EVAP gross leak on Honda — fuel cap and well-known charcoal canister vent valve on Civic/Jazz.
Honda P0455 — EVAP gross leak on Honda — fuel cap and well-known charcoal canister vent valve on Civic/Jazz. Typical UK independent garage cost: £25–£320.
What actually causes P0455 on a Honda
Honda P0455 — fuel cap first, vent valve second. Honda issued a service campaign on certain vent valves; check VIN.
Honda engines that log P0455
- Civic 1.4/1.8/2.0
- Jazz 1.2/1.4
- CR-V 2.0/2.4
How we diagnose P0455 on a Honda
- Fuel cap test
- VIN check for campaign
- Vent valve test
- Smoke-test EVAP
The common misdiagnosis to avoid
Honda dealers replace canister assemblies under campaign — out of scope, the vent valve alone works.
Honda P0455 repair cost in the UK
Expect £25–£320 including parts and labour at an independent garage. Main-dealer quotes on Honda 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.
Service campaign / TSB note
Honda vent valve service campaign covers selected Civic/CR-V production.
Bob's workshop tip
Civic P0455 — VIN check is free, do it first.
Codes usually seen alongside P0455 on Honda
- P0441
- P0456
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.
Reading P0455 on a Honda properly
A generic reader will show P0455 and nothing else. What matters is the freeze-frame data stored with it — engine speed, load, coolant temperature and fuel trims at the moment the fault was logged — plus whether any other module on the Honda has logged something at the same time. Codes rarely arrive alone, and the order they were stored in usually points at which one is the cause and which are the consequences.
Clearing P0455 without fixing it
Erasing the code resets the Honda's readiness monitors as well as the light. The fault returns on the next drive cycle if the cause is still there, and in the meantime the incomplete monitors can stop the car passing an emissions check. After a genuine repair, the car is driven until the relevant monitor completes before it is handed back.
Bob's Mechanical Repairs is an independent garage in Birnam, Dunkeld, Perthshire, with 32 years of Bob's experience on the tools. If P0455 is showing on your Honda, bring any scan results with you — we will read the live data ourselves, confirm which cause it actually is, and price the repair before any work starts.