In the test of computer the cod is p0455(system -large leak

Question edited for clarity. P codes for DTCs must have upper case P.

All questions need FULL 'year make model'.

White smoke is steam, and this is normal at this time of year and is mentioned on this website a LOT at this time of year. Gasoline has weather in it at molecular level and is burned off as steam.

P0300 unknown random misfire
P0303 Misfire on Cylinder 3
P0304 As above on 4

OBD-II Trouble Code - P0455

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OBD-II code P0455 is a problem with an Evaporative Emission Control System Leak. Get expert information on fault code P0455.

P0455 Code: Evaporative Emission Control System Large ...

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Aug 6, 2023 - Code P0455 is typically triggered when your vehicle's computer detects a large leak in the EVAP system. Symptoms of a P0455 include a lit check ... Videos

2:20
How to Fix P0455 Engine Code in 3 Minutes [2 DIY Methods ...
YouTube · nonda 2 minutes, 20 seconds
Oct 21, 2020

The evap port is for checking pressure and vacuum in the fuel system storage system.It is a great place to pressurize the fuel system with smoke to find a leak.If you have a p0455 code you should pressurize your system with smoke and you will find your "large leak" code p0455 easily.(usually a stuck open vent valve when it has been commanded to close) It is normally in an open state for most driving so you will have to command it closed for testing.

P0455 - large leak - take to a qualified repair shop an have smoke tested .
EVAP Leak Testing P0455 Gross Leak

There is no one fix for this fault, you need a smoke test done to see if there really is a leak or it is a sensor malfunction, that takes a skilled tech to figure out what and which is the cause. This code can be a real nightmare to diagnose..

P1684 - Battery Disconnected Within Last 50 Starts

P0455 - Evaporative Emission Control System Leak Detected (no purge flow or large leak)
This indicates a fuel vapor leak or lack of purge flow in the EVAP control system. It means a large leak has been detected. The (EVAP) emission control system prevents the escape of fuel vapors from a vehicle's fuel system. Fuel vapors are routed by hoses to a charcoal canister for storage. Later, when the engine is running a purge control valve opens allowing intake vacuum to siphon the fuel vapors into the engine.

Symptoms: You likely won't notice any drivability problems.

Causes: A code p0455 most likely means one or more of the following has happened:
A loose or improperly affixed gas cap
A non-conforming gas cap (i.e. not factory/original brand)
Other leak or damaged piece in EVAP system

Possible Solutions: With a p0455, the most common repair is to:
Remove and reinstall the gas cap, clear the codes, and drive for a day and see if the codes come back.
Otherwise, replace the gas cap, and/or
Inspect the EVAP system for cuts/holes in tubes/hoses (you may hear a vacuum noise or smell fuel), repair if necessary


Test and check it. Hope this helps.

P0455 Evaporative emmission control leak (gross leak). Here is the main possiblity the gas cap is out, or you filled up the fuel tank with the car running, because its a large leak you can visually inspect the fuel refill hose, If you have a shop that can inspect this for you they can find it .

DTC P0455 - Evaporative Emission Control System Leak Detected (no purge flow or large leak)

This indicates a fuel vapor leak or lack of purge flow in the EVAP control system. It means a large leak has been detected. The (EVAP) emission control system prevents the escape of fuel vapors from a vehicle's fuel system. Fuel vapors are routed by hoses to a charcoal canister for storage. Later, when the engine is running a purge control valve opens allowing intake vacuum to siphon the fuel vapors into the engine.

Symptoms: You likely won't notice any drivability problems.

Causes: A code p0455 most likely means one or more of the following has happened:
* A loose or improperly affixed gas cap
* A non-conforming gas cap (i.e. not factory/original brand)
* Other leak or damaged piece in EVAP system

Possible Solutions: With a p0455, the most common repair is to:
* Remove and reinstall the gas cap, clear the codes, and drive for a day and see if the codes come back.
* Otherwise, replace the gas cap, and/or
* Inspect the EVAP system for cuts/holes in tubes/hoses (you may hear a vacuum noise or smell fuel), repair if necessary

Test it and send us news.

P0455 - Evaporative Emission Control System Leak Detected (no purge flow or large leak)

This indicates a fuel vapor leak or lack of purge flow in the EVAP control system. It means a large leak has been detected. The (EVAP) emission control system prevents the escape of fuel vapors from a vehicle's fuel system. Fuel vapors are routed by hoses to a charcoal canister for storage. Later, when the engine is running a purge control valve opens allowing intake vacuum to siphon the fuel vapors into the engine.

Symptoms: You likely won't notice any drivability problems.

Causes: A code p0455 most likely means one or more of the following has happened:
* A loose or improperly affixed gas cap
* A non-conforming gas cap (i.e. not factory/original brand)
* Other leak or damaged piece in EVAP system

Possible Solutions: With a p0455, the most common repair is to:
* Remove and reinstall the gas cap, clear the codes, and drive for a day and see if the codes come back.
* Otherwise, replace the gas cap, and/or
* Inspect the EVAP system for cuts/holes in tubes/hoses (you may hear a vacuum noise or smell fuel), repair if necessary

Test it and tell us news.

P0455 is a large leak detected in the evap system for your fuel. You need to have a smoke test done on this to locate leak

P0455 = EVAP LEAK MONITOR LARGE LEAK DETECTED. I am not sure if you are talking about a Jeep Grand Cherokee or a Chrysler 300M but the code is the same for all cars. This code referes to the gas vapor system on the vehice. Cars today take the gas vapor and instead of venting to the atmosphere they store and re-direct these gases back to the engine to be burned. The EPA mandated that the cars computer test the system for leaks. It does this with a series of valves to seal the system then depending on the system creates pressure and watches for a drop in pressure over a certian amount of time. If it drops too fast the P0455 code is stored and the check engine light comes on. I will tell you that these types of codes even for me take a while to find. There are however usually 3 things that can be the problem. The Natural vaccum leack dection pump, a bad or leaking hose in the system, or the purge valve. You might be better off taking it to a mechanic you can trust to have checked out.