P04000 code

As far as I know there is not an EGR valve on the 4.0 for that year. Looking in the service information that code is not even shown as a possible code. Parts listings does not show any EGR related items either.

I would erase the code and see what it does. It could be a ghost code or the reader isn't interpreting the information correctly.

I believe your vehicle has the ability to show codes on the dash using one of two methods. I have had some that do and some that do not. Do not use it very often when I have a scan tool.

You put the key in, push it in and turn the key on and off three times with the last time staying in the "on" position. (on-off-on-off-on) The dash should do a self test and the odometer will be dashes. Then it will display any codes in order.

Or

Put the key in, hold down the trip button and turn the key on. Dash should light up, odometer will read all ones the all 9s and finally display any codes.

Thank you Steve. Very helpful information. I tried to clear the code earlier with no luck. I will try the methods with the odometer to see if reader is spitting out wrong code. It does have an EGR solenoid. One vacuum hose goes toward engine and the other towards the rear of the vehicle near the gas tank.

That sounds like an EVAP vent solenoid.

EGR would be on the exhaust manifold or attached to the intake.
I looked at Mitchell, Alldata, Mopar, and Identifix and none of them show an EGR valve. And they also do not list P0400 as a valid code for the 4.0 liter six cylinder.

Looking at the emissions devices used it also does not show an EGR.

4.0L (242") SFI CCV, EVAP, TWC, FR, SPK, HO2S, CEC, MIL EVAP-LDP, EVAP-CPCS,
EVAP-VC, SPK-CC EGR testing process - None

Steve,

You are right! For some reason my Innova OBDII reader has a stuck code in it. I tried both of your suggested techniques and holding the trip reset and putting the key to on gave me the following:
5 of 5.1 and then 367322. Also in the one picture, the EGR solenoid is pictured. Probably nothing to do with original code from the obdII reader.

Karl

2005 Wrangler Unlimited 4.0l

Karl,

That solenoid is the EVAP purge solenoid. It opens to allow the engine to draw the fuel vapors stored in the charcoal canister into the intake to burn them. One end hooks to the intake manifold, the other goes to the charcoal canister.
Picture is a shiny new one.

Those numbers don't seem to match any of the codes that should be shown.
the 51 could be an O2 lean code.

Is your CEL on at this time? If it is hit one of the stores that will pull the codes for free and compare what they get with what you have.

It would not be the first time I have seen codes that do not fit the vehicle. Had a GM flex fuel in a couple years ago. It was telling me that the heated fuel separator was bad, Only problem is, those are only on diesels!

Steve,

Thanks for all of the help information. My DTC was not powered. Once I replaced the 10 amp fuse (26 in the engine compartment, my OBDII worked. Now it read P0431. It reads "warm up catalyst below threshold bank 2". I believe I had a loose catalytic converter before and tightened and it went away. I cannot be sure it was the same code. Any thoughts?

Karl

Yeah, no power will cause issues.
P0431 is one of those HMMM codes. It does not really tell you much that is useful. I have seen it be from air leaks in front of the catalytic converter, and many times it is a rear O2, that is just barely in spec.
Check it over and see what you find.