AutoCodes – Chevrolet – P0420 2018 Chevrolet Silverado

P0420 2018 Chevrolet Silverado Code - Catalyst System Low Efficiency Bank 1

Quick Answer

A 3-way catalyst controls emissions of hydrocarbons, Carbon Monoxide (CO), and Nitrogen Oxide (NOx). Common causes include Faulty Three-way Catalyst Converter Bank 1, Exhaust Tube, Intake Air Leaks. 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 Chevrolet Silverado indicates Catalyst System Low Efficiency Bank 1.
Common causes: Common causes include Faulty Three-way Catalyst Converter Bank 1, Exhaust Tube, Intake Air Leaks.
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 787

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 Jun 20, 2022

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 Chevrolet Silverado Description

A 3-way catalyst controls emissions of hydrocarbons, Carbon Monoxide (CO), and Nitrogen Oxide (NOx). The catalyst within the converter promotes a chemical reaction, which oxidizes the hydrocarbons and the CO that are present in the exhaust gas. This process converts the hydrocarbons and the CO into water vapor and carbon dioxide (CO2), and reduces the NOx, converting the NOx into nitrogen. The catalyst also stores oxygen. The Engine Control Module (ECM) monitors this process by using Heated Oxygen Sensors (HO2S) that are in the exhaust stream before and after the 3- way catalyst. The HO2S produces an output signal that the ECM uses to calculate the oxygen storage capacity of the catalyst. This indicates the ability of the catalyst to convert the exhaust emissions efficiently. The ECM monitors the efficiency of the catalyst by monitoring the HO2S during an off-idle, Decel Fuel Cut-Off (DFCO) event. When the catalyst is functioning properly, the post-catalyst HO2S response to the fuel conditions during the DFCO event is slow compared to the response of the pre-catalyst HO2S. When the post-HO2S response is near that of the pre-HO2S, the oxygen storage capability and efficiency of the catalyst may be degraded below an acceptable threshold. The Diagnostic Trouble Code (DTC) will be set when the ECM determines that the efficiency of the catalyst has degraded below a calibrated threshold.

OBDII Code P0420 2018 Chevrolet Silverado - Catalyst System Low Efficiency Bank 1 - AutoCodes.com — P0420 2018 Chevrolet Silverado Code - Catalyst System Low Efficiency Bank 1

What does this mean?

What are the Possible Causes of the DTC P0420 2018 Chevrolet Silverado?

Faulty Three-way Catalyst Converter Bank 1
Exhaust Tube
Intake Air Leaks
Faulty Oxygen (O2) Sensor
Faulty Fuel injector(s)
Leaking Fuel Injector (s)
Faulty Spark plugs
Improper Ignition Timing
Faulty Engine Control Module (ECM)
Dirty Air Filter

How to Fix the DTC P0420 2018 Chevrolet Silverado?

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 control module has detected that the three-way catalytic converter is not working properly (it is not as efficient as the factory is expecting). Replacing the oxygen (O2) sensors may sometimes fix the code, but in most cases, the catalytic convert needs to be replaced to fix the problem. If the P0420 code is combined with other codes, try fixing the other codes first.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0420 2018 Chevrolet Silverado 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.

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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 Chevrolet Silverado Code

1. What are the common symptoms of a P0420 code in a 2018 Chevrolet Silverado?

The common symptoms include the check engine light coming on, decreased fuel efficiency, and potential lack of power during acceleration.

2. What are the possible causes of a P0420 code in a 2018 Chevrolet Silverado?

Potential causes include a faulty catalytic converter, oxygen sensor issues, exhaust leaks, or engine misfires.

3. Can a bad oxygen sensor trigger a P0420 code in a 2018 Chevrolet Silverado?

Yes, a failing oxygen sensor can lead to improper readings and trigger a P0420 code due to incorrect data being sent to the engine control module.

4. How can I diagnose a P0420 code in my 2018 Chevrolet Silverado?

Diagnosing a P0420 code typically involves checking the catalytic converter, oxygen sensors, and exhaust system for any issues using a scan tool and performing a visual inspection.

5. Is it safe to continue driving with a P0420 code in a 2018 Chevrolet Silverado?

It is generally safe to drive with a P0420 code, but it is essential to address the underlying issue promptly to prevent potential damage to the catalytic converter and ensure optimal vehicle performance.

6. Can I reset the P0420 code in my 2018 Chevrolet Silverado with a scan tool?

Yes, you can reset the code with a scan tool; however, it is recommended to diagnose and fix the root cause of the issue to prevent the code from reoccurring.

7. How much does it typically cost to repair a P0420 code in a 2018 Chevrolet Silverado?

The cost of repairing a P0420 code can vary depending on the underlying issue, but it may range from a few hundred to over a thousand dollars, especially if the catalytic converter needs replacement.

8. Will a P0420 code in a 2018 Chevrolet Silverado affect the vehicle's emissions?

Yes, a P0420 code indicates low catalytic converter efficiency, which can lead to increased emissions from the vehicle. It is crucial to address the issue to maintain proper emission levels.

9. Are there any DIY repair tips for a P0420 code in a 2018 Chevrolet Silverado?

While DIY repairs are possible for some causes of a P0420 code, such as replacing oxygen sensors, diagnosing and fixing issues related to the catalytic converter may require professional expertise and equipment.

10. How long does it typically take to repair a P0420 code in a 2018 Chevrolet Silverado?

The repair time for a P0420 code can vary based on the specific cause and complexity of the issue. Simple fixes like replacing an oxygen sensor may take less than an hour, while addressing catalytic converter problems could take several hours or more.