Jeep p0420 code

Many factors can cause the car computer to register DTC P0420 on Toyota or any car model. This makes it challenging to diagnose and fix the problem. Engine running rich or lean. Malfunctioning upstream or downstream oxygen sensor. Leaking fuel injectors. Lousy catalytic converter. Lousy engine coolant temp sensor.

Jeep p0420 code. P0420 Code. How to fix it. Don't spent tons of $$$. ~This also true for the po430 Code!Check out My Amazon Auto Accessories Store! Lets make that Weekend job...

Code P0420. Jump to Latest Follow ... West Virginia Jeep Club member ... i had some o2 sensor heater codes pop in my 04 cleared it out twice now, about 8k miles later, never returned, i think my jeep just fixes itself sometimes because it knows im too lazy to do it . 2004 Grand Cherokee Laredo 4.0

So I bought a used Jeep Patriot from a dealership in 2015 and it had about 80,000km on it already. I have since put another 80,000km on it. So I am about 160,000km. ... a P0420 code by itself is usually the cat. If you had a P0420 and another code like an O2 sensor performance code it may be the sensor, but in this case, I think you're looking ...The park, along with Peak Wilderness Protected Area and Knuckles Conservation Forest, make a World Heritage Site called The Central Highlands of Sri Lanka. To see the end of the wo...I have a 2012 jeep wrangler 2.6l i'm getting codes p0300 & p2308, srry Possible problems related to code p0171 P0441 patriot easy P0420 symptoms fixesPopular Engine Codes p0420 code p0172 code p00171 code p0128 code p0300 code p0456 code p0430 code p0442 code p0455 code p0113 code. ... Toyota 4Runner vs. Jeep Grand Cherokee | The Best Model Year For Every Budget 72 Car Safety Tips For Drivers Of All Ages & Stages DOWNLOAD THE APP. About. About FIXD; Editorial Process;Just bought a 2008 Jeep Patriot Limited. It is the first Jeep I have owned and am pretty happy with it. I bought it with 170,000km on it, and it has the check engine light registering code P0420 (catalytic converter issue). I am going to try two things: First, I am going to replace the O2 sensors. Second, I was thinking of trying to clean the ...

P0340 definition: Camshaft Position Sensor Circuit Malfunction. Issue Severity: SEVERE - Stop driving immediately. Repair Urgency: Fix this code immediately (same-day if possible) to avoid internal engine damage. Diagnosis: The vehicle may be difficult to start and the driver may also experience a lack of power when driving.For the past few weeks I was throwing a P0420 code for exhaust gas recirculation insufficent and was having a slight hesitation on acceleration. I replaced the egr, and cleaned the egr tubing.That did not work. ... Limo Tint All Around with Mopar Matte Black Front Window Decal) and Jeep Black Ops Paramedic Hood ...A code P0420 may mean that one or more of the following has happened: Leaded fuel was used where unleaded was called for (unlikely) A damaged or failed oxygen / O2 sensor. Downstream oxygen sensor (HO2S) wiring damaged or connected improperly. The engine coolant temperature sensor is not working properly.That P0420 codes is one of the most unambiguous of all the diagnostic trouble codes. That code is thrown when the upstream and downstream O2 sensors both have the same "switching frequency." That means that the cat is doing very little to change the exhaust gas composition. In other words, the cat needs to be replaced.Jeep Grand Cherokee & Commander Forums. ZJ Grand Cherokee Forum. Another P0420 CEL code Problem..... Jump to Latest Follow 1 - 14 of 14 Posts ...Jeep Patriot 2008 Engine Light - P0420 (code) Jump to Latest Follow 10K views 3 replies 3 participants last post by Terasec Sep 23, 2014. J. Jeepn_Creepn Discussion starter 5 posts · Joined 2014 Add to quote; Only show this user #1 · Sep 22, 2014. My engine lights keeps appearing and then dissapearing. ...

The Jeep 4.0-liter engine uses a cast iron block and cylinder head. It comes in both an inline-6 and inline-4 cylinder version and the specifications vary, depending on the vehicle...The P0420 code is a generic powertrain code that indicates a problem with the catalytic converter in a vehicle. Specifically for your Jeep Compass, it means that …A week ago I got a P0420 code, which is a catalyst efficiency below threshold. Can anyone help me pinpoint the issue? If it's just the O2 sensor I would be delighted, but I'm not so sure. ... A forum community dedicated to Jeep Wrangler owners and enthusiasts. Come join the discussion about reviews, performance, trail riding, gear, suspension ...Code P0420 means “Catalyst system efficiency below threshold (Bank 1).” Driving long-term with this code can cause engine and exhaust system damage. The most common cause of P0420 is a bad catalytic converter, but it can also be caused by other issues, such as a faulty oxygen sensor, a rich or lean running condition, or misfires.Diagnose a p0420 check engine code on a odb2 carCherokee 2001 2000 xj p0305 misfire engine code coil jeep dies testing misfires seconds ok later few start but rail I've got jeep v8 code p0505 came up engine run but sounds rough or missingP0420 tj wrangler.

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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 ...The P0420 code indicates that your vehicle's powertrain control module (PCM) monitors the poor efficiency of the catalytic converter at Bank 1. This code may also be triggered due to a bad catalyst or a false alarm caused by a faulty oxygen sensor at Bank 1. Basically, Bank 1 and Bank 2 are the two sides of the engine.The P0420 code signals a low catalyst system efficiency. This code suggests that the oxygen levels are below the desired threshold (Bank 1), which most often results from problems with your car ...NOTE: Take note that while the cods listed below are not strictly related to P0420 – “ Catalyst System Efficiency Below Threshold (Bank 1)”, these codes often appear with P0420. P0421 – “Warm Up Catalyst Efficiency Below Threshold (Bank 1)”. P0422 – “Main Catalyst Efficiency Below Threshold (Bank 1)”. P0423 – “Heated ...More Problems / code p0420. So to bring everyone up to speed in the last 2200 miles my motor was replaced, twice. Read about it here. Then after about another 1100 miles the water pump failed. On Oct 1st the check engine light came on. That was for the catalyst system, code p0420. Read about that here. I hoped that the O2 sensor just had a quirk.

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 .That code is a general code. If the converter is bad they will replace. If it's O2 sensor or because the converter fail because of another issue they will not replace under warranty.This page is meant to help you troubleshoot the Jeep Wrangler P0420 trouble code. It covers the P0420 code’s meaning, symptoms, causes, and possible …The Jeep power train control module (PCM)--or computer, as it is known in layman’s terms--controls the vehicle’s ignition, emission and fuel systems, along with other auxiliary sys...VEGASROBBI. 238 posts · Joined 2010. #3 · Nov 25, 2014. P0420,30 usually indicates a bad cat if not accompanied by any other codes or drivability issues. There are different types of cats, two way which handle HC and CO's and three ways which add NOx. There are aspirated cats and other odd configurations too.2D barcodes are being used in some interesting ways. Visit HowStuffWorks to learn everything about 2D barcodes. Advertisement In the summer of 1974 at a grocery store in Troy, Ohio...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 ...96XJ 4.0L Check Engine Code PO420. Check engine light came on, had it scanned at the dealership and the local auto hobby shop and came up with the same code, (PO420). The catylitic converter on there was a "Random Technology, Level-1" I had purchased from Quadratec and had installed some years back along with new (2) OEM O2 sensors at the time ...Jeep Platform Discussion. WK- Grand Cherokee (2005-2010) WK- Troubleshooting/Problems. P0420 and P0430. Jump to Latest Follow 3K views ... Hey everyone, getting these two codes on my 05 grand Cherokee 4.7L. Could possibly be both 02 sensors, a leak in the exhaust or a bad cat converter.I was getting repeated p0420 for cat efficiency below ok. And no other code. Cleared it and it would come back at a random time of next day to weeks. I suspected it may be as it has 450,000 km on original cats. Pricing for a new downpipe with cats was over $700 Canadian. 4.7l. 2004 So i monitored the o2 sensors, up and down stream with the ...Then set torque to display the O2 sensor outputs. You should then be able to see the levels cycling. Next step is to swap the offending sensors, (downstream usually), left/right & see if the fault stays on the one side, (bad cat), or swaps over, (bad sensor, much cheaper). I had this & it was a bad cat in the end.Code P0420 Jeep: Catalyst System Efficiency Bank 1. Hi guys, need some help for folks that have experienced this. Based on what I have looked up, it looks like a possible bad catalitic converter. I got a check engine light, I put my scanner on it and I erased the code. That cleared the check engine light.

2011 Jeep Compass P0420 Code. A few weeks ago my car started throwing a P0420 (Catalytic converter below threshold). I had the code cleared, it then came back on and proceeded to go back off on its own a week later. It returned a few days ago so now I am trying to figure out if this is a catalytic converter issue or an O2 sensor issue.

Jeep Cherokee P0420 Code Symptoms. The P0420 code in a Jeep Cherokee will often be thrown if one of your vehicle’s oxygen sensors is not functioning correctly. There are rarely drivability issues associated with P0420. For most people, the first sign that anything is wrong is the service engine soon light coming on.Hey all. So, im getting the 'ol P0420 and P0430 codes. Going to replace the CAT with a new DAVICO one, but how do I figure out what caused it to fail in the first place? Already replaced 3 out of 4 of the o2 sensors (Bank 1, #1 & 2 and Bank 2, #2) hoping that it would be just that, but it wasnt.How to diagnose code P0420 on a Jeep Patriot. 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 …02 WJ with P0420 code. So I've been doing some work to my WJ. I've got it down from 4 CEL codes to 1, the dreaded P0420. I went ahead and changed my catalytic converter with a brand new one but still have the code. I head that it could possible be related to the O2 sensors. I took some graphs of the voltages with the Torque Pro app.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...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.Code: P0420 Definition: Catalyst Efficiency (Bank 1) General Operation: The State of Change (SOC) catalyst monitor uses the signals from both the Upstream and Downstream Oxygen (O2) Sensors to detect aging of the catalyst. The Upstream O2 Sensor slow response monitor runs simultaneously to determine if the sensor signal is plausible. A pass/fail determination is made on the O2 Sensor slow ...Jeep Mechanic: Chong. Lots of times for the p0420 and p0430 , the o2 sensors are the culprit.Try these steps: check exhaust for any leaks. check the pcm software level , if out of date, update it. you will need to have it down at dealer . check o2 sensors connectors, for mositure or corrosion, or oil. replace o2 sensors, it's like the aging o2 ...

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P0420 Code. Hi, new to the forum and new Jeep owner. I've got a 2007 Grand Cherokee Limited with the 5.7. I had it checked out before I bought it and it showed a fault with a downstream O2 sensor which I replaced, the CEL was cleared, and I drove it 50 miles on the highway. Light stayed off for about a day.What It Is: The P0456 code in your Jeep Wrangler, identified using an OBDII scanner, indicates a small leak in the evaporative emission control system.It is often associated with codes like P0420, P0441, and P0440. Impact: P0456 typically doesn't pose an immediate threat to your Wrangler's driveability, but addressing any service engine soon light promptly is always wise.Even slight variations in the air/fuel mixture will cause the converter temperature to rise significantly. The "Catalytic Converter Efficiency" Diagnostic Trouble Codes (DTCs) P0420 and P0430, are among the top 10 DTCs technicians face. And while the description might imply a failed converter, odds are the ultimate fault lies somewhere else.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.Feb 4, 2024 · The P0420 code on a Chevy indicates the catalytic converter is not operating at maximum efficiency. A faulty oxygen sensor, a damaged catalytic converter, or an engine misfire can cause this. Getting the catalytic converter replaced by a mechanic is the common fix. Why Does My Jeep Wrangler Have a P0420 Code? P0420 Code!! Just changed out plugs and wires on the 3.8L. Had a misfire and found a bad wire after the tune up. I could smell unburned fuel coming out the pipe while troubleshooting that and now it's brought up the catalytic converter code P0420. I didn't run the thing for more than 10 min over the span of the weekend to find the ignition ...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.PLEASE HELP! Codes P0420 and P0420. Hi all! I am new to the forum. I have a 2011 GC Limited, V6, 3.7L, 160K Miles. A few months ago, the check engine light came on with the codes P0420 and P0430. Since then, I have replaced all 4 O2 sensors and the gas cap (I heard that may be an issue too).2011 Jeep Compass P0420 Code. A few weeks ago my car started throwing a P0420 (Catalytic converter below threshold). I had the code cleared, it then came back on and proceeded to go back off on its own a week later. It returned a few days ago so now I am trying to figure out if this is a catalytic converter issue or an O2 sensor issue.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 ...The Jeep runs fine really good actually. I don't care about looking at light just want it reliable . Save Share. Like. Sort by Oldest first Oldest first Newest first ... this will absolutely throw p0420 and related codes. I hope you are back up and running by now, if not i hope this helps! Black 2007 JKU Sahara, Rubicon Express 3.5" long arm ... ….

P0420 definition : Catalyst system efficiency below threshold (Bank 1) Issue Severity: MODERATE – Extended driving with this code can cause internal engine damage. Repair Urgency: Get this code fixed as …If code P0420 shows up on an OBD code reader, it means the engine's harmful gasses production has increased. That means the operational efficiency of the catalytic converter is below its threshold. The two oxygen sensors have measured its efficiency and deemed that it is low. That is why you see the P0420 code.The 2007 Jeep Wrangler uses a two-wire "Evaporative System Monitor" (ESM) switch. ... P0420 Code; P0430 Code; P0300 Code; P0455 Code; P0401 Code; P0172 Code; P0446 Code; P0011 Code; P0340 Code; Automotive Features toggle close features. Driving; Lifestyle; EVs and Hybrids; Trivia and History;VEGASROBBI. 238 posts · Joined 2010. #3 · Nov 25, 2014. P0420,30 usually indicates a bad cat if not accompanied by any other codes or drivability issues. There are different types of cats, two way which handle HC and CO's and three ways which add NOx. There are aspirated cats and other odd configurations too.Diagnosis. Jeep Gladiator P0420 Quick Info Table. Jeep Gladiator P0420 OBDII Code Defined. P0420 is generic (has the same meaning for all vehicles made in …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 …Code P0420 Nissan Description. The Engine Control Module ( ECM) monitors the switching frequency ratio of heated oxygen sensors 1 (front O2 sensor) and heated oxygen sensors 2 (rear O2 sensor). A three way catalyst converter (Manifold) with high oxygen storage capacity will indicate a low switching frequency of heated oxygen sensor 2.Jeep JK and JK Unlimited. If this is your first visit, ... Check engine light came on reading p0420 code. Does this code only get corrected by replacing catalytic converter? Tags: None. OhioYJ. in-famously viral. Join Date: Mar 2005; Posts: 15753; Share Tweet #2.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. Jeep p0420 code, If the voltage of the downstream oxygen sensor decreases, and begins to fluctuate like the upstream oxygen sensor, it means that the oxygen levels are too high and the Power Control Module will then store the P0420 trouble code and can be the source of the hard to start issue you’re experiencing., 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., 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., Jeep Grand Cherokee & Commander Forums. ZJ Grand Cherokee Forum. Another P0420 CEL code Problem..... Jump to Latest Follow 1 - 14 of 14 Posts ..., Jeep Grand Cherokee & Commander Forums. WJ Grand Cherokee Forum. P0420 trouble code. Jump to Latest Follow 1K views 1 ..., 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 ., We may earn a commission for products purchased through links on this page, CODE P0420 DODGE DART, CHRYSLER 200, JEEP CHEROKEE COMPASS RENEGADE. Code p0420 dodge dart, chrysler 200, jeep cherokee compass renegade Ff80 4ce3 afbc Jeep p0420 wrangler. 2004 jeep wrangler unlimited p0420 code. P0420 tj wrangler .. Check Details Check Details. I have a 2012 jeep wrangler 2.6l I'm getting codes p0300 & p2308, Srry. Check ..., P0420 Code 2007 3.8L JK. A couple of months ago the P0420 was thrown. I reset it with the BlueDevil OBD II tool. But after a series of trips it reappears. The catalytic converter had been replaced in 2017 and the vehicle only has about 5000 more miles on it since then. I replaced all four Oxygen sensors again to be sure but still the same problem., Dreaded P0420 Code -- after resolving misfire. Friends, I'm getting the P0420 code, Catalyst System Efficiency Below Threshold (Bank 1). Long story short, I drove several hundred miles with a misfire caused by a gunky fuel injector in cylinder 1 (codes: P0301, P0201). Hated to keep driving on it, but I was far from home when the misfire …, p0420のエンジンコードを自宅で修理できますか? p0420エンジンコードは自宅で確かに修理できます。ただし、問題があります。変更を進める前に、問題を正しく診断することが絶対に必要です。問題の原因に応じて、次のことが必要になる場合があります。, The P0420 code signals a low catalyst system efficiency. This code suggests that the oxygen levels are below the desired threshold (Bank 1), which most often results from problems with your car ... , 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 ..., Hello, I have a 2007 Jeep Patriot. My car currently had the check engine light one and I got it check and it said P0420, which i was told is very expensive to replace. ... but still lazy enough to cause a P0420. That code is just the computer saying that the downstream sensor is moving more than it should in comparison to the upstream sensor., Causes. A code P0430 may mean that one or more of the following has happened: The catalytic converter is no longer functioning properly. An oxygen sensor is not reading (functioning) properly. There is an exhaust leak. Possible Solutions. First, inspect for exhaust leaks., Went to a few other mechanics just for opinions and they agreed. We end up getting the cat conv. changed and 2 days later the CEL came back on, with the same P0420 code. Keep in mind, gas mileage is better and there's no more stuttering. The rpms even seem to be lower (they seemed a bit high, but idk if its related or not)., 2008 Jeep Wrangler codes p0430 and p0420. Need help diagnosing. Already replaced all 4 catalytic converters ..., If the voltage of the downstream oxygen sensor decreases, and begins to fluctuate like the upstream oxygen sensor, it means that the oxygen levels are too high and the Power Control Module will then store the P0420 trouble code and can be the source of the hard to start issue you’re experiencing., Codes P0420 and P0420. Hi all! I am new to the forum. I have a 2011 GC Limited, V6, 3.7L, 160K Miles. A few months ago, the check engine light came on with the codes P0420 and P0430. Since then, I have replaced all 4 O2 sensors and the gas cap (I heard that may be an issue too). I also stopped topping off when I get gas., It also could be that the engine coolant temperature sensor isn't working properly, but I think if that was the issue it would throw a separate code. Code P0420 is catalyst efficiency bank 1 (passenger side). You can check on-line how to test an O2 sensor. Good luck. Like., A suspect is wrong sensors. 3) check fuse #16 in PDC and relay oxygen downstream in PDC. a wag - INCORRECT O2 SENSORS, let us know. P0138-1/2 O2 SENSOR SHORTED TO VOLTAGE. P0420-1/1 CATALYTIC CONVERTER EFFICIENCY. P0141-1/2 O2 SENSOR HEATER FAILURE. P0161-2/2 O2 SENSOR HEATER FAILURE., 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., Even slight variations in the air/fuel mixture will cause the converter temperature to rise significantly. The "Catalytic Converter Efficiency" Diagnostic Trouble Codes (DTCs) P0420 and P0430, are among the top 10 DTCs technicians face. And while the description might imply a failed converter, odds are the ultimate fault lies somewhere else., I have a 2005 Jeep Grand Cherokee and I have codes P0420 and P2096. Submitted: 10 months ago. Category: Jeep. Show More. Show Less. Ask Your Own Jeep Question. Share this conversation. Answered in 2 minutes by: 6/6/2023., 2005 Jeep Liberty check engine light and P0420 code. 2005 Jeep Liberty check engine light and P0420 code. Analyzed by shop as catalytic converter being bad. Caused by engine burning oil; blue smoke from exhaust., 02 WJ with P0420 code. So I've been doing some work to my WJ. I've got it down from 4 CEL codes to 1, the dreaded P0420. I went ahead and changed my catalytic converter with a brand new one but still have the code. I head that it could possible be related to the O2 sensors. I took some graphs of the voltages with the Torque Pro app., =====Claim your FREE engine code eraser 👉 https://free.nonda.co 👈== How to Fix P0420 =====Engine Code P0420 Saving Repair Part..., The code P0420 (Catalyst Efficiency Issue) has nothing to do with you filling up the gas tank, its a coincidence it came up when you had just filled up. The most common causes of this are a failing o2 sensor, failing catalytic converter or an exhaust leak. This is an older thread, you may not receive a response, and could be reviving an old thread., Jeep Grand Cherokee & Commander Forums. WJ Grand Cherokee Forum. 04 WJ 4.7l P0420 Code. Jump to Latest Follow 1 - 5 of 5 Posts. B. BrianAzWJ · Registered. Joined Aug 3, 2021 · 12 Posts ..., P0420 Code. Hi, new to the forum and new Jeep owner. I've got a 2007 Grand Cherokee Limited with the 5.7. I had it checked out before I bought it and it showed a fault with a downstream O2 sensor which I replaced, the CEL was cleared, and I drove it 50 miles on the highway. Light stayed off for about a day., A code P0420 may mean that one or more of the following has happened: •Leaded fuel was used where unleaded was called for. •An oxygen sensor is not reading (functioning) properly. •The engine coolant temperature sensor. is not working properly. •Damaged or leaking exhaust manifold / catalytic converter / exhaust pipe., This page is meant to help you troubleshoot the Jeep Grand Cherokee 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. P0430 is usually caused by a catalytic converter issue or a bad O2 sensor. Table of, How to diagnose code P0420 on a Jeep Patriot. 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 …