Jeep p0420 code

P0430 Jeep Code - Catalyst Efficiency Bank 2 - Code Popularity: 107,745 Views - Repair Importance Level: 2/3 - Repair Difficulty Level: 2/3. Table of contents. Created and updated by William Orellana on Aug 20, 2020. Possible Causes; Tech Notes;

Jeep p0420 code. Anyways ever since this cat has been new on the vehicle (2007 Pontiac Grand Prix GXP), I have been seeing the P0420 code nonstop. The shop stated that sometimes new cats can throw this code out. I have cleared it several times, the shop replaced that cat with another new one and I am still having the same issues. P0420 is the only code in the ...

October 03, 2023 -. P0420 stands for a code that signals the "Catalyst System Low Efficiency" issue and is a relatively common occurrence, especially with cars that are only driven over short distances. As the catalytic converter plays a vital role in reducing emissions and maintaining the overall performance of your vehicle, it is important to ...

A P0420 code is set when the upstream sensor and the downstream oxygen sensor sense the catalytic converter is not doing its job. Basically, the amount of oxygen going into the converter is not being burned, and it detects it through the downstream sensor. Oxygen is the key here. Modern Engine Management Systems leave a little bit of extra ...no the code P0420 mean the cat is done not going had it happen to my last car before i bought my jeep i would just do a cat from sumit racing the dynomax one is like 99.00. ... A forum community dedicated to all jeep owners and enthusiasts. Come join the discussion about performance, engine swaps, modifications, classifieds, troubleshooting ...Yes there is a technical service bullitin for 2005 Jeep Cherokee involving codes P0420 and P0430. However, if you read the SUBJECT line in the bulletin, you will see that this bulletin applies to the 4.7L engine - NOT the 3.7L engine, which you said your Jeep is equipped with. The ECU uses reading from upstream and downstream O2 sensors to ...Code P0430 means that the downstream oxygen sensor from the catalytic converter on bank 2 detects the cat isn’t operating to efficiency standards, based on factory specifications. The P0430 trouble code is considered generic, meaning it occurs on vehicles of any type and model. The P0430 shows a problem with the emissions system.ENSURE NO OTHER ENGINE CODES ARE PRESENT Plug the FIXD sensor (or another OBD scan tool) into your car's OBD-II port, and scan for any engine codes. If P0420 is your only code, you can continue with the proper diagnosis for this code. If other codes are present, they may need to be ad-dressed first.When left unattended, a P0456 Jeep code can lead to compounded performance issues and huge repair expenses. That said, it is best to pick up on its symptoms early on. P0456 Jeep code symptoms include: A triggered Check Engine Light. Starting difficulties. Fuel odors in your cabin.JEEP Wrangler CAT Off (P0420 , P0430) ..... Call 050 050 397 9117This page is meant to help you troubleshoot the Jeep Wrangler P0430 trouble code. It covers the P0430 code's meaning, symptoms, causes, and possible solutions. P0430 is an emissions-related trouble code and is virtually never a breakdown risk. ... The bank 1 version of this code is P0420. Jeep Wrangler P0430: Symptoms.

Jeep p0420 code help !!!! I've had a check engine light on since August- throwing the p0420 code for catalytic insufficiency. The car has been driving completely fine and the mechanic told me he wouldn't worry about it, just keep driving. The light turned back off for a while, then turned back on (same code).I own a 15’ patriot 4wd latitude , this is my wife’s daily driver we bought it off the dealer 4 years ago aprox, I’ve done maintenance throughout the years , now I had that p0420 code pop out. I’ve had it about for almost 2 years now , and it’s bothering me .Model Specific Jeep Discussions. Wrangler TJ (Model years 1997-2006) TJ Technical Discussion. p0420 code. Jump to Latest Follow 21 - 25 of 25 Posts. 1 2. DoubleOught · Registered. Joined Feb 21, 2014 · 1,209 Posts #21 · Jun 28, 2014. Only show this user. Also agree with you that every 99 4.0 I have seen also had the old style manifolds. ...2003 Grand Cherokee Laredo, 4.0L I6, SelecTrac, 191xxx miles I purchased it last November. That winter, I had a P0420 code pop up intermittently, but without any loss of fuel mileage or performance.CEL - Code P0420, 1.3k miles, 2015 EcoDiesel built in January. So my 2015 Jeep EcoDiesel threw a CEL on my way back from folks this afternoon, about a 45 minute drive. Hot as Hades here in Central Texas today. Threw the code 5 mins after startup. Ran the OBD-II scanner when I got home, saw it was P0420. Just bought the truck in June, it had ...

This page is meant to help you troubleshoot the Jeep Grand Cherokee P0420 trouble code. It covers the P0420 code's meaning, symptoms, causes, and possible solutions. P0420 is the most common OBDII code and is virtually never a breakdown risk. A failing oxygen sensor or bad catalytic converter are the most common causes of P0420.102 posts · Joined 2013. #1 · May 24, 2019. I have been dealing with a frustrating P0420 code. Maybe once a tank (for me that is like a little over a week or so). and then I have to be driving with low RPMs in the 2000-2500 with little if any throttle. It seams to be more likely at half a tank Or less. Engine is most often at full operating ...Code P0420. Jump to Latest Follow 13K views 5 replies 3 ... West Virginia Jeep Club memberThe PCM compares the switching frequency of the after cat O2 sensor with that of the before cat O2 sensor. If the frequencies match, then the cat is bad. That method of cat efficiency detection ensures that a bad O2 won't generate the P0420 code. O2 sensor failure will not create the matching frequencies. Replace the faulty catalytic converter.P0420 Code: Catalyst System Efficiency Below Threshold (Bank 1) - In The Garage with CarParts.com. Get 10% OFF EVERYTHING . In The Garage with …In this video, we tackle a P06DD diagnostic trouble code in a 2016 Jeep Wrangler with a 3.6L Pentastar engine. This code signifies an issue with the oil pres...

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Vídeo explicativo sobre el CÓDIGO DE FALLA P0420. Descubre qué significa, por qué ocurre y cómo solucionarlo correctamente.LEER SOLUCIÓN DEL CÓDIGO OBD2 EN...Been getting the p0420 code and if deleted it comes back in about 2 weeks so ---- I stop and get a gallon of laquer thinner and put it in the tank--- ... I talked to the Jeep mechanic changing the engine in my Jeep about the cats. The cats were giving off a fine residue which, due to the close proximity of the cats to the exhuast valves, the ...P0430 Code Diagnostic Help - 2012 Laredo 3.6. Hello all, I have a 2012 grand Cherokee, 146k miles, and recently had my check engine light come on. Ran the code and it came back with P0430 Low catalytic efficiency. Decided to buy a better scanner as I'm starting to do more and more of my own stuff and saved the attached reports.2009 3.7 V6 WK 133,000 miles. Unlikely that cleaning throttle body killed the Cat. Manually moving the throttle should produce no issues. Have someone put a scanner or oscilloscope on the front and rear O2 sensors to confirm the P0420. That person will look at the wave forms of each O2 sensor.When the P0420 code appears, the catalyst system efficiency is below the threshold for a particular engine bank, often referred to as Bank 1. This code is related to the vehicle's catalytic converter and oxygen sensors. The primary purpose of a catalytic converter is to reduce harmful emissions from the engine by converting toxic gasses, …Jeep Grand Cherokee & Commander Forums. WK Grand Cherokee & XK Commander Forum. code P0420? 1450 Views 0 Replies 1 Participant Last post by tednelson83, May 7, 2007. T. tednelson83 Discussion Starter · May 7, 2007. Only show this user. has anyone ever gotten this code? was there an easy fix OTHER than replacing the cat? ...

When a Jeep gets a P0430 code, it simply means that the catalytic converter is not able to function properly. The catalytic converter is one of the last components of an emission diagnostic system that all needs to work. How To Troubleshoot and Fix a Jeep P0430 Code .Code p0420. We replaced the all O2 sensors and it did great, no check engine light. Now it's back on, same code. Trying not to replace cat converter. Any ideas on what else it could be. I was told to change the spark plugs. The jeep runs fine, no weird sounds, motor sounds great, no noticeable leaks. 2007 wrangler JK.1 post · Joined 2019. #1 · Jan 18, 2019. 2010 Jeep Wrangler Unlimited Rubicon 3.8L. 280,032 miles. Code P0401 Problem. I installed my 2nd EGR Valve but I still get the code. I even Just replaced last night all 4 O2 sensors That I got from Jeep dealer parts department. Drove it 150 miles the only thing that comes up now is P0401 again.The P0420 code is also referred to as 'OBD II Code P0420 Bank 1'. P0420 is a common emissions fault code, and it indicates that the catalytic converter is not working properly. For the catalytic converter to work at its best, the emissions or feed gases that go into it must be perfectly balanced and not excessive. ... Jeep 3.6 Engine Problems ...Aug 20, 2020 · As the code description implies the P0420 code means that the vehicle's control module has detected that the three-way catalytic converter is not working properly (is not as efficient as the factory is expecting). Unfortunately, the P0420 is a fairly straight forward code, and a fairly common problem. This code points to a failing Catalytic Converter. The Oxygen Sensors measure the amount of emissions in the exhaust going into, and then out of the converter. When they see that the converter is not "cleaning" the exhaust enough to meet specs, …If you've been looking to learn how to code, we can help you get started. Here are 4.5 lessons on the basics and extra resources to keep you going. If you've been looking to learn ...Got the ol’ P0420 code recently in a 2006 2.4l. Jeep has new oxygen sensors (previous owner) so I did a few tests on the Cat. First, the OBD showed the second O2S sensor fluctuating between .300 & .700. Jeep was warmed up and rpm’s at 2,000. Also the exhaust temp exiting the cat was...In this video, you'll learn the causes and solutions of the P0420 code. The causes of the P0420 code are a bad catalytic converter, an ECM update, an exhaust...The most common symptom reported for the P0420 error code is an illuminated check engine light. You may also hear a loud exhaust noise with the P0420 …

Confirm it's a P0420 code. Before we move into the details on fixing the P0420 code command is very important to make sure that the problem exists in the 1st place. Therefore, the first step here is to use an OBDII tool scanner and connected it to the vehicle to check whether the P0420 code is there or not.

Jeep Wrangler P0420 Code Possible Solutions Often, the oxygen sensor is the cause of P0420. Specifically it'll usually be the O2 sensor(s) on the upstream side of the catalytic converter. But, don't be surprised if it's not. It would be a good idea to check the exhaust for leaks first.The P0420 code is set when the Catalyst monitor sees a decrease in voltage from the rear Monitoring Oxygen Sensor (s) and an increase in switching activity—from rich to lean to rich, etc.—that closely resembles the front Oxygen Sensor (s) during the time the computer is activating the Catalytic Converter monitor test.Code P0420:02 Sensor Upstream Replacement:2015 Jeep Patriot Sport FWD 2.0L 4 Cyl.Lubricant:Permatex Dielectric Tune-Up Greasea. Autozone Link - https://www.a...P0420. I just bought 2013 patriot latitude about a months ago. The dealer have changed the catalytic converter and a o2 sensor for me. Today on my short trip the engine light on. I went to autozone for them what's the code for and they said P0420. My question is how to fix this code when I just get catalytic converter and sensor replacement.P0430 Jeep Code - Catalyst Efficiency Bank 2 - Code Popularity: 107,745 Views - Repair Importance Level: 2/3 - Repair Difficulty Level: 2/3. Table of contents. Created and updated by William Orellana on Aug 20, 2020. Possible Causes; Tech Notes;83 posts · Joined 2007. #1 · Nov 22, 2007. The check engine light came on yesterday after driving from Tennessee to Michigan for the holiday. I stopped into to local auto parts store to have them pull the code. It said P0420 Catalyst Efficiency Below Threshold (Bank 1) I'm assuming that it's an O2 sensor downstream of the converter.A: The P0420 code is a diagnostic trouble code that indicates a problem with the efficiency of the catalytic converter in the vehicle’s exhaust system. Q: What are the symptoms of a P0420 code? A: Some common symptoms of a P0420 code include reduced engine performance, increased fuel consumption, and the illumination of the check …bush1355. 11 posts · Joined 2009. #3 · Jan 9, 2021. I have had this code P0420 catalyst efficiency for a few years now. Originally cobe was accompanied by 02 sensor code. (no P code to recall, but P code present) Have had only P0420 since. Dealer said new converter needed ($1300), but running fine in mileage & performance.

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This page is meant to help you troubleshoot the Jeep Grand Cherokee P0420 trouble code. It covers the P0420 code's meaning, symptoms, causes, and possible solutions. P0420 is the most common OBDII code and is virtually never a breakdown risk. A failing oxygen sensor or bad catalytic converter are the most common causes of P0420.P0133 Jeep Code - O2 Sensor Circuit Slow Response Bank 1 Sensor 1 - Code Popularity: 37,482 Views - Repair Importance Level: 2/3 - Repair Difficulty Level: 2/3. Table of contents. Created and updated by William Orellana on Jun 14, 2020. Possible Causes; Tech Notes; Description; How to Fix;P0430. had the Check Engine light on my 05 Grand Cherokee with the 4.7 V8 with 80k miles. Local trusted mechanic says all four O2 sensors are working and both catalysts generate at least 100 degrees via infrared thermometer. Tried to clean thinks up with SeaFoam and ChemTool products but the code would come back.in my case , 2011 patriot latitude, mil came on , dealership said o2 sensor , light went out after replaced. then back on 30 miles later, they said it was other o2 sensor. code p0420. came back on next day , said cathaletic convertor needed replaced. i doubted their word as less than 40k miles. and noticed they had greased threads on gas tank ...Mar 29, 2023 · B. bardwell02. 72 posts · Joined 2011. #2 · Mar 30, 2023. Hi; I have never had this code on my Jeep, but interestingly enough it's popped up on one of my other vehicles, an Audi RS4 (I believe it's P0430 - catalyst efficiency on that one!) Common cause on those cars is a bad O2 sensor, not the cat itself going bad. Jeep Wrangler P0420 Code Possible Solutions Often, the oxygen sensor is the cause of P0420. Specifically it'll usually be the O2 sensor(s) on the upstream side of the catalytic converter. But, don't be surprised if it's not. It would be a good idea to check the exhaust for leaks first.P0420 code indicates that signal from downstream sensor is similar to signal from upstream sensor and cat is not providing increased O2 content of exhaust stream as expected. P0138 is high voltage code from downstream O2 sensor, usually indicates that sensor isn't putting out normal varying voltage signal based on O2 content of exhaust stream ...How to diagnose code P0420 on a Jeep. Typically, you'll find out about P0420 because your malfunction indicator lamp or "check engine light" turned on & you or a mechanic diagnosed the problem with an OBD II code scanner like this one from Bluedriver. You may experience a very slight reduction in engine power from reduced exhaust flow, … ….

2813 posts · Joined 2010. #5 · Dec 6, 2010. 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.2008 Jeep Wrangler codes p0430 and p0420. Need help diagnosing. ... I have a 98 grand cherokee 4.0l with an P0420 code and an incomplete evap monitor test. The 420 code sometimes will stay off for a week after erasing and then come back. I checked for vacuum leaks mys ...This video will show you how to fix a seemingly fine catalytic converters (FOR OFF-ROAD ENVIRONMENTS ONLY) so that your check engine light turns off. The ben...Summary. DTC P0520 stands for "Engine Oil Pressure Sensor/Switch "A" Circuit.". This is logged when the PCM detects problems with the oil pressure sensor, oil pressure switch, or the oil pressure in general. Code P0520 is usually triggered because of faulty oil pressure sensors, bad circuitry, and low oil pressure.Sep 26, 2023 · HELP!! P0420, P0153 codes. I have a 2007 Wrangler, we replaced the complete exhaust system from the manifold back about 18 months ago and replaced all the O2 sensors, Recently my check engine light came on, upon checking with a code reader, code P0153 O2 sensor 2/1 Slow Response came on. I cleared the code, thinking it wasn't possible for the ... Matt Konkle. August 27, 2015. Tweet. Torque Staff Report. This method is used to retrieve OBD I and OBD II diagnostic trouble codes from your YJ, TJ, XJ, ZJ, and early WJ Jeep models. Insert the key into the ignition. Turn the ignition On-Off-On-Off-On within 5 seconds. Record the 2-digit DTC as displayed by the flashing MIL.Unfortunately, the P0420 is a fairly straight forward code, and a fairly common problem. This code points to a failing Catalytic Converter. The Oxygen Sensors measure the amount of emissions in the exhaust going into, and then out of the converter. When they see that the converter is not "cleaning" the exhaust enough to meet specs, …P2096 stands for "Post Catalyst Fuel Trim System Too Lean (Bank 1)". This code is set when your vehicle computer perceives a lean fuel-to-air mixture downstream of the catalytic converter. There are different possible causes for the code, but the most common one is a fuel delivery issue. Some common symptoms include rough idling, bad fuel ...In this video I replace the rear O2 sensor (bank 1) on a 2008 Jeep Grand Cherokee 3.7 V6. This vehicle has a trouble code P0420 stating the catalyst system e...Jeep Grand Cherokee & Commander Forums. ZJ Grand Cherokee Forum. Another P0420 CEL code Problem..... Jump to Latest Follow 1 - 14 of 14 Posts ... Jeep p0420 code, 2012 jeep compass 2.4 codes p0301, p0420, p060b, p0776, common causes? where to begin repair? - Answered by a verified Jeep Mechanic We use cookies to give you the best possible experience on our website., P0455. EVAP System Large Leak. P1000 - P1099 (Fuel and air metering and auxiliary emission control) P1001. Ignition Key Off Timer Performance Too Fast. P1002. Ignition Key Off Timer Performance Too Slow. P1004. Short Runner Valve Control Performance., Recently my jeep has been kicking a P0420 code "Catalyst System Efficency Below Threshold (Bank 1)". ... I still need to fine tune some exhaust adjustments but this took care of my P0420 code for a year. Fast forward to August 2018 and driving around town and bing, P0430 code. This is now bank 2., We've got an exclusive Square promo code for hardware. Use code PTMSquare for 20% off your first hardware purchase. For new customers only. Part-Time Money® Make extra money in you..., Code Number Code Description Related Codes; P0420: Catalyst System Efficiency Below Threshold (Bank 1) P0430 - Catalyst System Efficiency Below Threshold (Bank 2), P0420 is a diagnostic trouble code (DTC) for "Catalyst System Efficiency Below Threshold (Bank 1)". This can happen for multiple reasons and a mechanic needs to diagnose the specific cause for this code to be triggered in your situation. Our certified mobile mechanics can come to your home or office to perform the Check Engine Light diagnostic ... , Overall probably the biggest mistake vehicles owners make when they have a P0420 code is to simply replace an oxygen sensor (H02S). It is important to do proper diagnosis so you're not wasting money replacing parts unnecessarily ... Find answers to all your Jeep Patriot technical questions. Show Less . Full Forum Listing. Explore Our …, To confirm it is an O2 sensor, you need to get a scanner and watch the O2 sensors in real time. If the sensor after the cat is displaying basically the same info as the sensor before the cat, the cat is toast. If the sensor after the cat is showing nothing, as in no voltage, the sensor is bad. A good sensor after the cat should show some ..., 11. Location. So cal. i would try to change out the "gas cap".Sometimes the computer will give a reading due to less pressure in the system which in result Could cause a p0420 in theory thinking the 02 sensors are adjusting Accordingly., Jun 14, 2020 · Tech Notes. The P0440 code means that the control module has detected a leak in the Evaporative Emission (EVAP). Loose fuel tank filler cap is the most common cause that triggers the P0440 code. ⚠ Check if your Jeep have Safety Recalls. , Mar 23, 2014 · I have a 2007 that I bought last year and yesterday while driving back from Stone Mountain the Check Engine Light came on. When I checked the code it was P0430. The local AutoZone suggested replacing the passenger O2 just past the cat. I replaced it but have not reset the system yet. , Overall probably the biggest mistake vehicles owners make when they have a P0420 code is to simply replace an oxygen sensor (H02S). It is important to do proper diagnosis so you're not wasting money replacing parts unnecessarily ... Find answers to all your Jeep Patriot technical questions. Show Less . Full Forum Listing. Explore Our …, trouble codes P0420 & P0432. I have an 04 wrangler with 4.0 (6 cyl) I took it to my mechanic and had them check it out. They told me that the computer gave trouble codes P0420 and P0432- insufficient flow through catalyst. They said that the O2 sensors seemed to be switching correctly and that they didn't seem to be mirroring each other., 14. Reaction score. 7. My 2005 Liberty 2.4L has started throwing the P0420 code. Runs fine. It will only do it when I ride about 30-45 minutes. Short trips out won't come on. I can clear the code and it will stay off until I drive 30-45 minutes. I had replaced the front O2 sensor when I first got the Jeep because of another code., Overall probably the biggest mistake vehicles owners make when they have a P0420 code is to simply replace an oxygen sensor (H02S). It is important to do proper diagnosis so you're not wasting money replacing parts unnecessarily ... Find answers to all your Jeep Patriot technical questions. Show Less . Full Forum Listing. Explore Our …, However, bypassing oxygen sensors may be illegal depending on where you live and you will end up with a check engine light or performance issues unless you reprogram the engine control module for the removal of the oxygen sensor. Bypassing the downstream oxygen sensor is the most common way to get rid of the P0420 code., P0420 Catalytic converter efficiency bank one. 2012 Jeep Patriot latitude 4x4 2.4L. So I was doing some research on this code and came across a recall for 2012-2017 Patriots. I've never received any recall notice in regards to this and it isn't showing up as a recall., Honda. In Honda vehicles, the P0420 code is not uncommon. Common culprits include deteriorating catalytic converters and oxygen sensors. Regular maintenance and prompt repairs can help resolve the issue efficiently. Ford. Ford vehicles may also experience the P0420 code. Exhaust leaks, failing catalytic converters, and …, =====Claim your FREE engine code eraser 👉 https://free.nonda.co 👈=====Engine Code P0420 Saving Repair Parts:C..., Jeep Wrangler P0420 Code Possible Solutions Often, the oxygen sensor is the cause of P0420. Specifically it’ll usually be the O2 sensor(s) on the upstream side of the catalytic converter. But, don’t be surprised if it’s not. It would be a good idea to check the exhaust for leaks first., On the month July this year, check engine light for code 0420 came to my car for the first time. After some detailed diagnosis, I changed the catalyst converter of my car. The very next day the check engine light popped up again and I changed the downstream O2 sensor too., 2007 Jeep Liberty 3.7 code p0420 catalyst efficiency bank 1. Most the most common cause for the code? Answered in 1 minute by: Jeep Mechanic: Pete. Hi my name is ***** ***** I will be happy to assist with this today.In some cases I may need more info to assist better.I apologize for any delay. The most common cause is a restriction in the ..., Causes. Diagnosis. Jeep Grand Cherokee P0420 Quick Info Table. Jeep Grand Cherokee P0420 OBDII Code Defined. P0420 is generic (has the same meaning …, Developing apps normally needs experienced programmers who are familiar with development. However, these low-code and no-code apps change the paradigm. Receive Stories from @elinex..., I'm getting a P0420 code on my 2009 Wrangler. This code is for "catalyst system below threshold bank 1". Is the driver side or passenger side bank 1? Is this a common code on these jeeps? If so, is it usually the catalytic converter or something else like a cracked exhaust manifold or bad oxygen sensor? Thanks, These codes illustrate two different sides of the engine. Engines with an inline configuration can contain just one bank. The P0430 code basically means the same thing as P0420 on the other bank, and therefore you can check out my guide about the P0420 code, which is much more detailed. RELATED: Bank 1 vs Bank 2 - Sensor 1 & 2, P0420 is a diagnostic trouble code (DTC) for "Catalyst System Efficiency Below Threshold (Bank 1)". This can happen for multiple reasons and a mechanic needs to diagnose the specific cause for this code to be triggered in your situation. Our certified mobile mechanics can come to your home or office to perform the Check Engine Light diagnostic ..., The code P0420 - Catalyst Efficiency Below Threshold (Bank 1) means that there is a problem with the catalytic converter of the Bank 1. The code P0430 means the same fault for the Bank 2 catalytic converter in an engine with two cylinder banks (e.g., V6 or V8). The catalytic converter or "cat" is a key component of the vehicle emission control ..., This vehicle has a trouble code P0420 stating the catalyst system efficiency is below threshold (bank 1). Maybe it's a bad cat or maybe it's a bad rear O2 sensor. Either way, I …, The most common fix for P0420 in the Jeep Renegade is a new catalytic converter, followed by an O2 sensor replacement. Before taking your Renegade into an exhaust shop for an (expensive) new catalytic converter, let’s ensure that’s what you need. Here’s a good P0420 diagnostic order for the Jeep Renegade: 1. Check for Other Codes., Here is a tutorial on how to fix code p0420 catalyst system efficiency below threshold bank 1 how to diagnose and fix a Catalytic Converter and what to look ..., JK 2009 - P0420 & P0430. ... These codes are commonly caused by cracked exhaust manifolds. This is a common problem on the 3.8L engine. ... A forum community dedicated to Jeep Wrangler owners and enthusiasts. Come join the discussion about reviews, performance, trail riding, gear, suspension, tires, classifieds, troubleshooting, maintenance ..., P0420. I just bought 2013 patriot latitude about a months ago. The dealer have changed the catalytic converter and a o2 sensor for me. Today on my short trip the engine light on. I went to autozone for them what's the code for and they said P0420. My question is how to fix this code when I just get catalytic converter and sensor replacement.