AutoCodes – Honda – P0420 2021 Honda CR-V

P0420 2021 Honda CR-V Code - Catalyst System Efficiency Below Threshold

Quick Answer

The Three-Way Catalytic Converter (TWC) converts Hydrocarbons (HC), Carbon Monoxide (CO), and Oxides of Nitrogen (NOx) in the exhaust gas to water vapor, Carbon Dioxide (CO 2), and Dinitrogen (N 2). Common causes include Faulty Three-Way Catalytic Converter (TWC), Faulty Secondary Heated Oxygen Sensor (Secondary HO2S (Sensor 2)), Secondary Heated Oxygen Sensor 2 harness is open or shorted. Severity is Moderate - service should be scheduled soon. The vehicle may still be drivable for short trips if it runs normally, but avoid hard driving and repair it soon.

What it means: P0420 2021 Honda CR-V indicates Catalyst System Efficiency Below Threshold.
Common causes: Common causes include Faulty Three-Way Catalytic Converter (TWC), Faulty Secondary Heated Oxygen Sensor (Secondary HO2S (Sensor 2)), Secondary Heated Oxygen Sensor 2 harness is open or shorted.
Severity: Moderate - service should be scheduled soon.
Can I drive?: The vehicle may still be drivable for short trips if it runs normally, but avoid hard driving and repair it soon.

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Code Popularity 535

How popular is this code, among other codes? Low

Repair Importance Level

Moderate (Service soon) (2 / 3)

Repair Difficulty Level

Intermediate (2 / 3)

What is this?

Table of contents Created and updated by William Orellana on Aug 18, 2023

Description
Step-by-Step Diagnostic Guide
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
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Code P0420 2021 Honda CR-V Description

The Three-Way Catalytic Converter (TWC) converts Hydrocarbons (HC), Carbon Monoxide (CO), and Oxides of Nitrogen (NOx) in the exhaust gas to water vapor, Carbon Dioxide (CO 2), and Dinitrogen (N 2). The Powertrain Control Module (PCM) fluctuates the air/fuel ratio temporarily to detect the performance of the TWC and measures the degree of fluctuation in the secondary Heated Oxygen Sensor (Secondary HO2S (Sensor 2)) output. If the accumulated value for a set time is too great, deterioration of the performance of the catalyst is detected, and the PCM detects a malfunction and stores a Diagnostic Trouble Code (DTC).

OBDII Code P0420 2021 Honda CR-V - Catalyst System Efficiency Below Threshold - AutoCodes.com — P0420 2021 Honda CR-V Code - Catalyst System Efficiency Below Threshold

What does this mean?

What are the Possible Causes of the DTC P0420 2021 Honda CR-V?

Faulty Three-Way Catalytic Converter (TWC)
Faulty Secondary Heated Oxygen Sensor (Secondary HO2S (Sensor 2))
Secondary Heated Oxygen Sensor 2 harness is open or shorted
Secondary Heated Oxygen Sensor 2 circuit poor electrical connection

How to Fix the DTC P0420 2021 Honda CR-V?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What does this mean?

Code Tech Notes

As the code description implies, the P0420 code means that the vehicle's Powertrain Control Module (PCM) has detected that the Three-way Catalyst Converter is not working properly (it is not as efficient as the factory expects). Replacing the oxygen (O2) sensors may sometimes fix the code, but in most cases, the Three-way Catalyst Converter needs to be replaced to resolve the problem. If the P0420 code is combined with other codes, try addressing the other codes first.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0420 2021 Honda CR-V code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

Need more information about the P0420 2021 Honda CR-V code?

Need more information on how to fix the P0420 2021 Honda CR-V code? Get Access to Factory Service Manuals

Need Help with the Code?

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about P0420 2021 Honda CR-V Code

1. What are the common symptoms of OBDII code P0420 in a 2021 Honda CR-V?

- Common symptoms include a check engine light illuminated on the dashboard, decreased fuel efficiency, and potential issues with the vehicle's performance.

2. What are the possible causes of the P0420 code in a 2021 Honda CR-V?

- Causes can vary, but common ones include a faulty catalytic converter, oxygen sensor issues, exhaust leaks, or engine misfires.

3. How serious is the P0420 code in a 2021 Honda CR-V?

- While the vehicle may still be operable, it is important to address this issue promptly to prevent further damage to the catalytic converter and to ensure optimal engine performance.

4. Can I continue driving my 2021 Honda CR-V with the P0420 code?

- It is generally not recommended to drive the vehicle for an extended period with this code present, as it can lead to increased emissions and potential damage to other engine components.

5. How can I diagnose the P0420 code in my 2021 Honda CR-V?

- A professional diagnostic scan tool can help pinpoint the root cause of the issue by reading data from the vehicle's onboard computer system.

6. What are some possible repair options for the P0420 code in a 2021 Honda CR-V?

- Repair options may include replacing the catalytic converter, addressing oxygen sensor malfunctions, fixing exhaust leaks, or resolving engine misfires.

7. Can I reset the check engine light after addressing the P0420 code in my 2021 Honda CR-V?

- Yes, once the underlying issue has been resolved, the check engine light can be reset using a diagnostic scan tool to clear the code.

8. How much does it typically cost to repair the P0420 code in a 2021 Honda CR-V?

- Repair costs can vary depending on the specific cause of the issue, but expect to budget for parts and labor related to the catalytic converter, oxygen sensors, or other components.

9. Are there any preventive maintenance tips to avoid the P0420 code in a 2021 Honda CR-V?

- Regular maintenance, such as timely oil changes, ensuring proper fuel quality, and addressing engine issues promptly, can help prevent catalytic converter and emission system problems.

10. Will the P0420 code affect my 2021 Honda CR-V's emissions test results?

- Yes, the presence of the P0420 code may cause your vehicle to fail emissions tests, as it indicates a problem with the catalyst system's efficiency.