P0496 fault code: Evaporative Emission System High Purge Flow

P0496 means “Evaporative Emission System High Purge Flow” — an auxiliary emission controls fault in the powertrain.

Can I DIY?

Professional-only boundary. You may confirm P0496 and watch idle in open air; purge-flow diagnosis is garage work.

Do not DIYReviewed page boundary
ToolsSpecialist equipment

This is the conservative boundary from the reviewed code record. This page has no frozen site-wide safety grade, so it does not publish a repair route.

What to tell the garage about P0496

Stop driving now. The engine computer thinks too much fuel vapour is being purged from the tank vapour store into the intake (high purge flow). That is a vapour-flow fault, not a leak-size measurement.

Take these reviewed, code-specific details with you. They help the garage confirm the fault without turning this page into a repair procedure.

  • Evaporative Emission System High Purge Flow: Registration number
  • Evaporative Emission System High Purge Flow: Exact code P0496 and any companion codes
  • Evaporative Emission System High Purge Flow: Whether the engine management light is steady or flashing
  • Evaporative Emission System High Purge Flow: Whether idle hunted, surged, or stalled, and any petrol-vapour smell
P04xxAuxiliary emission controls
MOT fail riskif the warning light stays on

What does P0496 mean?

P0496 is a generic (SAE standard) powertrain code reported by your car’s engine control unit. It sits in the P04xx block, which covers auxiliary emission controls. The stored description is “Evaporative Emission System High Purge Flow”. The code itself tells you which circuit or system tripped the fault — not always the exact part that failed.

Will P0496 fail an MOT?

If the malfunction indicator lamp is illuminated when P0496 is stored, DVSA treats that as a Major defect (test fail) until the fault is repaired and the lamp remains off. A high-purge evaporative fault still fails on the lamp, even if the tester never names the purge path.

Before booking your test, check what usually fails on your car: see our MOT pass rates by make and model, built from 33.1 million DVSA tests.

Related guides

Car diagnostic test cost: compare the scopeUK booking marketplaces currently publish diagnostic averages of about £52–£65. Engine management light on: steady or flashing?A steady engine management light means the computer has stored a fault. Drive with caution and get the code read. A flashing light is different — stop when it is safe.
P0400Exhaust Gas Recirculation Flow P0401Exhaust Gas Recirculation Flow Insufficient Detected P0402Exhaust Gas Recirculation Flow Excessive Detected P0403Exhaust Gas Recirculation Control Circuit P0404Exhaust Gas Recirculation Control Circuit Range/Performance P0405Exhaust Gas Recirculation Sensor 'A' Circuit Low P0406Exhaust Gas Recirculation Sensor 'A' Circuit High P0407Exhaust Gas Recirculation Sensor 'B' Circuit Low

P0496 — quick answers

Is it safe to drive with P0496?

Stop driving now. We have no verified driving guidance for P0496. Treat as do not drive until checked. Stop at once if idle collapses, the engine stalls in traffic, or petrol vapour is strong.

Will P0496 fail my MOT?

If the malfunction indicator lamp is illuminated when P0496 is stored, DVSA treats that as a Major defect (test fail) until the fault is repaired and the lamp remains off. A high-purge evaporative fault still fails on the lamp, even if the tester never names the purge path.

Fault-code identifiers are standard diagnostic facts. Their explanations and diagnostic guidance on this site are original editorial summaries, not reproduced SAE wording. MOT defect rules reflect the DVSA MOT inspection manual (2026). This page is general guidance for UK drivers, not a substitute for a professional diagnosis.