EVAP system gross leak on BMW — fuel cap, purge valve and the leak-detection pump (LDP) on US-spec cars.
BMW P0455 — EVAP system gross leak on BMW — fuel cap, purge valve and the leak-detection pump (LDP) on US-spec cars. Typical UK independent garage cost: £40–£320.
What actually causes P0455 on a BMW
BMW EVAP systems are sensitive to fuel cap seal condition — that's check one. The canister purge valve (sits on the intake manifold) also fails commonly with age. US-spec BMWs use a leak-detection pump that can fail and trigger P0455, but UK cars use the engine-off natural vacuum test which is less prone to false flags.
BMW engines that log P0455
- All BMW petrol models
- N20, N52, N54, N55, B48 engines particularly
How we diagnose P0455 on a BMW
- Check fuel cap seal condition and tightness
- ISTA: trigger purge valve activation test
- Smoke-test EVAP system from the service port
- Inspect intake manifold purge line for cracks at the valve
- Clear code, drive 2–3 cycles, recheck
The common misdiagnosis to avoid
Don't condemn an expensive EVAP component before testing the fuel cap and purge valve with a scan tool — these solve the majority of BMW P0455 codes.
BMW P0455 repair cost in the UK
Expect £40–£320 including parts and labour at an independent garage. Main-dealer quotes on BMW 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
BMW purge valves are integrated into a plastic manifold on later N20/B48 — replacement is straightforward but the valve isn't sold separately on some models, you buy the manifold-mounted assembly.
Codes usually seen alongside P0455 on BMW
- 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.