P0420 Honda CRV 2003: Definition, Indicators, And Fixing

More and more people are trying to find information about the P0420 Honda crv 2003, which brought some troubles to their vehicle.

That also explains our presence today to share some valuable content regarding signs and some causes that triggered the issue.

Digging into the post has meant that you are preparing good knowledge to take better care of your car. Follow us now to get the details.

What Does P0420 Honda CRV 2003 Mean? 

p0420 honda crv 2003
P0420 Honda CRV 2003

The reason behind the Honda CR V P0420 is the car having some problems with the catalytic converter’s efficiency, which is under the threshold.

Honda CRV Code p0420 means your car will be emitting more pollutants.

In addition, once the converter has failed, it will also trigger a wide range of issues on your automobile.

It is clear that black smoke will be leaking from under the car’s engine hood. This isn’t a big fire, yet it would be better if you switched off your engine immediately.

When you continue to speed up, it isn’t hard for you to find the motor running sluggish, and its optimal speed is considerably lower than its typically original level.

What Are Some Indicators Of Honda CRV P0420? 

The P0420 Honda CRV will pop up if one of its oxygen sensors doesn’t work right.

In fact, this kind of incident regarding P0420 rarely happens.

However, according to many experienced drivers, the first sign helping you notice any wrong function on the part is the intermittent flashing Check Engine light.

Below are the common pointers to inform you that the P0420 CRV will come sooner or later.

  • Service engine indicator: this is the most popular symptom; in some cases, this is also only a normal sign on some vehicles.
  • Rotten odor: a sulfur or rotten egg smell is a telltale indicator of a poor catalytic converter.

How To Diagnose The P0420 Code 

code p0420 honda crv
Way To Read The P0420 Code 

Catalytic Converter

The converter is responsible for removing as much contamination as possible from the vehicle’s exhaust manifold.

It might lose the power to filter polluted matter out of its exhaust gasses over time.

Although edge-cutting catalytic systems are equipped to lengthen the longevity of most cars, none of them will stand the test of time.

There might be some potential issues if it has stuck, such as oil seeping into cylinders, a wrong fuel/ air mixture, or a rich misfire.

You can use a heat gun to check the catalytic converter to determine whether it is overheating.

Check For Exhaust Leaks

It sounds like a great idea to inspect your car for some exhaust leaks at first. It isn’t hard to catch a leak with your naked eyes when checking underneath the CRV.

A certain exhaust leak might trigger Honda CRV P0420 code because it makes exhaust fumes seep out unmeasured. In case your automobile does not have a leak, move on to check the oxygen sensor.

O2 Sensor

There are at least 2 oxygen sensors on a Honda CRV, one after and one before the gas enters the catalytic system (known as the downstream oxygen sensors and upstream oxygen sensors).

After the exhaust fumes seep out of the converter, the O2 downstream sensor will determine whether the part is handling its right function.

And before the exhaust fume exits the converter, the upstream sensor will measure the harmful gasses when they hit the engine.

Generally, an O2 sensor is the key root of P0420 Honda CR V. Use a clamp-meter to check this part. Remember to let the exhaust system completely cool down before any test.

After connecting the clamps and switching to the DC mode, turn the engine on and examine the reading.

It should fall somewhere between 0.25 and 1.5A. Otherwise, the O2 sensor is to blame for the code.

O2 Sensor Wiring

When the sensor malfunctions, its wiring should be considered, too. The downstream O2 sensor wiring is more fragile because it’s situated far from the car’s ECM.

Therefore, the catalytic converter might get hot easier.

Inspect Other Codes

To make sure you fix the right code in the vehicle, you need to confirm there are no other error codes.

Below we will list two other codes you can have a glance at to find some key symptoms and know exactly what is going on with your car.

Engine Misfire Codes

If your car gets a code-associated random multi-misfiring code (P0300, P030X- X is the location of its misfiring cylinder), it can heat up your converter.

This issue lessens the cat’s efficiency. And you might mistake it for the P0420 code.

Engine Temperature Sensor Codes

If your vehicle’s computer does not register the engine temp, it will make the fuel mixture concentrated. Once this happens, the exhaust fumes that the Oxygen sensors find would be beyond the limit.

Then it might cause the Honda CR-V P0420 code.

What Are Some Reasons For The P0420 Code Honda Crv

2010 honda crv code p0420
Reasons For The P0420 Code Honda Crv

When it comes to the prevalent roots of the P0420 Code in this kind of Honda car, we can have a look at two separate groups.

Common Reasons

  • Poor O2 sensor
  • Poor catalytic converter
  • Exhaust leak

Other Roots

  • Oxygen sensor wiring
  • PCM trouble
  • The engine did not get the right temperature 
  • Burning oil (often no code, overheats converter)
  • Overheating converter (often triggered by a misfiring engine)
  • Air intake leaks
  • Exhaust tube 
  • Filthy air filter
  • Bad spark plugs 
  • Improper ignition timing
  • Poor fuel injector(s)
  • Faulty ECM (Engine Control Module)

Because there is a wide range of triggers which can end up with the code p0420, you have to inspect each part carefully to find any bad signs on them.

This way, you will get the proper diagnosis and come up with the right solution to fix that.

How To Fix Code P0420 Honda CRV

Before starting to repair the code, you first need to be sure about the root of this issue.

Otherwise, you might end up running your budget more (at least $1000) to purchase a new catalytic converter, even when that was indeed not the reason for the wrong code.

Thus, you need to stick to the above list of causes to find out which one is the culprit and then find the best way to clear the wrong code.

Here we will guide you on how to fix one of the popular causes: Exhaust leak.

You need to equip exhaust RTV, exhaust clamp, exhaust couplers, and tail-pipe expander.

When you find a leak in your exhaust, use a welder to seal it as soon as possible.

In case you don’t have the tool in your house, just detach the bad length of your exhaust, then change that part with a new exhaust coupler.

If the step mucks you around, don’t hesitate to ask for help from an advanced level specialist to address the issue. And for other causes, we highly recommend you visit a repair shop.

Final Thoughts 

We bet you got the key idea for P0420 Honda CRV 2003.

From now on, you have been confident on this issue about some key indicators and main causes. Then, you will find some simple methods to fix that properly.

Thanks for accompanying us. Don’t forget to share this useful post with others looking for thoughtful content, as you did before.     

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