Go Back   Jeep Garage - Jeep Forum > Jeep Platform Discussion > Grand Cherokee - WJ > Troubleshooting/Problems

Join Jeep Garage Today
Reply
 
Thread Tools Display Modes
 
  #1  
Old 12-06-2010, 11:09 AM
Member
My Jeep: 2002 4.7 HO WJ
 
Join Date: Oct 2010
Posts: 17
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 1497
rojpon74 is on a distinguished road
P0420 Code?

Hi Everyone,

My 2002 WJ Overland with 4.7L HO engine has the California/50-State emissions system (4 oxygen sensors, 2 mini catalytic converters before the main convertor, no oxygen sensor after the main converter).

I'm getting a P0420 DTC, which according to the service manual and wjjeeps.com translates to "Catalyst System Efficiency Below Threshold (Bank 1)".

Question: which catalytic converter is this referring to? I'm assuming it's one of the mini converters since it refers to "Bank 1".

Thanks everyone for your help!
__________________

__________________
Rojohn Soriano
- 2002 Jeep Grand Cherokee Overland
- 2007 Dodge Grand Caravan SXT
- 1972 Dodge Challenger
Reply With Quote
  #2  
Old 12-06-2010, 01:56 PM
Frango100's Avatar
Premium Member

My Jeep: 2004 4.7L WJ
 
Join Date: Dec 2009
Location: Brazil
Posts: 5,050
Thanks: 9
Thanked 102 Times in 95 Posts
Rep Power: 526035
Frango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond repute
Re: P0420 Code?

I'm not an expert on O2 sensors, but because the PCM is looking to the O2 level before and after the mini converter, it can only see the performance of that particular mini converter. How you can ever know if the main converter is working ok, i have no idea.
__________________

__________________
Frank

JEEP Grand Cherokee 4.7 Lmtd 2004
HID 8000K in low and fog / Quad Squad member
KYB Gas-a-Just shocks / Pirelli Scorpion ATR 245/65/17 - Transgo reprogramming shiftkit.

VW Beetle 2.0 TSI 2013
My new toy
Reply With Quote
  #3  
Old 12-06-2010, 02:59 PM
2005JGC's Avatar
Senior Member


My Jeep: 2005 4.7L WK
 
Join Date: Nov 2010
Location: Portland, OR
Posts: 2,751
Thanks: 51
Thanked 69 Times in 58 Posts
Rep Power: 1653005
2005JGC has a reputation beyond repute2005JGC has a reputation beyond repute2005JGC has a reputation beyond repute2005JGC has a reputation beyond repute2005JGC has a reputation beyond repute2005JGC has a reputation beyond repute2005JGC has a reputation beyond repute2005JGC has a reputation beyond repute2005JGC has a reputation beyond repute2005JGC has a reputation beyond repute2005JGC has a reputation beyond repute
Re: P0420 Code?

bank 1 is whatever side of the engine the #1 cylinder is on... on the 4.7 its on the drivers side.

possible causes:

INTERMITTENT CONDITION
VISUALLY INSPECT CATALYTIC CONVERTER
EXHAUST LEAK
ENGINE MECHANICAL PROBLEM
UPSTREAM O2 SENSOR OLDER THAN DOWNSTREAM O2 SENSOR
CATALYTIC CONVERTER

__________________
Reply With Quote
  #4  
Old 12-06-2010, 03:45 PM
Member
My Jeep: 2002 4.7 HO WJ
 
Join Date: Oct 2010
Posts: 17
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 1497
rojpon74 is on a distinguished road
Re: P0420 Code?

Thanks. What would be the symptoms of an exhaust leak? I just had the heads rebuilit a month ago and they had to pull the exhaust manifolds as part of the removal/installation process. I also got a P0155 code a week ago...seemed to be an anomoly since it hasn't come back after I erased it with my code scanner.

Quote:
Originally Posted by 2005JGC View Post
bank 1 is whatever side of the engine the #1 cylinder is on... on the 4.7 its on the drivers side.

possible causes:

INTERMITTENT CONDITION
VISUALLY INSPECT CATALYTIC CONVERTER
EXHAUST LEAK
ENGINE MECHANICAL PROBLEM
UPSTREAM O2 SENSOR OLDER THAN DOWNSTREAM O2 SENSOR

CATALYTIC CONVERTER

__________________
Rojohn Soriano
- 2002 Jeep Grand Cherokee Overland
- 2007 Dodge Grand Caravan SXT
- 1972 Dodge Challenger
Reply With Quote
  #5  
Old 12-06-2010, 04:55 PM
2005JGC's Avatar
Senior Member


My Jeep: 2005 4.7L WK
 
Join Date: Nov 2010
Location: Portland, OR
Posts: 2,751
Thanks: 51
Thanked 69 Times in 58 Posts
Rep Power: 1653005
2005JGC has a reputation beyond repute2005JGC has a reputation beyond repute2005JGC has a reputation beyond repute2005JGC has a reputation beyond repute2005JGC has a reputation beyond repute2005JGC has a reputation beyond repute2005JGC has a reputation beyond repute2005JGC has a reputation beyond repute2005JGC has a reputation beyond repute2005JGC has a reputation beyond repute2005JGC has a reputation beyond repute
Re: P0420 Code?

P0155 is an O2 sensor heater fault code... but its a 2/1 code (bank 2 upstream) so more than likely not related to your current P0420 code.

4.7's regularly break exhaust studs (the back 2) and you would know by a ticking noise while the vehicle is running. Sometimes worse when its cold, if it gets really bad it will be all the time. if you have had a leak for a while you can see soot buildup around the leak.

Why was the head rebuilt? misfires will quickly meltdown a cat (why the mil flashes), foreign material getting into the exhaust can kill it too.
__________________
Reply With Quote
  #6  
Old 12-06-2010, 10:03 PM
Member
My Jeep: 2002 4.7 HO WJ
 
Join Date: Oct 2010
Posts: 17
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 1497
rojpon74 is on a distinguished road
Re: P0420 Code?

Thanks very much for the information. I'll take a look at the exhaust manifold and studs.

Heads were rebuilt due to warped heads and a couple of burned valves. Problems were centered on the right hand (passenger side) head but did the left side too for good measure. The engine had close to 200k miles when the heads were rebuilt.

Quote:
Originally Posted by 2005JGC View Post
P0155 is an O2 sensor heater fault code... but its a 2/1 code (bank 2 upstream) so more than likely not related to your current P0420 code.

4.7's regularly break exhaust studs (the back 2) and you would know by a ticking noise while the vehicle is running. Sometimes worse when its cold, if it gets really bad it will be all the time. if you have had a leak for a while you can see soot buildup around the leak.

Why was the head rebuilt? misfires will quickly meltdown a cat (why the mil flashes), foreign material getting into the exhaust can kill it too.
__________________
Rojohn Soriano
- 2002 Jeep Grand Cherokee Overland
- 2007 Dodge Grand Caravan SXT
- 1972 Dodge Challenger
Reply With Quote
  #7  
Old 12-06-2010, 11:11 PM
2005JGC's Avatar
Senior Member


My Jeep: 2005 4.7L WK
 
Join Date: Nov 2010
Location: Portland, OR
Posts: 2,751
Thanks: 51
Thanked 69 Times in 58 Posts
Rep Power: 1653005
2005JGC has a reputation beyond repute2005JGC has a reputation beyond repute2005JGC has a reputation beyond repute2005JGC has a reputation beyond repute2005JGC has a reputation beyond repute2005JGC has a reputation beyond repute2005JGC has a reputation beyond repute2005JGC has a reputation beyond repute2005JGC has a reputation beyond repute2005JGC has a reputation beyond repute2005JGC has a reputation beyond repute
Re: P0420 Code?

btw a broken stud is VERY easy to locate... the studs that mount to the heat shield are what break, so just get your fingers on the back of the heat shield and try (gently) to pull it away from the head, you will know if its broken because it will move... otherwise its solidly mounted and should not budge.
__________________

__________________
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Code Robert Palmer Trouble Shooting/Problems/Service 14 05-17-2010 11:48 PM
P0420 on an 01 WJ with 85K miles, help? dhillon09 Troubleshooting/Problems 4 04-10-2010 11:36 AM
P0420 trouble code Hamze Troubleshooting/Problems Discussion 5 03-29-2010 03:25 PM
p1391 code am2owens Troubleshooting/Problems Discussion 3 03-03-2010 12:34 AM
The Cause of My P0868 Code Robert Palmer Grand Cherokee - WK 10 09-29-2009 08:15 PM

Powered by vBadvanced CMPS v3.2.3

All times are GMT -5. The time now is 09:58 AM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Copyright 2012 - JeepGarage.Org
The Jeep Grand Cherokee Owners Community

JeepGarage.org is in no way associated with or endorsed by Chrysler Group LLC.