Toyota cars are known for their quality and reliability however like any other car they can have problems from time to time one of the most common problems is the P0420 code in this post we will discuss the meaning of the p420 code in a Toyota its causes symptoms and fixes the P0420 code is a diagnostic trouble code DTC for catalyst system efficiency below threshold meaning that the vehicle emissions output may be higher than normal Toyota P 0420 code causes one faulty oxygen sensor the oxygen sensor is responsible for monitoring the air fuel mixture it works by measuring the amount of oxygen in the exhaust if there is too much oxygen it means that the mixture is too lean conversely if there is not enough oxygen it means that the mixture is too rich two faulty air fuel sensor the air fuel sensor is responsible for monitoring the air to fuel ratio ratio it works by measuring the amount of oxygen in the exhaust gas if there is too much oxygen it means that the air fuel mixture is too lean three leak in the exhaust system a leak in the exhaust system can cause the P0420 code to trigger the most common cause of this is a cracked exhaust manifold when the exhaust manifold cracks the gas will leak out and cause the P0420 code to trigger four engine misfire when you're getting a P0420 code on your Toyota your likely experiencing a misfire or a rough Idol these are both common symptoms of this particular code and they can be caused by several different things in most cases it's due to an issue with the catalytic converter but it could also be due to a problem with the oxygen sensor the spark plugs or the fuel injectors in case you're experiencing a misfire likely one or more of your cylinders is not functioning correctly this can cause a rough idle and may even cause your engine to stall in some cases you may also also notice a decrease in power and fuel economy five leaded gasoline while leaded gasoline is not as common as it used to be it can still be a cause of the P0420 code in Toyota vehicles if your vehicle was built before 1996 you are likely using Leed gasoline if you have recently switched to unleaded gasoline and are still getting the P0420 code this could be the cause lead deposits can build up on the oxygen sensor and prevent it from working properly six rich or lean fuel ratio a P0420 code may be caused by a rich or lean fuel condition if the air fuel mixture is too rich it will cause the oxygen sensor to produce a false lean signal conversely if the mixture is too lean it will cause the oxygen sensor to produce a false Rich signal when your Toyota's OBD2 system detects a lean condition too much air and not enough fuel it will set a P0420 code a rich condition too much fuel and not enough air will cause the OBD2 system to set a p0421 code when troubleshooting this code it is important to check the fuel trim values if the fuel trim values are within normal range then the problem is most likely caused by an exhaust leak seven damag catalytic converter this is the most common cause of the P0420 code the catalytic converter is a vital part of your car's emissions control system and it helps to convert harmful gases into less harmful ones a damag catalytic converter can't do its job properly and this will trigger the the P0420 code eight wrong placement of catalytic converter another reason your check engine light may be triggered is due to the catalytic converter being placed in the wrong spot when the catalytic converter is placed too close to the engine it can overheat and cause damage this will trigger the P0420 code nine oil contamination in the catalytic converter when your engine oil breaks down it can contaminate the catalytic converter this will cause the catalytic converter to fail and the the P0420 code to be triggered you'll need to change your oil and filter to fix this problem Toyota P0420 code symptoms the most common symptom of the P0420 code are one check engine lights on this is the most common symptom of the P0420 code the catalytic converter is an emission control device so when it's not functioning properly the check engine light will come on until the problem is fixed two increased fuel economy when the catalytic converter isn't operating properly your car will have to work harder to make the same amount of power this puts extra strain on the engine which can lead to decreased fuel economy if you notice that your gas mileage has decreased significantly it could be due to a problem with the catalytic converter three lack of power from the engine a catalytic converter that is not working properly will cause the engine to run less efficiently this can lead to a loss of power which may be one of the first symptoms you notice if your Toyota has this problem it may also produce black smoke from the exhaust pipe four sulfur smell when your Toyota is burning sulfur it will produce a rotten egg smell if you notice this while your car is running take it to a mechanic right away as it indicates that your catalytic converter needs to be replaced how to fix P 0240 Toyota code there are a few things you can do to try and fix this code yourself including cleaning the catalytic converter replace catalytic converter replace front or rear oxygen sensor repair damage sensor wiring fix oil burn fix misfires fix lean or Rich fuel mixture replace engine control unit how much does it cost to fix the P0420 code the cost to fix a P0420 code can vary depending on the severity of the problem and which part is malfunctioning for example if the catalytic converter needs to be replaced it could cost between $500 to $1,500 however if the problem is something as simple as a loose gask cap it might only cost $100 to $200 to fix how long does it take to heat up a catalytic converter it can take anywhere from 20 to 30 for a catalytic converter to heat up enough to start converting gases effectively however once it's heated up it will continue working even after the engine is turned off do fuel injected cars need to warm up no fuel injected cars don't need to warm up in fact it's actually better for them if you don't let them idle for too long before before driving why is it bad to drive with a misfire a misfire can be caused by a number of different things but the most common cause is a problem with the spark plugs driving with a misfire can damage the catalytic converter and other parts of the exhaust system it can also cause the engine to run less efficiently which will decrease your gas mileage to summarize what we talked about in this video a P0420 code in a Toyota means there's a problem with the catalytic converter the most common cause is a def faulty oxygen sensor but it could also be caused by a loose gas cap or a problem with the engine to fix the problem you'll need to take your car to a mechanic and have them diagnose the issue depending on the severity of the problem it could cost anywhere from $100 to $1,500 to fix however there is no fixed price to fix the P0420 code I hope this video helped thank you for watching don't forget to like and follow so you don't miss any of my videos