▷ P0420 Code 【2024】✔️ Solution, Meaning, Symptoms and Causes

Your vehicle has a fault Code P0420 and you don’t know what the cause is? Have you ever wondered: how to clear a P0420 code or what is a P0420 code?

Don’t worry! Here we show you how to SOLVE IT, its Causes, meaning and Symptoms, read on, we explain it all.


Meaning of code P0420

P0420 Code Solution, meaning, symptoms and causes

The diagnostic code P0420 is very common and indicates that there is a failure or deficiency in the TWC catalytic converter, which aims to reduce pollutant emissions, this is a vital component to reduce the environmental impact. The converter has a monitor, which allows to measure its efficiency.

  • What does code P0420 mean on my car? The P0420 code means that the efficiency of the catalytic converter system is below the level.
  • Severity rating of the code: MODERATE severity: if you drive for a long time with this code on, you may cause damage to the engine of the vehicle.
  • Causes of Code P0420: The most likely cause of code P0420 is that you have a faulty catalytic converter, but it may also be due to other causes, it may be due to the oxygen sensor, a fault in the ignition system. Since the cause of this code can be in many variables, it is recommended to take it to the nearest workshop where they will tell you exactly what the reason is.
  • Urgency to repair: for the above-mentioned reason it is necessary to repair the P0420 code as soon as possible to avoid further damage to the emission system and the engine.

This code indicates that the catalytic converter is not working efficiently, which increases the emission of harmful pollutants by the vehicle.


  • Damaged or leaking exhaust pipe.
  • Cylinder misfire.
  • Leaking fuel injectors.
  • Intake air leakage.
  • Incorrect ignition adjustment.
  • Fuel injector(s) failure.
  • Oxygen (O2) sensor has failed.
  • Engine coolant temperature sensor is not working.
  • Oxygen sensor (HO2S) cable damaged or incorrectly connected.
  • Faulty engine control module (ECM).
  • Faulty spark plug(s).
  • Fuel contamination.
  • Dirty air filter.


  • Engine lacks power
  • Sulfur or rotten egg smell
  • Check that the check engine light is on.
  • There is a decrease in the fuel economy of the car

Troubleshoot P0420 code

The first thing you need to do is to diagnose the code to find out what is causing the catalytic converter to fail.

  • Check for exhaust leaks at manifold, piping and catalytic converter.
  • Replace catalytic converter.
  • Check downstream oxygen sensor HO2S, replace if necessary
  • Inspect downstream heated oxygen sensor, replace if necessary.

If you cannot perform this diagnosis yourself at home, it is recommended to take the car to a workshop where they will certainly know exactly what in particular is causing the P0420 error code.


Price to repair a P0420 code

Since it is not known what the specific cause of the P0420 code Obd is, it is not possible to give an exact price to fix it.

But surely you will have to take the car to a workshop where they will diagnose exactly what the problem is and give you a solution, based on this, I can tell you that depending on the rate of the workshop where you take your car, the prices can be close to the following:

Workshop labor: approximately ranges between $ 75 and $ 150, this would be in diagnostic time, to which we would have to add the possible breakdown if you have it, but the fee for the diagnosis of the car, is what I mentioned, approximately.

To the diagnostic price you would have to add the parts of the car you are replacing and the labor. The price will depend on where the part to be replaced is located as well as the type and model of car.

  • Leak in the exhaust system, approximate price between $ 100- $ 200
  • Air system fuel sensor, approximate price between $200-$300.
  • Replacing the car’s oxygen sensor, cost between $275-$500
  • Cost of replacing the catalytic converter $400-$2400


Consult other procedures in the USA


error: Prohibido COPIAR!!