Jeep p0420 code

El código P0420 se refiere a un problema con el sistema de control de emisiones de tu vehículo, específicamente al convertidor catalítico. Este componente es crucial para reducir las emisiones dañinas de escape y garantizar que tu automóvil cumpla con los estándares de emisiones. Cuando se activa el P0420, generalmente indica que el ...

Jeep p0420 code. 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.

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 …

The Kia Code P0420 refers to a diagnostic trouble code that indicates a problem with the catalytic converter in a Kia vehicle. The code specifically points to a catalytic converter efficiency below the accepted threshold, indicating that the converter is not effectively reducing harmful emissions. Understanding the Kia Code P0420 and its ...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 …Google Authenticator can now sync single-use two-factor authentication codes to Google Accounts, for added convenience. Google Authenticator just got an update that should make it ...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.Sep 1, 2023 8:12 PM EDT. Catalytic converter. Kim2480 via Wikimedia Commons (CC BY-SA 3.0) Check Engine Light Codes P0420 and P0430. Replacing a catalytic converter or "cat" has become a big, expensive drain on a lot of people's budgets these days. I want to share some information about what's happening here with emissions testing and some ways ...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.

Diagnostic trouble code (DTC) P0420 stands for “P0420 Catalyst System Efficiency Below Threshold (Bank 1).” It indicates that the exhaust system’s oxygen levels are below the required threshold in Bank 1, which can damage the engine’s exhaust and fuel system.P0420 OBD-II Trouble Code: P0420 Catalyst System Efficiency Below Threshold (Bank 1) P0305 OBD-II Trouble Code: P0305 Cylinder 5 Five Misfire Detected ... Jeep Wagoneer Forum 3K+ members. Home. Forums. Model Specific Jeep Discussions. Wrangler TJ (Model years 1997-2006) ...Since you don't have a cat the PCM will always think its not working and throw a code. There are devices you can buy to plug in where the O2 sensor was to trick the computer in thinking the cat is working, but I have never used on.If you’re a car owner, there’s a good chance that at some point you’ve encountered the dreaded check engine light. Code P0420 is a generic diagnostic trouble code that indicates an...I have a 2001 wrangler with about 175K. My CEL came on yesterday and I'm getting a P0420 code "catalyst system efficiency below threshold." In the last year or so, I've had intermittent problems starting it on cold mornings -- basically need to give it gas while turning the ignition and then keep my foot on the gas to idle for a while or it will stall.

My Jeep has about 114K miles on it. About 6 months ago, it set a code P0420. I replaced all four O2 sensors, but this did not fix the issue. Recently, I replaced the spark plugs and PCV Valve. The plugs that came out of the #4 cylinder looked very dark and had carbon on them. The rest of the plugs looked white to slightly tan with lightly worn ...FOLLOW THIS GUIDE if you have a P0420 code. I will explain what the code means, how to diagnose it, and all that backed up by 100+ fixes case study, where I. ... 2012 Jeep Compass Limited 2.4L: MIL disappeared by itself: 2016 Honda Accord EX-L 2.4L: O2 sensor short circuit: 2002 Subaru Legacy L 2.5L: O2 sensors: 1999 Honda CR-V EX 2.0L:Jeep Liberty P0420 Code Symptoms. The P0420 code in a Jeep Liberty 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.END OF SPECIAL NOTES. OBD II fault code P0420 is a generic trouble code that is defined as, P0420 - "Catalytic converter system, Bank 1 - Efficiency Below Threshold", and is set when the PCM (Powertrain Control Module) detects that the efficiency of the catalytic converter on Bank 1 has fallen below a minimum allowable threshold.2011 Jeep Grand Cherokee P0420 Pentastar v6. Jump to Latest Follow ... SUMMARY: I am testing to see if my P0430 code is the result of high levels of oil consumption by my Pentastar motor. I picked up a 0430 code in Dec of 2021. So I looked it up, says bank2 sensor2 below threshold and so on...

Glory supermarket east 8 mile.

Here’s a new one to add to the never ending list of what throws code p0339 on my 12’ jku sahara with 180,000 miles.. for about two weeks now after every time I fill up with gas my check engine light and traction control light comes on after I start hitting bumps or slightly rough spots in street. After hitting a rough patch the Jeep drags ...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.I really wanna become a diagnostics master, so any and all help is very much appreciated. I replaced the fuel pump ($300) in my WJ last year, and it ended up being the ECU which prompted me to stop being a parts cannon master. I checked the FAQ which listed all OBD2 codes and searched the forum for live data info but couldn't find anything.The jeep had 187,000 when they recalled the converter and I never had any trouble with it. Now, I have 205,000 and nothing but issues. Its a 4x4 and most of it has been replaced.

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 Jeep Wrangler is a car that bills itself on its fearless character. Jeep has sought to portray the car as the ultimate vehicle for adventure seekers who love exploring the unch... P0420 Code. My wife's 2015 2.4 4x4 threw a P0420 code which seems to indicate either a bad cat or bad o2 sensor. I was going to throw some sensors at it ($16 on RockAuto) but then I realized the federal emissions warranty on the cat is 80k 8 years and we bought it May 2015 and have 74k on it. So we are right on the tail end of the warranty ... The P0420 is a diagnostic trouble code mainly for Catalytic System Efficiency Below Threshold (Bank1). This code is stored in memory when the ECM would have detected a low efficiency in the catalytic system. The ECM determines the cat con's working efficiency with two sensors. As such, the Catalytic System Efficiency (CSE) metric regulates ...Jan 25, 2024 · Understanding the P0420 Code in Your Jeep Liberty. The P0420 code is a common diagnostic trouble code that indicates a problem with the catalytic converter in your Jeep Liberty. In this section, we will explain what the code means and its potential causes. Possible Causes for a P0420 Code in a Jeep Liberty. There are several factors that can ... 2014- 3.6L just got p0520 and P06DE. My pressure reads 100 psi and doesn't move. I was going to replace oil pressure switch but a friend said I probably need a new oil pump. I bought it used with 38 k on it and it now has 61k on it. Regular oil changes with Castrol Edge synthetic. Any thoughts would be appreciated.Jeep P0420 OBD II Trouble Code. The Jeep Grand Cherokee, Wrangler, Compass, and Renegade will likely show P0420 trouble codes. Upstream oxygen sensor failures are the root cause in many cases. However, exhaust leaks near the catalytic converter are common and can create false sensor readings. Replacing damaged sensors and sealing leaks are the ...The maximum weight a Jeep Cherokee can tow is 2,000 pounds. If a Jeep Cherokee is modified with a trailer tow package, it can tow up to 4,500 pounds. The Latitude, Limited and Trai...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.P0420 questionP1729 code P0420 jeep patriotCode p0420 dodge dart, chrysler 200, jeep cherokee compass renegade, ram promaster city fiat. How to Fix JEEP P0404 Engine Code in 3 Minutes [2 DIY Methods / Only $4.37] - YouTube

P0420 & P0430 codes - white smoke exhaust. I've been meaning to post about this for a few months now.. I bought this vehicle last summer and have put about 13k km on it. Shortly after I bought it the check engine light came on and it gave me codes P4020 & P4030 (catalytic converter is not performing as efficiently as it should be).

Curious how to create a website with HTML and CSS? You're in the right place! This step-by-step tutorial teaches you to code your own website from scratch. Learn to Build a Website...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...Jeep Cable Ties Plastic Tool Wire Puller 10mm spanner and socket with ratchet and extension Ensure the compressor kit is not damaged when installing. CMPJP-WRNGL-01 Wrangler Compressor Install Guide. Installation Guide Remove spare wheel NSV Automotive L.L.C., P.O. Box 211707, Dubai, UAE. Phone: +971 4 3411422, Fax: +971 4 3411423P0420 Bank 1 and P0430 Bank 2* Codes on 2009 JKU. I have a 2009 JKU and am getting P0420 Bank 1 and P0430 Bank 2 (yes 2 not 1) codes. I have been doing some research and this seems like an odd combination - at least it is to me. She seems to be running good - has 129K miles. These are the only 2 codes present.Code-switching involves not only shifting the way we speak, but also the the way you behave and express yourself. There are many reasons you may do it. If you speak multiple langua...I have been working on older diesel cars for the majority of my life which is why switching over to the 3.8L gasoline jeep has brought me into some unfamiliar territory when emissions codes are being pushed. Recently my jeep has been kicking a P0420 code "Catalyst System Efficency Below Threshold (Bank 1)".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.P0401 is a very common OBDII trouble code that’ll pop up in the Jeep Wrangler. It has to do with the emissions system and stands for Exhaust Gas Recirculation (EGR)→ Insufficient Flow. ... Related: P0420 Jeep Wrangler. Jeep Wrangler P0401 Symptoms. Most of the time, there will not be symptoms associated with P0401 in the …

Killing maggots in dream.

Letters to my husband in jail.

Jeep Grand Cherokee P0420: Catalyst System Efficiency → Below Threshold → Bank 1 | Drivetrain Resource (700r4transmissionhq.com) ... fault codes P0420 and P0430; catalyst efficiency below thresholds, bank 1 and 2. I was in disbelief of a (or 2) catalyst failures on a vehicle with low miles. I have the “right diagnostic equipment” that ...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 .Code P0420 Description. The Engine Control Module (ECM) uses sensors mounted in front of and behind the Three-Way Catalytic Converter (TWC) to monitor its efficiency. The first sensor, the air-fuel ratio sensor, sends pre-catalyst information to the ECM. The second sensor, the heated oxygen sensor, sends post-catalyst information to the ECM.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 …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.FIX: PCM needed to be reprogrammed at the Jeep dealership. 1996 Ford Crown Victoria 4.6L (p0430) Problem: MIL Lamp on (P0430) Diagnosing: Cats and oxygen sensors were all replaced, and yet the check engine still stays on showing the same P0420 code. It turns out that newly installed CATs have an issue.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.The code is logged once a potential airflow issue is detected in the secondary air system. The P0411 code will cause engine performance problems like rough running and lack of acceleration. It can also cause backfiring. It can also cause a rich running condition that can cause poor fuel economy and a noticeable rotten egg smell. ….

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...When the Toyota P0420 code appears, there are several symptoms that may accompany it. These include: 1. Check Engine Light: The most obvious symptom is the illumination of the check engine light on the vehicle's dashboard. This serves as a warning sign that there is an issue with the emissions system. 2.5950 posts · Joined 2008. #2 · Dec 11, 2022. The p0420 is catalyst efficiency code, which could be bad 02 sensors but I've rarely seen replacing both fix this code. You could try running one of the cat cleaner bottles through the fuel tank. I've seen a few videos of folks claiming cataclean works well, and folks running a gallon of laquer ...Save up to 40% on KEH discount code this June 2023. Get new or used camera, lens + tripods for cheap when you use a KEH promo code today for today. PCWorld’s coupon section is crea...The 420/430 are saying Catalytic converter system, efficiency below threshold for both sides. PCM judges this by what the 4 O2s are reporting. The S1s (front) as seen with a OBD-II scanner should bounce around at lot where. the S2s (after CATs) values are stable and less active.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.Jul 29, 2023 · P0420 – Catalyst System Efficiency Below Threshold (Bank1) is an emission/exhaust-related trouble code reporting inefficient operation of your CAT (catalytic converter). It is important not just to confirm a bad catalytic converter, but also to diagnose why it went bad to prevent damage to a newly installed one as they can cost up to $2000. I had a 2016 vehicle today with 25,000 miles, fault codes P0420 and P0430; catalyst efficiency below thresholds, bank 1 and 2. I was in disbelief of a (or 2) catalyst failures on a vehicle with low miles.Labor: 1.0. To diagnose the P0688 Jeep code, it typically requires 1.0 hour of labor. The specific diagnosis time and labor rates at auto repair shops can differ based on factors such as the location, make and model of the vehicle, and even the engine type. It is common for most auto repair shops to charge between $75 and $150 per hour.Apr 26, 2017 · 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 Jeep p0420 code, 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, 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..., Has your check engine light recently turned on? Are you seeing the dreaded error code P0420 on your vehicle’s diagnostic scanner? Don’t panic just yet. Code P0420 is a common issue..., 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., 2011 jeep liberty jet = P0420 Post by rvdsr127 » Sat Oct 11, 2014 1:48 am I TOOK TRIP TO FLD. 3-RD TANK OF GAS I FILL UP AT SHELL GAS & DROVE 20 MILES THE LIGHT CAME ON.I CHECKED THE CAP ,THEN WENT TO ADVANCED AUTO & GOT CARB CLEANER & HAD THEM CHECK CODE (P0420).DROVE BACK TO SC.WITH LIGHT ON..GOT HOME & CLEARED CODE.., The vehicle will not stop working if this isn't addressed, but you may find a small performance/mpg decrease, as the fuel isn't being burned as efficiently as it would. Personally, the only reason I would care is because I wouldn't be able to tell if a new code set the check engine light, because it'd be on all the time for the p0420 code., A subreddit for the Jeep Liberty/Cheerokee. From the 2002 KJ, all the way to the 2012 KK. ... My 3.7L '05 Liberty threw a P0420 code a while back. Had access to AllData which recommended I check the O2 sensors first before replacing the catalytic converter. The only service history I'm aware of for the O2 sensors is the B2S2 sensor I replaced ..., 7 posts · Joined 2016. #1 · Jul 24, 2016. Hi guys, Just got a trouble code P0420 and P0133. It point to 02 Sensor circuit slow response, bank 1 sensor 1. Bought 4 replacement sensor and need help with location of the sensor., 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 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 ..., 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., Even if it isn't causing the p0420 code, it needs to get fixed since you can smell exhaust in the cabin. ... Find answers to all your Jeep Patriot technical questions. Show Less . Full Forum Listing. Explore Our Forums. Jeep Patriot General Discussion Engine and Drivetrain Newbie Check-In Suspension and Tires Electrical and Audio., Trouble code p0420. Jump to Latest Follow. 6K views 8 replies 3 participants last post by TJerry Dec 9, 2014. gel04tj Discussion starter. 30 posts · Joined 2013. #1 · Dec 8, 2014. Check engine light on with this code, replaced both o2 sensors on manifold (code said bank 1) & I used oem mopar sensors. Had code erased & drove it, check engine ..., 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 ..., Google Authenticator can now sync single-use two-factor authentication codes to Google Accounts, for added convenience. Google Authenticator just got an update that should make it ..., 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)., 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 ..., Vibration caused it idk, but it was destroying it's self. Had 58k miles on the Jeep. P0420 should be bank 1 sensor 2. Bank 1 sensor 1 is up stream of the cat that reads AFR/fuel trims, bank 1 sensor 2 reads catalyst efficiency. ... FWIW on my Hyundai's the test for this P0420 or other cat codes is done, after the car has warmed up to at least ..., So I then Called Magnaflow to get me some replacement cats. I ordered Magnaflow 99204HM which are the standard Universal cats for the 3.7L Had them welded on by shop. I reset the Code at the shop and the next day going to work I get Code p0420, Which is Low Bank 1..... Kind of odd that it jumped from Bank 2 to Bank 1 like that., 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 bought a '97 SE and it first popped the O2 code, replaced that and then the P0420 came up **a friend ran a carfax for me and there was an open recall on the Jeep - luckily it still had the factory Cat and the dealer replaced it for free under the recall. They used a mopar universal kit that went from the bottom of the exh. manifold to the ..., =====Claim your FREE engine code eraser 👉 https://free.nonda.co 👈== How to Fix P0420 =====Engine Code P0420 Saving Repair Part..., The p0420 code refers to a fault in the catalytic converter's efficiency, which is an essential component in reducing harmful emissions from the exhaust system. When the converter fails to perform at its optimal level, the engine control module (ECM) detects the anomaly and triggers the p0420 code in the vehicle's On-Board Diagnostic (OBD ..., 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 …, P0420 codes. Jump to Latest Follow ... I am a first time Jeep owner. I had just picked up a 2015 Jeep Wrangler Unlimited Sahara. 3.6 V6 5 speed auto I know the code is a Cat code saying the has restricted flow.. I was just curious on what the possibilities would be on a Cat delete?, 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., The downstream O2 sensor reading should be fairly steady. Typically the P0420 code triggers the Check Engine Light if the readings of the two sensors are similar. This is indicative of (among other things) a converter that is not working as efficiently as it should be (according to specs). ... 2002 Ram 1500 SLT 4x4 QC ~ 02 Ram 45RFE to Jeep GC ..., Code Number Code Description Related Codes P0430 Catalyst System Efficiency Below Threshold (Bank 2) P0420 - Catalyst System Efficiency Below Threshold (Bank 1), P0456 Jeep Code - EVAP System Small Leak - Code Popularity: 127,816 Views - Repair Importance Level: 1/3 - Repair Difficulty Level: 3/3. Table of contents. Created and updated by William Orellana on Mar 25, 2024. Possible Causes;, 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;, 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., 210. Reaction score. 3. Location. Lilburn. I had to disconnect the driver side cat and crossover exhaust pipe (one piece on 2003 Liberty's after 2/2/2003) to change the transmission. I re-installed the original starter with 173k miles when re-assembling the vehicle. Upon startup I got the P0420 cat efficiency code at about 30-50 mile intervals., May 19, 2021 · Diagnostic trouble code(DTC) P0420 stands for “P0420 Catalyst System Efficiency Below Threshold (Bank 1).”. It indicates that the exhaust system’s oxygen levels are below the required threshold in Bank 1, which can damage the engine’s exhaust and fuel system. Bank 1 refers to the side of the engine that houses the number one cylinder.