

For the generic, all-makes explanation of this code — meaning, every known cause and UK cost bands — see our P0455 guide.