Evaporative Emission Control System Leak Detected Gross Leak


Table of contents

P0455 MERCURY Possible Causes

  • Missing or loose fuel cap
  • Incorrect fuel filler cap used
  • Fuel filler cap remains open or fails to close
  • Foreign matter caught in fuel filler cap
  • EVAP canister or fuel tank leaks
  • EVAP system hose leaking
  • Fuel tank leaking

How do I fix code P0455 MERCURY?

  Check the “Possible Causes” listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector’s pins.

Tech Notes

  • The P0455 is a common code since it will set if the gas cap is loose or missing. Start by tightening the gas cap and clearing the code. In most cases, the code can be clear by disconnecting the car battery for about 30 minutes.
  • There is a factory service bulletin for the following Mercury vehicles:
  • 1997-1999 Mercury Tracer
  • 1997-2000 Mercury Mystique
  • 1997-2003 Mercury Grand Marquis
  • 1997-2003 Mercury Sable
  • 1999-2002 Mercury Cougar
  • 1997-2003 Mercury Mountaineer
  • Mercury Factory Service Bulletin OBDII Code P0455

Cost of diagnosing the P0455 MERCURY code

  The cost of diagnosing the P0455 MERCURY code is 1.0 hour of labor. The auto repair labor rates vary by location, your vehicle’s make and model, and even your engine type. Most auto repairs shops charge between $75 and $150 per hour.

When is the code detected

  EVAP control system has a very large leak such as fuel filler cap fell off, EVAP control system does not operate properly.

Possible Symptoms

  • Engine Light ON (or Service Engine Soon Warning Light)
  • Possible a noticeable fuel odor caused by the release of fuel vapors

P0455 MERCURY Description

  Vehicles that meet enhanced evaporative requirements utilize a vacuum-based evaporative system integrity check. The EVAP system integrity check uses a Fuel Tank Pressure Transducer (FTPT), a Canister Vent Solenoid (CVS) and Fuel Level Input (FLI) along with the Vapor Management Valve (VMV) or Electric Vapor Management Valve (EVMV) to find 0.040″ diameter or larger EVAP system leaks. Federal vehicles can utilize a 0.040″ leak check rather than the 0.020″ leak check required for California vehicles.
The Diagnostic Trouble Code (DTC) will set when the EVAP control system has a very large leak such as the fuel filler cap fell off, the EVAP control system does not operate properly.

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