Check Engine Light Scan Question - Evap Purge Flow Sensor

**bmyohn** · 04-19-2007, 08:38 PM

My check engine light came on yesterday afternoon, so i took it to Auto Zone to get the codes read. The guy wasnt very helpful, he plugged it in a let me read what it said. Although, he did compliment the Jeep a lot, anyways, this is what the print out read,

"The PCM has determined that a malfunction exsists in the electrical circuit for the evap purge flow sensor"

what does that mean?

what does the Evap Purge Flow Sensor do?

can i fix it myself?

any tips would be great!!

Brendan

**bmyohn** · 04-19-2007, 09:25 PM

bump...any ideas guys??

lost honda pro · 04-19-2007, 10:05 PM

the evaporative emissions control systems on OBDII vehicles circulates the gasoline vapor from above the liquid gasoline in the fuel tank as to 1) get more efficiency, and 2) be nice to the environment. these gas vapors are sucked into a charcoal canister in the engine bay (not sure where on the jeeps) and the EVAP purge sensor controls when the valve opens so the intake manifolds vacuum can suck the gas vapors into the engine to be burned.

check the wiring for any sensors from the charcoal canister to the intake manifold, and if all the wiring checks out, clean the hoses out really good, and then test the harness plugs for proper voltage/ground, and if that all checks out, buy a new purge sensor.

**bmyohn** · 04-20-2007, 06:37 AM

alright, thanks for ur help, i will definetly look into that today

thanks for ur help

Brendan

lost honda pro · 04-20-2007, 10:01 AM

no prob...

**bmyohn** · 04-20-2007, 10:03 AM

does anyone know where the charcoal canister is on the XJ??

**bmyohn** · 04-20-2007, 02:23 PM

bump, is it that black box by the rear shocks???

**bmyohn** · 04-20-2007, 07:40 PM

bump, any ideas guys

i may just take it to the mechanic tomorrow anyways

CherokeeXj · 04-20-2007, 07:56 PM

the charcoal canistor should be by the engine...i think i don't see why it would be in the rear

SS01XJ · 04-20-2007, 08:47 PM

On a 2001, it's in the rear, under the Jeep about half way between the rear drive shaft and the left frame rail. It's a little forward of the rear axle and bolted to the floor pan. It has a black cover.

**bmyohn** · 04-20-2007, 08:52 PM

thanks, so i should check all the hoses and stuff that connect to that black box?

SS01XJ · 04-20-2007, 09:40 PM

Quote:

Originally Posted by bmyohn

thanks, so i should check all the hoses and stuff that connect to that black box?

Check all the lines (hard & soft) from the gas tank to the canister and forward to the purge pump in the engine compartment.

**bmyohn** · 04-20-2007, 09:41 PM

just check for holes/loose lines and such??

SS01XJ · 04-21-2007, 11:21 AM

bmyohn, I responded to your thread when you asked about the location of the charcoal canister. You then asked about checking for leaks and such and I replied with some additional comments. My old brain just assumed that your problem was the usual one about leaks in the evaporative control system. Reading your original post this morning, I see that you state that your problem is electrical. You should be checking the wiring and plugs that go to the leak detection pump and the solenoid operated purge valve. They are both located under the hood near the firewall and passenger side of the engine compartment.

This might be hard to do without a schematic. Sorry if I misled you.............Stan

**bmyohn** · 04-22-2007, 08:00 PM

no problems Stan, my dad is gonna take it to a shop tomorrow, i looked around but couldnt really find the problem, so were gonna get a mechanic to look at it

thanks for ur help

Brendan

04-20-2007, 08:47 PM	#10
SS01XJ Registered User Join Date: Aug 2004 Location: NE OHIO Posts: 143 Profile Gallery Classifieds My Jeeps	On a 2001, it's in the rear, under the Jeep about half way between the rear drive shaft and the left frame rail. It's a little forward of the rear axle and bolted to the floor pan. It has a black cover.

04-21-2007, 11:21 AM	#14
SS01XJ Registered User Join Date: Aug 2004 Location: NE OHIO Posts: 143 Profile Gallery Classifieds My Jeeps	bmyohn, I responded to your thread when you asked about the location of the charcoal canister. You then asked about checking for leaks and such and I replied with some additional comments. My old brain just assumed that your problem was the usual one about leaks in the evaporative control system. Reading your original post this morning, I see that you state that your problem is electrical. You should be checking the wiring and plugs that go to the leak detection pump and the solenoid operated purge valve. They are both located under the hood near the firewall and passenger side of the engine compartment. This might be hard to do without a schematic. Sorry if I misled you.............Stan