Hi Guys,

I recently picked up a 2000 Cherokee sport 4x4 w/ 4.0L auto. I drove it home 300mi & it ran great w/ 20 mpg. Last week I added some Seafoam to the tank & a few days later, it started running iradically rough. Today the check engine light came on & started flashing while I was driving, eventually staying on. I'm thinking I wound up contaminating the O2 sensors. I tried the key on/off 3x & no code on the OD & the engine light stays lit. How do I determine which sensor or if that's even the problem. I thought that the key method would give up the code, is it the year? Any advice is appretiated.

thanks,
scott

 

Can anyone help me out with the code situation?

 

They key trick does not work on the 2000 or 2001? You have to take it to a shop or parts store and have them read the code. There is no other way. Get the codes read then we can help.

 

Thanx Ken

That's prob why I wasn't getting anywhere I just ordered a code reader, so I'll see where that gets me & post my findings. Does my theory of the Seafoam breaking up junk in the system & screwing up the O2 sensors sound viable?

 

Yes. If the fuel system had never been cleaned itll break all kinds of stuff loose, I had a friend who did this to his Chevy and it toasteds the O2 sensors. Seafoam will also cause random misfires as well while its cleaning the system out.

 

Thanx Fish,

I'll let ya'll know when I get the code & post the results.

 

Not sure if this works on the 2000, but have you tried to disconncet the battery for a short while and see if the code goes away? Might be something cheap to try.

 

Started her up today & seemed to run fine. Disconnected the batt & touched the leads together, the check eng light is now off. (hopefully it was just the seafoam). We'll see if it's stays off.

Thanx for the advise all.