Service bulletin Customer Letter

A bulletin is a manufacturer's communication to its dealers, as NHTSA indexes it. The summary is NHTSA's. The document is the manufacturer's: read it at NHTSA. A bulletin is not a recall, and listing a model year does not mean every vehicle of it is concerned.

The communication, as NHTSA indexes it (as of 2026-10-19)
Type	Service bulletin
NHTSA id	10143222
Published by NHTSA	2018-07-30
Manufacturer's number	Customer Letter
Manufacturer's date	2018-07-10
NHTSA component	ELECTRICAL SYSTEM; ENGINE AND ENGINE COOLING

NHTSA's summary

Customer letter - In some cases, the electronic control module (ECM) misinterprets sensor inputs as a warm-up three-way catalytic converter (TWC) deterioration and turns the malfunction indicator lamp (MIL) on with diagnostic trouble code (DTC) P0420 or DTC P0430 (catalyst system efficiency below threshold) stored.

The document

The document is the manufacturer's. This site does not hold it. NHTSA files a document at one of these two addresses; we have not asked NHTSA which.

Components

Electrical system, Engine

Trouble codes named

P0420, P0430

Vehicles listed
HONDA ACCORD HYBRID	2006, 2007 (the catalog's model; the bulletin names a series or trim of it)

Listing a model year does not mean every vehicle of it is concerned: the document says which.

Other bulletins for the same vehicles and component
A21120A	2023-06-21. Service bulletin. Service News - The navigation clock and date are incorrect. This is due to a limited GPS receiver Capacity resulting in rollover of the internal chip memory; the rollover occurred on January 1, 2022, at 12:00AM local time.
A21120A	2022-02-04. Service bulletin. ServiceNews Article - The clock shows the incorrect time. This issue is due to a limited GPS receiver capacity resulting in "rollover" of the internal chip memory; the "rollover" will occur on January 1, 2022, at 12:00AM local time. As a result, once specific triggers are met, the navigation date and time will be incorrect.
DOR-D8K8Q-02	2019-03-04. Service bulletin. This SKU is a Variable Valve Timing (VVT) Solenoid. The Customer communication requested return of unsold inventory to inspect for possible incorrect wiring. Incorrect VVT solenoid wiring may cause an inability of the variable valve timing system to activate. Inability to activate the variable valve timing system may cause reduced engine performance. Incorrect VVT solenoid wiring may also cause the Malfunction Indicator Light (MIL) to illuminate.
A18070	2018-09-04. Service bulletin. Service bulletin - Emission certification labels that were replaced on a small number of vehicles may have been replaced with a label listing incorrect information. The affected emission labels are replacement service parts, and were not installed at the factory; they were installed during postmanufacturing repairs that required replacement of the underlying part. This will cause the vehicle to be non-compliant with emissions regulations.
Customer Letter	2018-08-06. Service bulletin. Customer letter - In some cases, the electronic control module (ECM) misinterprets sensor inputs as a warm-up three-way catalytic converter (TWC) deterioration and turns the malfunction indicator lamp (MIL) on with diagnostic trouble code (DTC) P0420 or DTC P0430 (catalyst system efficiency below threshold) stored.
Customer Letter	2018-08-06. Service bulletin. Customer letter - In some cases, the electronic control module (ECM) misinterprets sensor inputs as a warm-up three-way catalytic converter (TWC) deterioration and turns the malfunction indicator lamp (MIL) on with diagnostic trouble code (DTC) P0420 or DTC P0430 (catalyst system efficiency below threshold) stored.
Customer Letter	2018-07-30. Service bulletin. Customer letter - In some cases, the electronic control module (ECM) misinterprets sensor inputs as a warm-up three-way catalytic converter (TWC) deterioration and turns the malfunction indicator lamp (MIL) on with diagnostic trouble code (DTC) P0420 or DTC P0430 (catalyst system efficiency below threshold) stored.
Service Bulletin	2018-07-16. Service bulletin. Service bulletin - Due to improvements in battery manufacturing efficiency, once stocks of original IMA batteries are depleted, new battery designs will be available for IMA battery replacement. Each battery type requires that its battery control software be matched to its IMA battery type. Failure to match the software with the battery will result in reduced IMA battery life.
AHPa06212018901	2018-07-16. Service bulletin. Dealer message - Today, June 21, 2018, American Honda is announcing a Warranty Extension for 2006-07 Accord Hybrid vehicles to address the MIL illuminating with DTC P0420 or P0430. Basic Problem - The ECM may misinterpret sensor inputs as deterioration of the warm-up catalytic converter, causing the MIL to illuminate with DTC P0420 (rear bank catalyst system efficiency below threshold [bank 1]) or P0430 (front bank catalyst system efficiency below threshold [bank 2]).
A18-023	2018-07-16. Service bulletin. Service bulletin - In some cases, the ECM misinterprets sensor inputs as a warm-up three-way catalytic converter (TWC) deterioration and turns the MIL on with DTC P0420 or DTC P0430 (catalyst system efficiency below threshold) stored. There are two bulletins to address the TWC deterioration with DTC P0420 or P0430: ? 18-022, Warranty Extension: MIL Is On with DTC P0420 or P0430 (All states Except CA, CT, ME, MA, NY, and VT), for vehicles currently registered in all states except CA, CT, ME, MA, NY, and VT. The warranty on these vehicles is extended 6 months from the launch of this campaign (expires December 31, 2018) or 200,000 miles, whichever comes first. ? 18-023, Warranty Extension: MIL Is On with DTC P0420 or P0430 (CA, CT, ME, MA, NY, and VT Only), for vehicles currently registered in CA, CT, ME, MA, NY, and VT. The warranty coverage is 17 years from the original date of purchase with unlimited mileage for the first year of this warranty extension based on the launch date of this extension. After one year, the coverage changes to 17 years from the original date of purchase or 200,000 miles, whichever comes first.