Last reported case: 6 years ago
Based on 3 owner reports, 3 from forums)
What is P0420?
P0420 indicates your catalytic converter is not cleaning exhaust gases effectively, typically triggered by a failing converter or upstream engine issues. This powertrain code is moderately serious and can affect emissions and performance, with Honda vehicles like the Accord and CR-V appearing most frequently in reports. Based on 975 repair cases, the average repair cost is $3847, ranging from $0 to $4700.
Common Causes:
- Failing catalytic converter (most common cause based on code definition)
- Upstream oxygen sensor malfunction
- Exhaust leaks before the catalytic converter
- Engine misfires or rich/lean fuel mixture affecting converter efficiency
Symptoms:
- Check Engine Light illuminated (primary symptom)
- Reduced fuel economy reported by some owners
- Possible lack of power during acceleration
- No noticeable symptoms in some cases beyond the warning light
🚗P0420 on 2010 FORD Expedition
This page focuses specifically on P0420 issues reported by 2010 FORD Expedition owners. The experiences and fixes below are from real owners of this exact vehicle.
Parts Often Involved:
What Owners Say
Real experiences from 2010 FORD Expedition owners
“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".”View original
“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.”View original
“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.”View original
“I just passed emissions a month prior so I don't have to worry about that. I know this is a generic code and there could be a variety of things causing it but since I have a bunch of new parts where would you start troubleshooting?”View original
“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.”View original
“Driving home today and my truck threw code P0420. It's a 2000 EB 4x4. 161k miles.”View original
These are real experiences shared by 2010 FORD Expedition owners on automotive forums and communities. Results may vary based on vehicle condition and repair quality.
About This Data
This page aggregates 3 discussions about P0420 from 2010 FORD Expedition owners across automotive communities.
Success rate (0%) is calculated from posts where owners confirmed whether their fix resolved the issue.
Last updated: 11/22/2019