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

Honda is currently conducting an investigation into customer complaints of a "Check Engine Light (CEL)" illuminating due to a stored "DTC P0420 [Catalyst System Efficiency Below Threshold]". This effort, outlined in a "Request for Parts" message, aims to gather specific vehicle components to better understand the root cause of this condition before any repairs are performed.

The investigation primarily focuses on 2018-2024 Honda Accord 1.5L models, 2021-2024 Honda Civic 1.5L models, 2023-2024 Honda CR-V 1.5L models, and 2017 Honda Fit vehicles. If your vehicle, such as a Honda CR-V P0420, is experiencing these symptoms, it might be part of this important data collection.

Symptoms

Owners of affected vehicles will typically observe the illumination of the "Check Engine Light (CEL)" on their dashboard. Diagnostic scanning of the vehicle's onboard computer system will reveal the presence of the diagnostic trouble code (DTC) P0420, often described as "Catalyst System Efficiency Below Threshold".

Relevant Diagnostic Trouble Codes (DTCs)

The primary DTC of interest for this investigation is P0420. However, Honda is specifically looking for vehicles that do not also have certain other codes stored. This helps narrow down the specific conditions they are trying to understand.

Code	Description
P0420	Catalyst System Efficiency Below Threshold
P030X	Cylinder Misfire (e.g., P0301, P0302)
P0171	System Too Lean (Bank 1)
P0172	System Too Rich (Bank 1)
P0299	Turbocharger/Supercharger Underboost

For a vehicle to qualify for this investigation, it must only have P0420 stored, without any of the P030X, P0171, P0172, or P0299 codes.

Specific Conditions for Investigation

Honda is interested in vehicles that meet very specific criteria to ensure the collected parts are relevant to their study. These conditions vary slightly between the Accord, Civic, CR-V models and the Fit model.

For 2018-2024 Accord, 2021-2024 Civic, and 2023-2024 CR-V models, the vehicle must:

• Have DTC P0420 stored.
• Not have DTCs P030X, P0171, P0172, or P0299 stored.
• 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 Turbocharger (part number 18900).

For 2017 Honda Fit models, the vehicle must:

• Have DTC P0420 stored.
• Not have DTCs P030X, P0171, P0172 stored.
• Not have had a previous replacement of the Catalytic Converter (part number 18190), Oxygen Sensor (part number 36532), Air Fuel Ratio Sensor (part number 36531), Throttle body (part number 16400), or High Pressure Fuel Pump (part number 06161).

In all cases, it is acceptable if the DTC code was previously cleared, provided it can be confirmed through Honda Diagnostic System (HDS) with a printout of all DTC checks. Crucially, no repair attempt should have been made for the issue.

What Owners Should Know

This communication, identified as a "Request for Parts" message, is directed solely to Honda dealership personnel. This means that Honda is not directly notifying consumers about this investigation. Owners must proactively engage with their dealership if they believe their vehicle meets the specified criteria. It's also important to note that Honda is looking for vehicles where no repair has been attempted for this issue yet. If you have a Honda CR-V P0420 fault, ensure no prior repair has been done.

Next Steps for Owners

If your 2021-2024 Honda Accord, Civic, or CR-V, or your 2017 Honda Fit, is displaying a "Check Engine Light (CEL)" with DTC P0420 and meets the specific qualifiers mentioned above, you should contact your authorized Honda dealership. The dealership will then communicate with Honda's Technical Information & Support (TIS) team. TIS will require specific vehicle information, including:

• Model Year
• Model Name
• A description of the issue (e.g., "Check Engine Light with P0420")
• Your Vehicle Identification Number (VIN)
• Dealer Number
• Your Name and Best Phone Number
• Current Mileage
• Confirmation that the vehicle meets all qualifiers
• An attached printout of all DTC checks from the HDS system
• The DPTS# (Dealer Parts Tracking System number)

Dealership personnel who successfully identify and report a qualifying vehicle that is accepted for the program may receive a VISA gift card as an appreciation gesture from AHM.

Source: NHTSA Manufacturer Communication 11010549.