Question about 2002 Jeep Wrangler

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2002 jeep wrangler 6 cylinder: error codes P0455 and P0442: replaced gas cap: removed, taped, and reinstalled hoses to what i believe is the evap canister. what else could be wrong? it still idles rough...what about the leak detection pump or purge valve? how long will it take for the codes to go away? where can i get an engine diagram that clearly shows the parts? the haynes manual is less than helpful.

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  • james_laxton Nov 14, 2010

    can you tell me where i can get an engine diagram that shows the evap system and its parts for a 2002 jeep wrangler 4.0 6 cylinder?

  • james_laxton Nov 14, 2010

    Thanks. This is exactly the set-up on my jeep. I will double check to make sure all of the hoses and connections are ok. Is there an easy way to test the ldp, ldp filter, and the evap purge solenoi? How do know if the evap test port is in the correct position? Should the parts listed above be available at the auto parts store in case I need to replace them?

    JL

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THE P0455 CODE POSSIBLE CAUSES ARE

  • Leak at Gas Cap
  • Vehicle History and Service Bulletin Investigation
  • Visual and Physical Inspection
  • Verify Evaporative Emission Leak
  • EVAP Purge Solenoid Operation
  • Intermittent LDP Monitor Failure
  • Evaporative Emission Leak Detection
  • Gas Cap
  • LDP Component Leak
WHAT ENGINE DIAGRAMS I HAVE IS BELOW WITH DEFINITIONS
  • 2002 jeep wrangler 6 cylinder: - dak408_24.gif
On 4.0L 6 cylinder engines, a molded vacuum tube connects manifold vacuum to top of cylinder head (valve) cover at dash panel end. The vacuum fitting contains a fixed orifice of a calibrated size. It meters the amount of crankcase vapors drawn out of the engine.

On 2.5L 4 cylinder engines, a fitting on drivers side of cylinder head (valve) cover contains the metered orifice. It is connected to manifold vacuum.

A fresh air supply hose from the air cleaner is connected to front of cylinder head cover on 4.0L engines. It is connected to rear of cover on 2.5L engines.

When the engine is operating, fresh air enters the engine and mixes with crankcase vapors. Manifold vacuum draws the vapor/air mixture through the fixed orifice and into the intake manifold. The vapors are then consumed during combustion.

EVAP/PURGE SOLENOID
The duty cycle EVAP canister purge solenoid (DCP) regulates the rate of vapor flow from the EVAP canister to the intake manifold. The Powertrain Control Module (PCM) operates the solenoid.

During the cold start warm-up period and the hot start time delay, the PCM does not energize the solenoid. When de-energized, no vapors are purged. The PCM de-energizes the solenoid during open loop operation.

The engine enters closed loop operation after it reaches a specified temperature and the time delay ends. During closed loop operation, the PCM cycles (energizes and de-energizes) the solenoid 5 or 10 times per second, depending upon operating conditions. The PCM varies the vapor flow rate by changing solenoid pulse width. Pulse width is the amount of time that the solenoid is energized. The PCM adjusts solenoid pulse width based on engine operating condition.

FUEL FILLER CAP
The plastic fuel tank filler tube cap is threaded onto the end of the fuel fill tube Certain models are equipped with a 1/4 turn cap.

The loss of any fuel or vapor out of fuel filler tube is prevented by the use of a pressure-vacuum fuel fill cap. Relief valves inside the cap will release fuel tank pressure at predetermined pressures. Fuel tank vacuum will also be released at predetermined values. This cap must be replaced by a similar unit if replacement is necessary This is in order for the system to remain effective.

CAUTION: Remove fill cap before servicing any fuel system component to relieve tank pressure. If equipped with a California emissions package and a Leak Detection Pump (LDP) , the cap must be tightened securely. If cap is left loose, a Diagnostic Trouble Code (DTC) may be set.

LEAK DETECTION PUMP
The Leak Detection Pump (LDP) is used only with certain emission packages

The LDP is a device used to detect a leak in the evaporative system.

The pump contains a 3 port solenoid, a pump that contains a switch, a spring loaded canister vent valve seal, 2 check valves and a spring/diaphragm.

Immediately after a cold start, engine temperature between 40 °F and 86 °F , the 3 port solenoid is briefly energized. This initializes the pump by drawing air into the pump cavity and also closes the vent seal. During non-test test conditions, the vent seal is held open by the pump diaphragm assembly which pushes it open at the full travel position. The vent seal will remain closed while the pump is cycling. This is due to the operation of the 3 port solenoid which prevents the diaphragm assembly from reaching full travel. After the brief initialization period, the solenoid is de-energized, allowing atmospheric pressure to enter the pump cavity. This permits the spring to drive the diaphragm which forces air out of the pump cavity and into the vent system. When the solenoid is energized and de-energized, the cycle is repeated creating flow in typical diaphragm pump fashion. The pump is controlled in 2 modes:

Pump Mode: The pump is cycled at a fixed rate to achieve a rapid pressure build in order to shorten the overall test time.

Test Mode: The Solenoid Is Energized With A Fixed Duration Pulse. Subsequent fixed pulses occur when the diaphragm reaches the switch closure point.

The spring in the pump is set so that the system will achieve an equalized pressure of about 7.5 inches of water.

When the pump starts, the cycle rate is quite high. As the system becomes pressurized pump rate drops. If there is no leak the pump will quit. If there is a leak, the test is terminated at the end of the test mode.

If there is no leak, the purge monitor is run. If the cycle rate increases due to the flow through the purge system, the test is passed and the diagnostic is complete.

The canister vent valve will unseal the system after completion of the test sequence as the pump diaphragm assembly moves to the full travel position.

VACUUM LINES
A vacuum schematic for emission related items can be found on the VECI label. Refer to Vehicle Emission Control Information (VECI) Label for label location

dak408_25.gif
VAPOR CANISTER
The evaporative (EVAP) canister is located in the engine compartment on the left inner fender.

A maintenance free, EVAP canister is used on all vehicles. The EVAP canister is filled with granules of an activated carbon mixture. Fuel vapors entering the EVAP canister are absorbed by the charcoal granules.

Fuel tank pressure vents into the EVAP canister. Fuel vapors are temporarily held in the canister until they can be drawn into the intake manifold. The duty cycle EVAP canister purge solenoid allows the EVAP canister to be purged at predetermined times and at certain engine operating conditions.

ONE WAY TO CLEAR ENGINE CODES WITH OUT HAVING A DIAGNOSTIC COMPUTER IS UN PLUG THE BATTERY AND LEAVE IT SIT FOR ROUGHLY 20 MINUTE AND REHOOK UP THIS MIGHT CLEAR THE CODES WITH OUT A COMPUTER.. BUT IF THE PROBLEM ISN'T FIXED THE CODES WILL SHOW AGAIN..


HOPE THIS HELPS

Posted on Nov 14, 2010

  • Dak408
    Dak408 Nov 14, 2010

    Local parts store might have the part and to test it you will need a ohm meter to check resistance and a vacuum pump..

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Hello
In the case of evaporative emission systems leak codes P0442 and P0455 (small and large leak) it is nearly impossible to know what leaking and causing the codes without using a special piece of equipment called a smoke leak detector, smoke is injected into the evaporative control system and then you look smoke escaping, the machines are very expensive but worth every penny, if no leaks are found after doing the smoke tests you can assume that the pressure sensor that is on the top of the fuel tank is defective, this gives the PCM (Powertrain Control Module) a false reading and that is interpreted as a leak which generates the codes. So in closing my advice to you is have a shop run the leak detection test with the smoke machine, it is worth every penny, it is doubtful without this test that you will easily find the leak if that is the problem, the test is not that expensive to have run, call around for estimates, thy can vary widely. Have a good day.

Posted on Nov 14, 2010

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Posted on Jan 02, 2017

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SOURCE: 2002 wrangler 4.0 6 cylinder

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Here is a picture of the canister and all the other parts.Let me know if this worked for you.One other thing is if you have a leak taping it will not keep it from leaking.You will have to replace the part that is leaking or not working properly.Let me know how this picture works out.This is the first time I have tried this.Good luck and thanks for using fixya.

Posted on Nov 13, 2010

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2 Answers

Error codes p0442 and po445


Po442 is evap system leak
check intake and all vacuum hoses for leaks
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Po445 is evap canister purge valve short circuit
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OBD code P0442 Small EVAP leak detected you may need to check the EVAP canister under the vehicle and the purge valve as well check for cracks on the canister or the purge valve and check all the rubber hoses connected to them foe cracks or holes. If you find any damage parts replace them. P0455 which means a large EVAP leak is sometimes referred as the gas cap leak check your gas cap and secure it tight if you still have the code change the gas cap hope this helps after you find and fix the problems get the vehicle to a shop and they will use an OBD scan tool to clear the codes.

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My malfunction indicator light is on dodge neon 2001: got codes P1684,P0455


this obd2 trouble code table can help you understand the meaning of code.
and for p0455, you can try:

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

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P0455 and p0442


p0455-- emission control system ( a large leak ) the most common cause is a bad seal on fuel cap, remove and replace cap, if light stats on. replace cap. if not the cap it could be any where in emission system. p0442 is--same as above. Code p0442 indicates a fuel vapor leak in the EVAP control system. To fix this problem, remove and reinstall the gas cap. Clear the codes and drive to see if the codes reappear. If the code appears again replace the gas cap or inspect the system for cuts or holes in the tube or hose. good-day !

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P0449 and P0455 error code 2008 2wd gmc envoy 30,203 miles


P0449 - Evaporative Emission Control System Vent Valve/Solenoid Circuit Malfunction

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

Both are refer at EVAP system; other EVAP DTCs: P0440 - P0441 - P0442 - P0443 - P0446 - P0453 - P0455 - P0456

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: 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: 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


Hope helps.

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1 Answer

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This indicates a fuel vapor leak in the EVAP control system. It means a very small leak has been detected. In fact, the leak can be from a hole as small as 0.04" in diameter. 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 P0442 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)
* A small leak/hole in a fuel vapor hose/tube
* Other small leak in EVAP system
* Faulty vent o-ring seal

Possible Solutions: with a P0442, 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, or
* Inspect the EVAP system for cuts/holes in tubes/hoses



P0445 - Evaporative Emission Control System Purge Control Valve Circuit Shorted.
Possible Solutions: with a P0445, the most common repair is to:
* Bad or loss contact wires
* Check harnesses, replace it


Hope helps (remember to rate this).

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I am getting a P0442 trouble code on my 2002 Jeep Wrangler. I have replaced the gas cap and one kinked line. But i still ge the light about once a month. What can i do to fix it? i have had the jeep at a...


Same problem on my 2001 TJ. Replaced cap, passed smoke test, supposed pinched hose fixed etc; light kept coming back on usually right after a cold start every other week or so. Three months later after trip to dealer and $367, it was due to an intermittenent evap cannister purge solenoid.

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2003 Jeep Liberty


p0455 is evap control system no purge or large leak
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the cause for both could actually be a loose gas cap.

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1 Answer

Code P0442 Engine Light


Causes A code P0442 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)
  • A small leak/hole in a fuel vapor hose/tube
  • Other small leak in EVAP system
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Possible Solutions With a P0442, 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, or
  • Inspect the EVAP system for cuts/holes in tubes/hoses

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