P0455

Code

Generic P — Powertrain

EVAP System Leak Detected - Large Leak

Brand: Generic

Type: P — Powertrain

Views: UK: 63 EN: 68 RU: 109

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Page language: EN

Causes

Loose, not fully tightened, or missing fuel filler cap
Damaged, cracked or deteriorated EVAP hoses/lines or loose clamps/quick-connects
Cracked/damaged fuel filler neck or fuel tank
Cracked or saturated charcoal canister
Disconnected or broken EVAP system fittings
Failed vent control valve/vent solenoid stuck open

Symptoms

Malfunction Indicator Lamp (MIL/CEL) illuminated
Strong fuel odor around vehicle or near fuel tank/filler area
Possible trouble starting or rough idle in rare cases (usually little drivability change)
Failed emissions/inspection test
EVAP system monitor shows failed

What to check

Read and record DTC(s) and freeze-frame data with a scan tool
Verify fuel cap is present, threads undamaged and tightened until it clicks; inspect cap seal
Visual inspection of EVAP hoses, fittings, clamps, filler neck, and charcoal canister for cracks or disconnections
Sniff for fuel odor near suspected components and along hose routes
Inspect filler neck and tank for dents, corrosion, or punctures
Perform smoke test or pressure/vacuum decay test to locate large leaks

Signal parameters

Rapid pressure drop / vacuum decay in EVAP test greater than manufacturer threshold
Leak size equivalent typically considered 'large' (manufacturer-specific; commonly ≳0.040 in / ~1 mm)
EVAP monitor failed-to-pass status in readiness data
Purge and vent solenoid command/responses from scan tool (open/close state, commanded vs. actual)
Fuel tank pressure sensor (if equipped) readings during EVAP test (pressure vs. expected)

Diagnostic algorithm

Connect a capable scan tool. Record stored codes, freeze-frame and readiness status. Note if multiple EVAP codes are present.
Perform a basic check: confirm fuel cap is installed and tightened until it clicks. Inspect cap seal; replace cap if damaged. Clear codes and re-run drive/monitor cycle to see if P0455 returns.
Visually inspect filler neck, cap, hoses, clamps, canister and connections. Repair or reconnect any obvious damage or disconnections.
If no visible fault, perform a smoke test (or equivalent EVAP pressure/vacuum decay test) to locate large leaks. Inspect the whole EVAP plumbing including undercarriage, filler neck and tank seams while pressurized.
Isolate sections as needed: block vent line or disconnect purge valve and re-test to identify whether leak is on tank/canister side or downstream.
Test vent control valve/vent solenoid: verify operation, commanded closure and continuity. Replace if stuck open or faulty.
Test purge valve operation (electrical and mechanical) and inspect purge hoses for leaks or disconnection.
If smoke or pressure testing reveals a cracked filler neck, tank or canister, replace the damaged component(s). Repair/replace any leaking hoses or fittings and secure clamps.
After repairs clear codes, perform required drive cycle or run EVAP monitor with scan tool to confirm repair and that code does not return.
If code persists after repairs and no leak is found, verify sensor inputs (fuel tank pressure sensor) and ECU/PCM software updates or manufacturer-specific diagnostic notes.