2000 Ford Focus...DTC code PO455

code p 0455 refers to evaporative emission (EVAP) system--large leak===causes ---hose connections--intake leak---EVAP canister--EVAP canister purge valve
or simply-- the gas cap not on tight after a refill ( first check)

Most likely a bad fitting fuel cap, here is a link = P0455 Toyota EVAP System Gross Leak Detected

As you know one of the problems can be the Fuel Cap. I make this suggestion. If you changed your Fuel Cap before the Purge Valve double check that the cap used was an OEM (Original) Chevy Part for that specific vehicle, not just any cap from another Chevy.

P0455 is Evaporative Emissions System Leak Detected (Large) and means that there is a large leak in the system probably with one of the EVAP hoses near the fuel tank or EVAP canister or maybe even A leaky purge valve.

your code 455 is caused by a misfire. And the code 420 Is caused by what is called a evap leak. the most common cause of this code is the o ring in your gas cap leaking.

P0455 CHEVROLET - Evaporative Emission Control System Leak Detected Gross Leak3http://engine-codes.com/p0455_chevrolet.htmlForum CodePossible 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

The information you are asking for varies depending on how the vehicle is equipped ie. ENGINE SIZE, AUTOMATIC or MANUAL TRANSMISSION, 2-WHEEL DRIVE, 4-WHEEL DRIVE, ALL-WHEEL DRIVE, etc.
With that said, it also deserves mention that there is a Technical Service Bulletin published by Ford Motor Company that applies to the model year and model that you have listed that involves Diagnostic Test Code (DTC) P0456.

Please note that this bulletin emphasizes the requirement of special equipment to properly diagnose and repair the DTC's listed in the bulletin. Below is a brief (partial) description of the bulletin:

Article No.
03-20-3
10/13/03
DRIVEABILITY - MALFUNCTION INDICAOR LAMP
(MIL) ILLUMINATED WITH DTC'S P0442, P0455,
P0456, P0457, P1442 OR CHECK FUEL CAP LAMP
ILLUMINATED WITH DTC P0457
FORD: 1997-2000 CONTOUR 1997-2002 ESCORT 1997-2003 CROWN VICTORIA, MUSTANG, TAURUS 1998-2003 ESCORT ZX2 2000-2003 FOCUS 2002-2003 THUNDERBIRD1997 F-250 HD
1997-1999 F-250 LD
1997-2003 E SERIES, EXPEDITION, EXPLORER, F-150, RANGER, WINDSTAR
1999-2003 F SUPER DUTY
2000-2003 EXCURSION
2001-2003 ESCAPE, EXPLORER SPORT TRAC, EXPLORER SPORT
LINCOLN:
1997-1998 MARK VIII
1997-2002 CONTINENTAL
1997-2003 TOWN CAR
2000-2003 LS
1998-2003 NAVIGATOR
2002-2003 BLACKWOOD
MERCURY:
1997-1999 TRACER
1997-2000 MYSTIQUE
1997-2003 GRAND MARQUIS, SABLE
1999-2002 COUGAR
1997-2003 MOUNTAINEER
This article supersedes TSB 03-9-8 to update the vehicle lines and Service Procedures.
ISSUE
Some vehicles may exhibit a Malfunction Indicator Lamp (MIL) illuminated with Diagnostic Trouble Codes (DTCs) P0442, P0455, P0456, P0457 or P1442 or a "Check Fuel Cap" Lamp illuminated with DTC P0457 for the Evaporative Emission System. This may be caused by loose or leaking hoses, loose or broken fuel cap, a leak at the top of the fuel filler pipe neck, etc.
ACTION
Use the Rotunda Leak Detector Smoke Machine (Part 218-00001) or equivalent, to locate and repair leaks in the Evaporative Emission System.

Hi.

The DTC PO455 means "Evaporative System Emission Leak". The evaporative system is where gases evaporating from tank are collected and directed to the engine where they get mixed with fuel from pump and air.

P0455 is often caused by a defective fuel cap. The fuel system in your Beetle is pressurized. If the cap is defective it will allow gases and air out triggering the code.

Change the cap first.

If the fuel cap does not fix the problem then there is effectively a leak. That is usually caused by a broken evap system hose. In that case the parts in the evaporative system must be tested. The repair should not be expensive.

Regards.

Ginko

fuel system vent leak. not to worry it isn't dangerous, your vent line and gas line are different. A bad gas cap is most common cause. if after you change the cap and you use a scantool to clear the code, the light comes back on then you will need to do a smoke test to see where the leak is coming from.

code po455 means: EVAC Control System Leak Detected