Mitsubishi 98 faulty fuel cap, leaking vent or purge solenoid, evap hose faulty, leak on fuel tank, PO455

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
What does this mean? Tech notes
The P0455 it's a very common code, because the code is set if the gas cap is loose or missing. Start by tighten the gas cap and clearing the code. In most cases the code can be clear by disconnecting the car battery for about 30 minutes.
What does this mean? When is the code detected?
Evaporative Emission System (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 Mitsubishi Description
This diagnosis detects leaks in the Evaporative Emission System (EVAP) purge line using engine intake manifold vacuum. If pressure does not increase, the Engine Control Module (ECM) will check for leaks in the line between the fuel tank and EVAP canister purge volume control solenoid valve under the following vacuum test condition.
The vacuum cut valve bypass valve is opened to clear the line between the fuel tank and the EVAP canister purge volume control solenoid valve. The EVAP canister vent control valve will then be closed to shut the EVAP purge line off. The EVAP canister purge volume control solenoid valve is opened to depressurize the EVAP purge line using intake manifold vacuum. After this depressurization is implemented, the EVAP canister purge volume control solenoid valve will be closed.

Read more: http://engine-codes.com/p0455_mitsubishi.html#ixzz3NlVyARyX

codes po441 po442 po455 po456. code po441 - EVAP system no flow during purge conditions.code po442 -EVAP system small leak detected conditions. code po455 - EVAP system large leak detected conditions.code po456 - EVAP system very small leak detected. possible causes loose damaged missing fuel cap.fuel tank sensor disconnected or failed. ORING on top fuel sending unit leaking.purge valve vapor line clogged disconnected or purge solenoid failed.vent solenoid not closing or has failed.

PO455- EVAP System
Gross Leak or No purge Flow

Gas Cap -Bad or just not on tight

Cracked Hoses
Purge Valve Stuck Closed
Canister Vent Solenoid Stuck Open
Fuel Tank Pressure Sensor

Check that gas cap is on, then after that
a repair shop

This alarm concerns the function of the EVAP SYSTEM. This system monitors vacuum correctness. If a sufficient vacuum level cannot be achieved, a large leak or a faulty EVAP canister purge solenoid is indicated. It can be caused for the following reasons:
1) Disconnected or faulty fuel tank pressure sensor
2) Missing or faulty fuel cap
3) Disconnected, damaged, pinched, or blocked EVAP purge line.
4) Disconnected or damaged EVAP vent hose.
5) Disconnected, damaged, pinched, or blocked fuel tank vapor line.
6) Disconnected or faulty EVAP canister purge solenoid.
7) Disconnected or faulty EVAP canister vent solenoid.
8) Damaged EVAP canister.
9) Leaking fuel sender O-ring.
10) Leaking fuel tank or fuel filler neck.

P0456 - Evaporative Emissions System - Small leak detected
The Powertrain Control Module (PCM) at different times performs various tests on the EVAP system. OBD II Enhanced EVAP systems are in place to keep fuel tank vapors from venting into the atmosphere, and instead purges them into the engine to be burned. Regular pressure tests are conducted by the PCM to monitor the sealed system for leaks. The PCM monitors the EVAP system pressure by watching the fuel tank pressure (FTP) sensor. When the sensor indicates a small leak in the EVAP system, this code is set.
Potential Symptoms

There will likely be no noticeable symptoms other than the Malfunction Indicator Lamp (MIL). This is because the EVAP system is a closed system and only controls fuel tank vapors, not engine management.

Causes: Usually this P0456 code is caused by an incorrect or faulty gas cap. Filling the fuel tank with the engine running could conceivable cause this code as well or if the cap wasn't properly tightened. Any of the following could also be the cause:
* A small leak in any of the EVAP hoses or fuel tank hoses
* A small leak in the purge valve or vent valve
* The EVAP Canister may be leaking

Possible Solutions: First, using a scan tool activate the vent solenoid, sealing the system. Then monitor the fuel tank pressure (FTP) sensor. If the system is sealing properly, the number will stay consistent. If is isn't, the pressure sensor will show that as well. If the system slowly leaks, use a smoke machine and watch for smoke exiting the system at any EVAP component. Any where there is smoke exiting the system, that is the faulty component. Do not pressurize the EVAP system with air pressure. Doing so can damage the purge and vent solenoids in the system.


Hope this helps.

The PCM monitors vacuum level via the fuel tank pressure sensor input. At an appropriate time, the EVAP purge solenoid and the EVAP vent solenoid are turned on, allowing engine vacuum to draw a small vacuum on the entire evaporative emission system. After the desired vacuum level has been achieved, the EVAP purge solenoid is turned off, sealing the system. A leak is detected by monitoring for a decrease in vacuum level over a given time period, all other variables remaining constant. A large leak in the system causes DTC P0445 to be set.

If the desired vacuum level cannot be achieved in the test described above, a large leak or a faulty EVAP purge solenoid is indicated. This can be caused by the following conditions:

*Disconnected or faulty fuel tank pressure sensor.

*Missing or faulty fuel cap.

*Disconnected, damaged, pinched, or blocked EVAP purge line.

*Disconnected or damaged EVAP vent hose.

*Disconnected, damaged, pinched, or blocked fuel tank vapor line.

*Disconnected or faulty EVAP canister solenoid.

*Disconnected or faulty EVAP vent solenoid.

*Open ignition feed circuit to the EVAP vent or purge solenoid.

*Damaged EVAP canister.

CODE PO455 - EVAP SYSTEM LARGE LEAK DETECTED CONDITIONS.POSSIBLE CAUSES FUEL CAP LOOSE MISSING,FUEL TANK FULLER NECK OR FUEL SENDING UNIT O - RING IS LEAKING, FUEL TANK PRESSURE SENSOR IS DAMAGED,FUEL TANK VAPOR LINES,CLOGGED,DAMAGED,OR DISCONNECTED,PURGE VALVE VAPOR LINE IS CLOGGED,DAMAGED,OR DISCONNECTED,PURGE SOLENOID IS NOT OPENING,IT MAY BE DAMAGED OR STICKING,VENT SOLENOID IS NOT CLOSING,MAY BE DAMAGED OR STICKING,PCM HAS FAILED.

CODE PO455 EVAPORATIVE EMISSION SYSTEM LARGE LEAK DETECTED.POSSIBLE CAUSES CANISTER VENT SOLENOID MAY BE STUCK IN OPEN POSITION / EVAP CANISTER TUBE EVAP CANISTER PURGE OUTLET TUBE OR EVAP RETURN TUBE DISCONNECTED OR CRACKED OR CANISTER IS DAMAGED / EVAP CANISTER PURGE VALVE STUCK CLOSED OR CANISTER DAMAGED / FUEL FILLER CAP MISSING LOOSE NOT TIGHT OR THE WRONG PART / FUEL VAPOR HOSES TUBES BLOCKED OR RESTRICED OR FUEL VAPOR CONTROL VALVE TUBE OR FUEL VAPOR VENT VALVE ASSEMBLY BLOCKED /FUEL TANK PRESSURE SENSOR HAS FAILED MECHANICAL FAULT /FUEL TANK CONTROL VALVE IS CONTAMINATED DAMAGED OR HAS FAILED.

It will not go off by itself,you will need to reset it by connecting to a diagnostic tool.Once cleared if there is any other problem then it will trigger the check engine light again.Hope this helps..

Hello shoretex...Yes sir you can repair this yourself...
p0442 is medium leak detected ...p0456 is small leak....and p0440 is a general evap system failure.. evap codes are a common thing. gas caps are an inexpensive place to start. There are two types of evap hoses on the Dodge... hard plastic and soft rubber.... before you replace parts check the soft rubber first at the evap cans and pump located about a foot in front of the gas tank fill pipe on trucks located next to the transfer case or right behind the trans on the driver side. hard plastic lines will brake or rub through...check spots where lines come in contact with anything. this is a common thing with older trucks...hair line cracks will kick a p0442 code, and a p0445 code...When you find a leak, repair it, and rescan...sometimes there are several leaks, continue with inspection and repairs until you get it all fixed up.... Remember..start at simple and work from there...
i will post the evap. system in more detail to help you troubleshoot the problem.
EVAP System: The Evaporative Emission (EVAP) Control system used on all vehicles is the charcoal canister storage method. This method transfers fuel vapor from the fuel tank to an activated carbon (charcoal) storage device (canister) to hold the vapors when the vehicle is not operating. When the engine is operating, the fuel vapor is purged from the carbon element by intake air flow and consumed in the normal combustion process. The evaporative system includes the following components: *Fuel tank *Evaporative emission canister vent solenoid *Fuel tank pressure sensor *Fuel pipes and hoses *Vapor lines *Fuel cap *Evaporative emission canister *Purge lines *Purge valve solenoid EVAP System Operation: The EVAP purge solenoid valve allows manifold vacuum to purge the canister. The Powertrain Control Module (PCM) supplies a ground to energize the EVAP purge solenoid valve (purge on). The EVAP purge solenoid control is Pulse Width Modulated (PWM) or turned on and off several times a second. The EVAP canister purge PWM duty cycle varies according to the operating conditions determined by the mass air flow, the fuel trim, the engine coolant temperature, and the intake air temperature. For certain EVAP tests, the diagnostic will be disabled if the TP angle increases to above 75% . The evaporative leak detection diagnostic strategy is based on applying vacuum to the EVAP system and monitoring for vacuum decay. The fuel level sensor input to the PCM is used to determine if the fuel level in the tank is correct to run the EVAP diagnostic tests. To ensure sufficient volume in the tank to begin the various diagnostic tests, the fuel level must be between 15% and 85% . The PCM monitors the fuel tank pressure/vacuum level via the fuel tank pressure sensor input. Results of Incorrect Operation: Poor idle, stalling and poor driveability can be caused by the following: *Malfunctioning purge solenoid. *Damaged canister. *Hoses/lines split, cracked and/or not connected properly. Evidence of fuel loss or fuel vapor odor can be caused by the following: *Liquid fuel leaking from the fuel lines *Cracked or damaged canister *Inoperative canister control valve Vacuum hoses that are: *Disconnected *Mis-routed *Kinked *Deteriorated *Damaged The evaporative leak detection diagnostic strategy is based on applying vacuum to the EVAP system and monitoring vacuum decay. The PCM monitors vacuum level via the fuel tank pressure sensor input. At an appropriate time, the EVAP purge solenoid and the EVAP vent solenoid are turned on, allowing engine vacuum to draw a small vacuum on the entire evaporative emission system. After the desired vacuum level has been achieved, the EVAP purge solenoid is turned off, sealing the system. A leak is detected by monitoring for a decrease in vacuum level over a given time period, all other variables remaining constant. A small leak in the system causes DTC P0442 to be set. If the desired vacuum level cannot be achieved in the test described above, a large leak or a faulty EVAP purge solenoid is indicated. This can be caused by the following conditions: *Disconnected or faulty fuel tank pressure sensor. *Missing or faulty fuel cap. *Disconnected, damaged, pinched, or blocked EVAP purge line. *Disconnected or damaged EVAP vent hose. *Disconnected, damaged, pinched, or blocked fuel tank vapor line. *Disconnected or faulty EVAP canister solenoid. *Disconnected or faulty EVAP vent solenoid. *Open ignition feed circuit to the EVAP vent or purge solenoid. *Damaged EVAP canister. Any of the above conditions sets DTC P0440. A restricted or blocked EVAP canister vent path is detected by drawing vacuum into the EVAP system. The PCM turns off the EVAP vent solenoid and the EVAP purge solenoid (EVAP vent solenoid Open, EVAP purge PWM 0% ). The PCM monitors the fuel tank pressure sensor input. With the EVAP vent solenoid open, any vacuum in the system should decrease quickly unless the vent is blocked. A blockage is caused by the following conditions: *Faulty EVAP vent solenoid (stuck closed). *Plugged, kinked, or pinched vent hose. *Shorted EVAP vent solenoid driver circuit. *Plugged evaporative canister.

Good luck shoretex, hope this helps...please take time to rate me a fixya.