How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask sprinkles08 Your Own Question
sprinkles08
sprinkles08, ASE Certified Technician
Category: Jeep
Satisfied Customers: 22807
Experience:  Chrysler/Dodge/Jeep Master Certified, ASE Master and Advanced Certified, Trans and Hybrid Specialist
9825021
Type Your Jeep Question Here...
sprinkles08 is online now
A new question is answered every 9 seconds

QUESTION}

Customer Question

QUESTION}
Submitted: 9 months ago.
Category: Jeep
Customer: replied 9 months ago.
I also added a can of sea foam to a new tank of gas to hopefully loosen any deposits it may have
Expert:  david craig replied 9 months ago.

Hi Im David thanks for visiting the site. do a back pressure test to see if your cats are clogged.

Expert:  david craig replied 9 months ago.

checking in to see how its going

Expert:  david craig replied 9 months ago.

do you still need assistance?

Expert:  david craig replied 9 months ago.

hello?????????

Expert:  sprinkles08 replied 9 months ago.

Hello and welcome to JustAnswer!

P0420 is an efficiency failure of the catalytic converter and an be caused by a few things.

It could be an exhaust leak before the converter which is drawing air into the exhaust stream through venturi effect.

It could be a lazy upstream oxygen sensor. If the sensor is aged or the downstream sensor was replaced leaving an aged upstream in place then it can set a converter efficiency code.

The most likely cause would be the converter itself.