No codes, but modules.

[Nukem]

2018 Rubicon JL. Started running rough yesterday afternoon. Check engine light comes on. Hook up reader and presents no codes. However, it tells me I have modules. $7E8 & 9. Could be O2 sensors, vacuum leak, or gas cap from what I googled. My question is, if I got no codes, is it more likely the gas cap than the sensors or a vacuum leak?

Sponsored

 

[oldcjguy]

If you have a check engine light you should have stored codes. 7E8 and 7E9 are just the addresses of your engine controller and transmission controller on the CAN network.

Gas cap and vacuum leaks will throw codes.

 

[Nukem]

If you have a check engine light you should have stored codes. 7E8 and 7E9 are just the addresses of your engine controller and transmission controller on the CAN network.

Gas cap and vacuum leaks will throw codes.

That's the thing the ODBC reader shows no codes. Just modules present.

 

[Barney392]

That's the thing the ODBC reader shows no codes. Just modules present.

Curious what code reader you are using. They are not all the same. I recommend JScan if you are using something different. Kind of sounds like you are looking in the wrong place for codes in your program.

https://jscan.net/

 

[Nukem]

Curious what code reader you are using. They are not all the same. I recommend JScan if you are using something different. Kind of sounds like you are looking in the wrong place for codes in your program.

https://jscan.net/

I have the Cen-Tech professional OBD2. Been reliable in the past.

 

[Barney392]

I have the Cen-Tech professional OBD2. Been reliable in the past.

I was checking for codes one day with my normal generic scanner and it showed no codes. Plugged in JScan and it gave me 6 codes. I only use JScan on the Jeep because of this.

 

[Nukem]

I was checking for codes one day with my normal generic scanner and it showed no codes. Plugged in JScan and it gave me 6 codes. I only use JScan on the Jeep because of this.

Interesting. Like I said, my scanner worked in the past. Let me see if any of my fellow jeepers here have one.

 

[Nukem]

okay. So i finally got a code: P0302. Nice. Misfire on cylinder 2. That's gonna be expensive on a 2018 JL. Not like the old days.

 

[dsgrey]

okay. So i finally got a code: P0302. Nice. Misfire on cylinder 2. That's gonna be expensive on a 2018 JL. Not like the old days.

Depends. Could be as simple as a rusted plug or as expensive as a cracked exhaust valve though the latter is very rare.

 

[tk1700]

Good luck. I assume 3.6? My 2019 3.6 started running rough on Wed. Had P0306, cyl 6 misfire. I looked at what I could without taking things apart and couldn't find anything wrong. Took it to the dealer Thur morning and coil, plug and injector are good. Waiting the results of leak down test and potential tear down. Its under the 5yr/60k powertrain warranty and I have an extended warranty so I should be covered there.

 

[oldcjguy]

okay. So i finally got a code: P0302. Nice. Misfire on cylinder 2. That's gonna be expensive on a 2018 JL. Not like the old days.

Do the usual... Check the plugs, swap the coil from # 2 to another cylinder and see if the misfire follows the coil. Try swapping the fuel injector to another cylinder and check the same thing, see if the misfire follows the injector.
Could also be the cam/rockers though. Seems to be an issue for some 3.6 motors. Pull the valve cover to check that. If you have to pull the intake to get to the plugs I'd pull the valve cover and check that first since you'll have it exposed.

Sponsored