2010 Expetion P0420 code.

[Seth Evans]

Hey guys, new to the forum. Recently bought a 2010 Expedition XLT/CCV that was an ex DOC vehicle. 100k miles, super clean well taken care of and not ragged out like alota the ex LE cars/trucks are. Anyhow, test drove it for about an hour, climbed under it looked around, got on the highway, stomped it etc etc. It missed and studdered at first when stomping it but once it got warm it wnet away. Pretty sure it had just been sitting for a bit and hadn't been ran. Left the dealer, stopped at the parts store and put a new airfilter on it. Few days later I get a check engine code and it comes up as a P0420 "Inefficient Catalyst Bank 1". Researched the code and found it could be anything from coils, plugs, injectors, leak in air intake, MAF, and the Cats. So I popped the air box top off, re adjusted everything and tightened the 2 clamps up in the airbox side and the throttle body side, code goes away and then comes back again. Adjusted again, went away, came back again. Anyone know of a common problem on these before I throw a bunch money into coils, plugs and injectors (although it wont hurt to do so) It will occasionally miss or studder if I really get into it (floor it or get close to it). In NC ya have to have your vehicle inspected before getting permanent tags and shelling out a few hundred bucks right after buying this thing is gonna hit the wallet hard. Any advice would be greatly appreciated.


Seth

 

[Big Brian]

this site is really helpful, can help you to understand things so you are not just throwing parts at it

http://easyautodiagnostics.com/

 

[Bedrck47]

The following was copied from the 2010 Service manual

P0420 - Catalyst System Efficiency Below Threshold (Bank 1)


Description: Indicates the bank 1 catalyst system efficiency is below the acceptable threshold.
Possible Causes: Use of leaded fuel
Damaged heated oxygen sensor (HO2S)
Out of range engine coolant temperature (ECT) sensor
High fuel pressure
Damaged exhaust manifold
Damaged catalytic converter
Oil contamination
Cylinder misfiring
Downstream HO2S wires incorrectly connected
Damaged exhaust system pipe
Damaged muffler/tailpipe assembly
Retarded spark timing
Leaking fuel injector

Diagnostic Aids: The signal line lengths of the downstream HO2Ss are compared against the signal line lengths of the upstream HO2Ss. Under normal closed loop fuel conditions, high efficiency catalysts have oxygen storage which reduces the frequency and amplitude of the downstream HO2S as compared with an upstream HO2S signal. As catalyst efficiency deteriorates, its ability to store oxygen declines and the downstream HO2S signal has an increased amplitude and frequency, approaching the amplitude and frequency of the upstream HO2S. Once beyond an acceptable limit the DTC is set.
Vehicles with universal HO2Ss compare the signal line length of the downstream HO2Ss to an expected signal line length of the downstream HO2Ss with a deteriorated catalytic converter.
Application Key On Engine Off Key On Engine Running Continuous Memory
All — — GO to Pinpoint Test HF .

Sending you a PM check the inbox

 

[Fred Valdez]

in my experience in dealing with p0420's...it's almost always the after cat sensor, drivers side... since you are talking about a stumble while driving and that you just got it, I would do a tuneup on it...new plugs, clean tb/maf. If after that you still get code and stumbles, probably the driver cat itself, it doesn't show itself until it gets nice and warm... tap on the cat with a wrench and see if you hear rattling....

 

[ExpeditionAndy]

Hey guys, new to the forum. Recently bought a 2010 Expedition XLT/CCV that was an ex DOC vehicle. 100k miles, super clean well taken care of and not ragged out like alota the ex LE cars/trucks are. Anyhow, test drove it for about an hour, climbed under it looked around, got on the highway, stomped it etc etc. It missed and studdered at first when stomping it but once it got warm it wnet away. Pretty sure it had just been sitting for a bit and hadn't been ran. Left the dealer, stopped at the parts store and put a new airfilter on it. Few days later I get a check engine code and it comes up as a P0420 "Inefficient Catalyst Bank 1". Researched the code and found it could be anything from coils, plugs, injectors, leak in air intake, MAF, and the Cats. So I popped the air box top off, re adjusted everything and tightened the 2 clamps up in the airbox side and the throttle body side, code goes away and then comes back again. Adjusted again, went away, came back again. Anyone know of a common problem on these before I throw a bunch money into coils, plugs and injectors (although it wont hurt to do so) It will occasionally miss or studder if I really get into it (floor it or get close to it). In NC ya have to have your vehicle inspected before getting permanent tags and shelling out a few hundred bucks right after buying this thing is gonna hit the wallet hard. Any advice would be greatly appreciated.


Seth

Welcome to the forum and congratulations on your new truck.

 

[ExpeditionAndy]

in my experience in dealing with p0420's...it's almost always the after cat sensor, drivers side... since you are talking about a stumble while driving and that you just got it, I would do a tuneup on it...new plugs, clean tb/maf. If after that you still get code and stumbles, probably the driver cat itself, it doesn't show itself until it gets nice and warm... tap on the cat with a wrench and see if you hear rattling....

Welcome to the Forum.

 

[Fred Valdez]

Welcome to the Forum.

Thank you sir...look forward to vast info to maintain my new to me sled

 

[ExpeditionAndy]

Thank you sir...look forward to vast info to maintain my new to me sled

There are a lot of guys on here that really know their stuff. I've found if you contribute and respond to questions when asked you'll get a lot of help.

 

[Seth Evans]

Thanks for the help guys, been a few days since I've been able to hop on here. I took the MAF off and cleaned it with some MAF cleaner thoroughly. Code went away and hasn't came back. Guess I didn't clean it well enough the first time. Still getting the miss and occasional shudder when I really get into the throttle (almost to the floor), but from past experience and as others have stated in replies, I'm gonna go ahead and do plugs and coils here soon.

Thanks, Seth