Hi all,

So i've recently acquired a 1996 Grand Cherokee Limited Edition with 120,000kms. Absolutely love the truck but have a quick question that hopefully y'all can help me with.

When i bought it, the check engine light was on with the P0420: Catalyst System Efficiency Below Threshold. Also, there was a warning for the engine coolant sensor malfunctioning coming up on the display. When I looked up the code I found that it could be caused by an exhaust leak (which the truck had), an 02 sensor malfunction, or the coolant sensor malfunction. I cleared the code when I picked the truck up and it didnt come back on for the entire 50 minute trip home. I fixed the exhaust leak today but want to make sure that the exhaust leak was the probable cause. If it is the coolant sensor, where is it located and how can I check to see if it's working properly?

Thanks for reading,

Jesse J.

 

the "engine coolant sensor bad" pops up on almost all those grand cherokees i got the same one and it does it all the time, some people even replace it and it still comes up

 

My '97 ZJ FSM shows a coolant temp sensor below the cyl. #2 exhaust primary pipe, between & below two freeze plugs. Don't know if that's the one you need though. It doesn't tell how to test it. Sorry.

 

heres a write up on how to fix that "coolant sensor bad" warning

http://www.jeepforum.com/forum/f13/c.../#post11719192