po 455 error code

gas cap is loose... retighten it

Error code 0455: A large leak has been detected in the evaporative

system. See TSB 25-001-02. Also, possible faulty or

loose gas cap. Note: The respective Powertrain

Diagnostic Procedures Manual will direct the technician

to determine if the vehicle evaporative system has an

external system leak. Examples of some external

system leaks are: a loose gas cap, a disconnected

evaporative system hose, or a loose hose connection.

Remember that the evaporative system may also have

an internal system leak. This internal leak may be

caused by an intermittent or permanently stuck open

Duty Cycle Purge (DCP) valve. This leak source is

considered to be internal because any escaping

emissions enter into the engine system and not directly

into the atmosphere, unlike an external leak. An internal

leak may cause one of the above DTC?s. Possible

causes of a stuck open (intermittent or permanent) DCP

valve are: 1. Corrosion due to system moisture or

possible water intrusion into the system.

P0455 _most_ often means the gas cap is not secured.

Yes, it does.

All codes from P0440 to P0459 are Evap Emissions Control malfunctions. Some can be a sensor or two that are not working right, but most are rooted in leaks that can be traced back to the gas cap. Sure, some are not the gas cap, but following the rule of fixing the cheapest and easiest thing first rule of automotive mechanics, the gas cap is the prime suspect in any of these codes.

And the P0455 code is a gross leak, what could possibly be more gross than the gas cap being left off, or put on askew?

P0440 Evaporative Emission Control System Malfunction P0441 Evaporative Emission Control System Incorrect Purge Flow P0442 Evaporative Emission Control System Leak Detected (small leak) P0443 Evaporative Emission Control System Purge Control Valve Circuit Malfunction P0444 Evaporative Emission Control System Purge Control Valve Circuit Open P0445 Evaporative Emission Control System Purge Control Valve Circuit Shorted P0446 Evaporative Emission Control System Vent Control Circuit Malfunction P0447 Evaporative Emission Control System Vent Control Circuit Open P0448 Evaporative Emission Control System Vent Control Circuit Shorted P0449 Evaporative Emission Control System Vent Valve/Solenoid Circuit Malfunction P0450 Evaporative Emission Control System Pressure Sensor Malfunction P0451 Evaporative Emission Control System Pressure Sensor Range/Performance P0452 Evaporative Emission Control System Pressure Sensor Low Input P0453 Evaporative Emission Control System Pressure Sensor High Input P0454 Evaporative Emission Control System Pressure Sensor Intermittent P0455 Evaporative Emission Control System Leak Detected (gross leak)

For what it is worth, I recently had the 0442 code which turned out to be the gas cap fit. After about 12 restarts the check engine light went off and now after a month or 2 the code is gone as well. I would see if the engine light goes away soon on its own if the gas cap replaced correctly. My data is on an 02 TJ. Tomes

A P0455 is a Gross Leak. This will be an open hose or a loose cap. The loose cap is the most common by a wide margin, and is the easiest to check and correct. Until one secures the gas cap, there is no point in looking at anything else.

I'm not arguing, I'm trying to get the OP on the right track to curing the problem. And, YOU haven't offered up anything other than, "no it doesn't," and "your own posting proves it." The fact is, my post all but comes right out and says, check the gas cap, and it offers up at the very least a direction to embark upon reasonable repairs.

If you have any specific suggestions beyond, "no it doesn't," please take a moment to write them down.

The link below takes you to pictures of what my 3 year old gas cap looked like inside in outside after it threw off the P0456 error code.

Chevron