Question about 2000 Jeep Grand Cherokee

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P1494 code hi my check engine light came on so we thought it might be the gas cap so we replaced it and had the light turned back off well it came on again and gave this code i looked it up and it says leak detection pump switch or mechanical fault so what exactly does that mean? what do i have to do to fix it and how much do you think it would cost thanks Beth

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  • bcripps Aug 07, 2008

    same as beth

  • Anonymous Mar 21, 2014

    I just want to know how much would all this cost


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It means you aren't tightening the gas cap down tight, or the vent in the gas cap isn't sealing. Open the gas cap, and look at the center. Take a punch and jiggle the center, which is a valve. This will usually re-seat the valve... or replace the cap. Every so often the computer will pump air into the fuel tank to determine if there's a poor seal in the air space above fuel. If it doesn't find pressure holding, then the error code is logged.

Posted on Aug 08, 2008

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P1494 code

engine idle speeds, odd, hot? any real symptoms?

can be lots of things, the FSM covers it.
I think the ratio to real EVAP faILuers TO BAD CAP , IS LIKE 1000000:1 its so bad , new cars put , gas cap failure on dash !! display.
Give that fact, check cap first, and reset the ECU.
the EVAP system can be simple or hard.
Visual check the vacuum lines to all EVAP components
check all fuses.
then make sure gas cap is tight. (if cracked its no good) or a bad seal.
the reset the codes, using any scan tool. ($9 tool)
drive for a week see if it comes back, if comes back then its REAL.
if there is breach in the EVAP or bad VSV, (vacuum sol. valve)
then that takes the testing steps in the FSM.
or the EVAP system needs pressure testing, like they do
in all smog stations , at the cap.
if the leak down test fails, then you simply find that leak.
On can use any rubber tube held to the ear to hear a leak (after using a pressures source to the system.
if you have no tools, take it in. if DIY , buy them.
read the FSM. under this code, and the EVAP sections carefully.
there are 2 paths, it really is failing the EVAP or the OBD2 testing parts
are fibbing.
lots of guessing here, no tests...

the EVAP system , keeps gas fumes from polluting the air we breath.
it seals the tank vents and burns off all fumes as you drive.
that is what it does.
and is tested, all the time by the OBD2 system.
its very reliable in finding, any failure.
Your system fails the first step, it checks to see if the system
even holds pressure, and fails. the FSM explains how this
test is conducted, the steps and checks.

Cap issues?
my current jeep , the cap ratchet was dead. and would not get fully tight.
or the vacuum breaker inside is bad. (stuck open)
or the sealing ring is bad.
or someone put wrong cap on car.
or a locking cap that is wrong.
the cap holds pressure, and never a vacuum.
the vacuum breaker prevents fuel tank collapes (photos avail)

Dec 25, 2013 | 1999 Jeep Grand Cherokee

2 Answers

Check engine light is on, and OT sensor code is P1494 was diagnosed.

P1494 - LEAK DETECTION PUMP SWITCH OR MECHANICAL FAULT . There is a service bulletin for certain years pertaining to this problem . Some cars will fill the vacuum line going to the LDP with oil , causing this dtc to trip . In most cases you can clear this and it won't come back-also, check your gas cap, it needs to seal the system, if it is loose or leaks, it can set this code.

Jan 30, 2011 | 2001 Dodge Dakota

4 Answers

What i do if it shows the word gascap and the engine light is on?

I know this is an old post... but I had this issue now. I wanted to put my experience out there. I have this car and sure enough, the gas cap light went off. I checked the cap and it was on perfect.. Then sure enough a couple days later my check engine light popped up. They ran my car in the system for the engine light and sure enough there were two evap codes that went off.. They thought it was just the gas cap but then looked into Chrysler known issues and they told me there was a service order for this model car where they need to replace two parts.. one is some kind of filter and something else (didnt pay attention to the name).. but I go back tomorrow to get it fixed. They set an hour appointment as its supposed to be an easy fix. Im hoping it improves gas efficiency some at least, too.

Dec 30, 2010 | 2007 Chrysler Sebring Sedan

2 Answers

Check engine light came on. Code P1456.

Did you change the gas cap with a Honda gas cap? Tighten it at least three clicks?
Also, Honda recommends that you never top off the tank when getting gas (only go to the click-off of the pump; otherwise you can get back flow into the system that will cause the code).
Tightening or replacing the cap will not immediately cause the light to go off; it can take up to three days of driving for the light to reset.
To check if your readiness codes (emission system) are set, turn the ignition to ON (II), without starting the engine. The Malfunction Indicator Lamp will come on for 20 seconds. If it then goes off, the readiness codes are set. If it blinks 5 times, the readiness codes are not set.
You can, of course, try resetting your engine light to see if it will come back on (which it probably will). I believe the procedure is:
Turn off the engine.
Press and hold the Select/Reset knob (odometer) in the instrument panel, then turn the ignition switch to ON (II).
Hold the knob for approximately ten seconds until the indicator resets.

Hope this helps you.

Nov 17, 2009 | 2004 Honda Pilot

2 Answers

Engine light on with code 1494runs ok for now but light want stay off when i have it taken off, was told it was sensor to motor, but that there was four different ones and they don't know which one it...

P1494 means Leak Detection Pump Switch or Mechanical Fault - This code appears when there's an issue with the EVAP System (fuel tank fumes) This can be caused by a improperly secured gas cap, faulty gas cap, crack in the vacuum line, etc.

Sep 17, 2009 | 2001 Jeep Grand Cherokee

2 Answers

Trouble codes

Evaporative Emission System Incorrect Purge Flow
Jeep: Leak detection pump pressure switch or mechanical fault
U either have a leaking fuel system or the pressure sensor at the gas tank is defective, I would replace the pressure sensor 1st.

Jul 02, 2009 | 2000 Jeep Cherokee

1 Answer

Fix P1494 code

This code is caused by the leak detection pump for the evaporative emissions control system, this is a common fault in your year and model, there are factory bullentins about the code, to replace the pump do the following. As noted in the procedure pay close attention to the condition of the vacuum lines to the pump.

The LDP, (leak detection pump) is located in the left/front corner of engine compartment below the air cleaner housing. It is mounted to left/front inner fender sheet metal. The LDP and LDP filter are replaced (serviced) as one unit.

Mar 04, 2009 | 2002 Jeep Grand Cherokee

2 Answers

Check Engine light on and transmission will not shift from low.

Did they erase them by any chance? 2 out of the 3 come up transmission related. Does it feel likes it shifting funny or hard or anything? Not sure if unhooking battery will work on that year or not but worth a try if vehicle seems to shift fine. Then if codes come back, have it checked and repaired at that time, it may be a simple update needed to computer.

Jan 02, 2009 | 2000 Dodge Caravan

2 Answers

OBDI 11 ERROR CODE P1494 EVAP leak detection pump pressure switch condition

This is gonna blow your mind: I had the same problem with my 02 Chev Blazer and braced myself for an awesomely expensive fix. I kept getting the same response from the experts, though: "you WILL NOT get an evap failure - did you forget to close your gas cap?"

Buy a new gas cap, then run your Jeep for a week or so. The air in your fuel system should work itself out and kill the check engine light.

Dec 12, 2008 | 2000 Jeep Grand Cherokee

1 Answer

Trouble code P1494

These are all related sensors and active devices of the evap system, clear the code and replace the fuel cap.

Nov 08, 2008 | 2002 Jeep Grand Cherokee

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