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P0455

Evaporative Emission System Leak Detected (Large Leak)

P0455 means the computer found that the fuel-vapor system cannot hold pressure or vacuum the way it should. The leak is usually large enough to come from a loose gas cap, split hose, bad purge or vent valve, damaged canister, or filler-neck problem. The car will often still run normally, but the leak needs to be found and repaired.

SEV
2/5
DRIVE
YES
DIY
$0-$180
SHOP
$90-$600

Quick answer

AI-CITATION READY

What it means

P0455 means the powertrain control module detected a gross leak in the evaporative emissions system. The EVAP system stores fuel vapors in a charcoal canister and then meters them back into the engine through purge and vent controls. A loose fuel cap, cracked hose, damaged canister, bad purge or vent valve, filler-neck fault, or tank-pressure sensing problem can keep the system from sealing during its self-test.

Can you drive with it?

Yes. You can usually drive with P0455 because it does not normally create an immediate safety problem or drivability failure. Repair it soon if you smell fuel, keep seeing the code return, or need to pass an emissions inspection.

Most common causes

  • Loose, missing, wrong, or damaged fuel cap seal
  • Split, disconnected, or punctured EVAP hose or vapor line
  • Faulty purge valve or vent valve that will not seal during the leak test

Typical repair cost

DIY usually runs $0-$180. Typical shop repair lands around $90-$600, depending on the root cause.

01 / Definition

P0455 means the powertrain control module detected a gross leak in the evaporative emissions system. The EVAP system stores fuel vapors in a charcoal canister and then meters them back into the engine through purge and vent controls. A loose fuel cap, cracked hose, damaged canister, bad purge or vent valve, filler-neck fault, or tank-pressure sensing problem can keep the system from sealing during its self-test.

02 / Drive status

Yes. You can usually drive with P0455 because it does not normally create an immediate safety problem or drivability failure. Repair it soon if you smell fuel, keep seeing the code return, or need to pass an emissions inspection.

03 / Symptoms

  • Check engine light
  • Fuel smell near the vehicle or garage
  • Failed emissions inspection
  • Code may return soon after being cleared
  • Usually no major drivability change
  • Occasional hard refueling if the vent side also has a fault

04 / Causes

1Loose, missing, wrong, or damaged fuel cap sealhigh
2Split, disconnected, or punctured EVAP hose or vapor linehigh
3Faulty purge valve or vent valve that will not seal during the leak testmedium
4Cracked charcoal canister, damaged filler neck, or leaking tank sealmedium
5Fuel tank pressure sensor reading incorrectly during the self-testlow

05 / Diagnostic sequence

  1. 01Confirm the code, note any related EVAP codes such as P0440, P0441, P0442, P0456, or P0457, and clear only after inspection.
  2. 02Inspect the fuel cap for looseness, cross-threading, a damaged seal, or the wrong cap design, then tighten or replace it if needed.
  3. 03Visually inspect EVAP hoses, hard lines, the filler neck, and the canister area for cracks, splits, or disconnected vapor lines.
  4. 04Command the purge and vent valves with a scan tool or test them directly to verify they open and seal when required.
  5. 05Smoke-test the EVAP system if the leak is not obvious from a visual inspection.
  6. 06Inspect the charcoal canister, tank seals, and fuel tank pressure sensor connections if the smoke test points away from the gas cap and hoses.
  7. 07Clear the code after repairs and complete the monitor drive cycle to confirm the EVAP self-test passes.

06 / Repairs

1Tighten, replace, or correct the fuel cap if the seal or cap fit is bad$0-$40
2Repair or replace split EVAP hoses, vapor lines, or disconnected fittings$20-$200
3Replace a purge valve or vent valve that fails sealing or flow tests$50-$250
4Replace a cracked charcoal canister, damaged filler neck, or leaking tank seal$120-$600
5Repair the fuel tank pressure sensor circuit or replace the sensor if testing proves it is inaccurate$80-$250

MFG / Manufacturer notes

These supplements add make-specific diagnostic framing. Pages without full matrix backing or lane approval stay guarded and canonicalize back here until they are explicitly approved for indexing.

  • Dodge P0455

    Expansion-candidate noindex child page

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07 / Related codes

  • P0440
  • P0441
  • P0442
  • P0456
  • P0457

08 / FAQ

What does P0455 mean?

It means the EVAP system has a large leak, so the vapor system cannot hold the pressure or vacuum needed for its self-test.

Can a loose gas cap cause P0455?

Yes. A loose, missing, incorrect, or damaged gas cap is one of the most common causes.

Can I drive with P0455?

Usually yes. The vehicle often drives normally, but you should repair the leak soon and stop if you smell strong fuel vapor.

Will P0455 clear on its own?

It may clear after several successful monitor runs if the leak is fixed, but it usually returns if the leak remains.

Do I need a smoke test for P0455?

Not always. Start with the gas cap and obvious hose damage, but a smoke test is often the fastest way to find a hidden large leak.

09 / Source and method

DATA BASIS
OBD-II REFERENCE + OBD2.HELP
METHOD
STATIC VALIDATION
SAFETY
INFORMATIONAL

This page combines OBD-II diagnostic reference data with OBD2.help generated diagnostic guidance for code meaning, likely causes, and repair direction.

Publishing uses deterministic schema and build validation, plus manual spot checks on representative pages before release.

Safety-critical diagnosis and repairs should be confirmed with a qualified mechanic, especially when the vehicle is misfiring, overheating, or losing power.