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GTECH Calibration
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P0455

Missing fuel cap, Defective or damaged fuel cap, Distorted or damaged Fuel Tank Filler Neck, Torn or punctured Evaporative system hose(s), Defective Fuel Tank Sending Unit gasket or seal, Split or damaged Carbon Canister, Defective Evaporative Vent Valve and or Evaporative Purge Valve, Defective or damaged fuel tank, Defective Fuel Tank Pressure Sensor.

  • Audi
  • Powertrain
  • Generic code
  • Low severity

How this code is built

P
SystemPowertrain
0
Defined bySAE, the same on every car
4
AreaAuxiliary emission controls
55
FaultThe specific fault in that area

What it means

P0455 means the control unit has detected a large leak in the evaporative emission (EVAP) system, which captures fuel vapour from the tank and feeds it to the engine. The unit runs a leak test by sealing the system and checking whether pressure or vacuum holds. On this Audi the test failed, or the system could not be sealed at all, so the fault was stored. The most common culprit is a fuel cap that is missing, loose or damaged.

Symptoms

  • Engine management light on
  • Fuel smell around the car or near the filler
  • No noticeable change in driving or performance
  • Fuel cap warning or message on some models
  • Failed emissions test at inspection

Possible causes

  • Fuel cap missing, loose, damaged or with a worn seallikely
  • Distorted or damaged fuel filler neck, or a poor seal at the fillerpossible
  • Split, disconnected or perished EVAP hose or pipelikely
  • Stuck-open or faulty purge valve or EVAP vent valvelikely
  • Cracked or damaged carbon canisterpossible
  • Leaking fuel tank sender unit seal or gasketpossible
  • Faulty fuel tank pressure sensor or damaged fuel tankrare

How to diagnose

  1. Read the stored codes and freeze frame data, and note whether other EVAP or fuel trim codes are present and when the fault was set
  2. Check the fuel cap is present, tightens properly, and the seal is intact and not cracked, then clear the code and see if it returns after a drive cycle
  3. Inspect the filler neck and the area around it for damage, corrosion or distortion that stops the cap sealing
  4. Visually inspect all accessible EVAP hoses, pipes, quick-release connectors and the canister for splits, disconnections or damage
  5. Using diagnostic equipment, command the purge valve and vent valve and check they open and close and that their wiring and connectors are sound
  6. Check the purge valve for a stuck-open condition by testing whether it holds vacuum when not commanded
  7. Carry out a smoke test of the EVAP system to locate the leak, following the procedure for the specific model and engine
  8. Check the tank pressure sensor reading against expected values with the system at ambient pressure, and inspect the sender unit seal

How to fix

  • Fit a correct, good-quality fuel cap if the old one is missing, damaged or has a worn seal
  • Repair or replace the damaged filler neck or its seal
  • Replace split, perished or disconnected EVAP hoses, pipes or connectors
  • Replace the faulty purge valve or vent valve, and repair any wiring or connector faults
  • Replace a damaged carbon canister or the leaking tank sender unit seal
  • Replace a faulty tank pressure sensor, or repair or replace the fuel tank if it is damaged

Can I keep driving?

Low severity

The car is generally safe to drive and the fault does not usually affect performance. Book it in soon, as a fuel vapour leak can cause a fuel smell and will fail an emissions test; if you smell raw fuel strongly or see liquid leaking, have it checked promptly.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.

This code for other makes

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