2021-2024 Honda Accord, Civic, CR-V P0420 CEL Investigation

Background on the Investigation

American Honda Motor Co., Inc. (AHM) has initiated an investigation into specific 2021-2024 Honda Accord, Civic, and CR-V models experiencing a "Check Engine Light (CEL)" illuminated on the dashboard. This investigation specifically targets vehicles that have stored Diagnostic Trouble Code (DTC) P0420, indicating "Catalyst System Efficiency Below Threshold." The goal is to collect certain vehicle parts for analysis to better understand the underlying cause of this condition before any repairs are attempted.

This manufacturer communication, identified as NHTSA ID 11011792, is a request for parts from qualifying vehicles. Honda aims to gather data to pinpoint the exact cause of the P0420 fault code before issuing any repair procedures.

Symptoms

Owners of affected Honda vehicles may notice their "Check Engine Light (CEL)" illuminated on the instrument cluster. When scanned, the vehicle's onboard diagnostic system will show the DTC P0420, which signifies that the catalytic converter's efficiency has fallen below acceptable limits. This condition, often referred to as "Catalyst System Efficiency Below Threshold," suggests a potential issue with the emissions control system.

Qualifying Conditions for Participation

Honda is interested in collecting parts only if the vehicle meets a specific set of requirements. For 2021-2024 Honda Accord, Civic, and CR-V models, the vehicle must:

• Have DTC P0420 stored.
• NOT have any of the following DTCs stored: P030X, P0171, P0172, or P0299.
• Be equipped with a 1.5L turbo engine.
• NOT have had a previous replacement of the Catalytic Converter (part number 18150), Oxygen Sensor (part number 36532), LAF sensor (part number 36531), Fuel injectors (part numbers 06160/16010), or the Turbocharger (part number 18900).

If the DTC P0420 code was previously cleared, it is acceptable if it can be confirmed through the Honda Diagnostic System (HDS) with an "All DTC Check" printout. Crucially, no repair should have been attempted for the P0420 issue prior to contacting Honda.

Important Warnings for Owners

It is critical for owners to understand that Honda's request is for data collection, not an immediate repair. If your vehicle meets the qualifying conditions for the Honda P0420 CEL investigation, it is important that no repair has been attempted for this issue before contacting your dealership. Attempting repairs may disqualify your vehicle from participating in this investigation and could hinder Honda's ability to diagnose the root cause.

What Owners Should Do

If your 2021-2024 Honda Accord, Civic, or CR-V displays a "Check Engine Light (CEL)" with DTC P0420 and meets all the qualifying conditions, you should contact your authorized Honda dealership. The dealership will then need to communicate with Honda's Technical Information & Support (TIS) group. They will provide vehicle information, including the model year, model name, VIN, current mileage, and a printout of all DTCs, to TIS via email at [email protected] or by calling 800-880-1072 (Monday-Friday, 7am-5pm PST).

This process allows Honda to collect the necessary parts for analysis. Owners should be aware that this is part of an ongoing investigation to understand the Honda P0420 CEL issue better, and specific repair instructions will follow once the root cause is determined.

Fault Codes and Related Components

This investigation focuses on Diagnostic Trouble Code (DTC) P0420, which indicates "Catalyst System Efficiency Below Threshold." Other DTCs that would disqualify a vehicle from this investigation include P030X (cylinder misfire), P0171 (system too lean), P0172 (system too rich), and P0299 (turbocharger underboost).

Components that must not have been previously replaced in qualifying vehicles include:

• Catalytic Converter: Part numbers 18150 (for Accord, Civic, CR-V) and 18190 (for Fit, though Fit models are not listed in the NHTSA scope for this document).
• Oxygen Sensor: Part number 36532.
• LAF sensor: Part number 36531.
• Fuel injectors: Part numbers 06160/16010.
• Turbocharger: Part number 18900.
• Throttle body: Part number 16400.
• High Pressure Fuel Pump: Part number 06161.

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Source: NHTSA ID: 11011792