AutoCodes – Honda – P0420 2018 Honda CR-V

P0420 2018 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 2018 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 545

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 2018 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 2018 Honda CR-V - Catalyst System Efficiency Below Threshold - AutoCodes.com — P0420 2018 Honda CR-V Code - Catalyst System Efficiency Below Threshold

What does this mean?

What are the Possible Causes of the DTC P0420 2018 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 2018 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 2018 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 2018 Honda CR-V code?

Need more information on how to fix the P0420 2018 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 2018 Honda CR-V Code

1. What are the common symptoms of OBDII code P0420 in a 2018 Honda CR-V?

The common symptoms of code P0420 in a 2018 Honda CR-V include decreased fuel efficiency, the Check Engine light illuminated on the dashboard, and potential loss of engine power.

2. What does the OBDII code P0420 "Catalyst System Efficiency Below Threshold" mean for a 2018 Honda CR-V?

The P0420 code indicates that the catalytic converter in the exhaust system of the 2018 Honda CR-V is not performing as efficiently as it should in reducing harmful emissions.

3. What are the potential causes of OBDII code P0420 in a 2018 Honda CR-V?

Common causes of code P0420 in a 2018 Honda CR-V include a failing catalytic converter, oxygen sensor issues, exhaust leaks, engine misfires, or a faulty mass airflow sensor.

4. Can driving habits trigger OBDII code P0420 in a 2018 Honda CR-V?

Yes, frequent short trips or stop-and-go driving can contribute to the buildup of deposits in the catalytic converter, potentially triggering code P0420 in a 2018 Honda CR-V.

5. How can I diagnose the OBDII code P0420 in my 2018 Honda CR-V?

Diagnosing code P0420 usually involves using an OBDII scanner to read the code, checking the oxygen sensor data, inspecting the catalytic converter for physical damage, and looking for exhaust leaks.

6. What are some repair tips for resolving OBDII code P0420 in a 2018 Honda CR-V?

Repair options for addressing code P0420 in a 2018 Honda CR-V may include replacing the catalytic converter, oxygen sensors, fixing exhaust leaks, ensuring proper engine maintenance, or using fuel system cleaners.

7. Is it safe to continue driving a 2018 Honda CR-V with OBDII code P0420?

While the vehicle may still be operable with code P0420, it is recommended to address the issue promptly to prevent further damage to the catalytic converter and ensure optimal engine performance.

8. Can resetting the Check Engine light clear OBDII code P0420 in a 2018 Honda CR-V?

Resetting the Check Engine light may temporarily clear the code P0420, but if the underlying issue is not addressed, the code is likely to reappear after the vehicle goes through its emission readiness tests.

9. How much does it typically cost to repair OBDII code P0420 in a 2018 Honda CR-V?

The cost of repairing code P0420 in a 2018 Honda CR-V can vary depending on the specific cause, but it may range from a few hundred dollars for replacing oxygen sensors to over a thousand dollars for a new catalytic converter.

10. Can aftermarket catalytic converters be used to replace a faulty one triggering OBDII code P0420 in a 2018 Honda CR-V?

While aftermarket catalytic converters may be a more affordable option, it is essential to ensure that they meet the necessary quality and emission standards to avoid potential issues with performance or triggering the code again.