p0420 code? - JeepForum.com
Sign Up   Today's Posts
User: Pass: Remember?
Advertise Here
Jeep Home Jeep Forum Jeep Classifieds Jeep Registry JeepSpace Jeep Reviews Jeep Gallery Jeep Clubs Jeep Groups Jeep Videos Jeep Events Jeep Articles
Go Back JeepForum.com > Models > Jeep Grand Cherokee & Commander Forums > ZJ Grand Cherokee Forum > p0420 code?

End of Summer Sale, 20% OFF!Introducing MONSTALINER™ UV Permanent DIY Roll On Bed LineRough Country Jeep Suspension Deals at Rockridge 4WD!

Unread 12-19-2012, 12:10 PM   #1
Registered User
1998 ZJ 
Join Date: Jun 2010
Location: , NY
Posts: 564
p0420 code?

Hey guys so this is the second time in about 3 months now that I had a check engine light code come up and have it be P0420. I looked it up in my haynes manual and all it says is catalyst efficiency below required level. Does this simply mean that my catalytic converter is on its way out?

ilive4cars0122 is offline   Reply With Quote
Unread 12-19-2012, 12:26 PM   #2
gs69350's Avatar
1998 ZJ 
Join Date: Aug 2012
Location: Sellersburg, IN
Posts: 323
That or one of the o2 sensors is reading incorrectly. If they are reading too close to the same reading it will trigger that code. Check cat for holes or rattles to make sure it is the cat.
1996 Jeep Cherokee Sport - "Smurple" 3.5" Lift, RE LCA's, 31's
1998 Jeep Cherokee Sport - 3.5" Skyjacker --GONE--
1996 Jeep Cherokee Government Edition - 3.5" BDS/Zone Lift --GONE--
1998 Jeep Grand Cherokee 5.9 Limited Platinum; 2" BB, 225/75/16 Wrangler MT/R --GONE--
http://www.facebook.com/groups/59limited/ <-- 5.9 Owner's group on FB.
gs69350 is offline   Reply With Quote
Unread 12-19-2012, 01:26 PM   #3
Registered User
1995 ZJ 
Join Date: Dec 2010
Location: Norman, OK
Posts: 2,006
Yes, your catalytic converter is basically not cleaning up the exhaust emissions to EPA standards. Simply put there may be nothing at wrong with it physically but the catalyst is degrading. I guess there is the very slight possibilty that the problem could be a sensor but to understand how the sensors read and what requirements are made to trigger the code that would be a far stretch.
jnicewan is offline   Reply With Quote

Jeep, Wrangler, Cherokee, Grand Cherokee, and other models are copyrighted and trademarked to Jeep/Chrysler Corporation. JeepForum.com is not in any way associated with Jeep or the Chrysler Corp.