Service bulletin A18-090

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	10145430
Published by NHTSA	2018-10-15
Manufacturer's number	A18-090
Manufacturer's date	2018-10-06
NHTSA component	ELECTRICAL SYSTEM

NHTSA's summary

Service bulletin - There is a software problem in the PCM, which may cause the MIL to come on with DTC P26A3 (electric water valve malfunction), DTC P100C (electric VTC motor speed signal circuit malfunction) and/or P0010 (variable valve timing control [VTC] malfunction).

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

Trouble codes named

P0010, P100C, P26A3

Vehicles listed
HONDA CLARITY ELECTRIC	2018 (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.

Recalls for the same vehicles and component
18V921000	2018-12-20. ELECTRICAL SYSTEM:SOFTWARE; HYBRID PROPULSION SYSTEM

A recall listed here may apply to some of the same vehicles. Only the manufacturer can say whether it applies to one vehicle.

Other bulletins for the same vehicles and component
A18-090	2023-11-29. Service bulletin. Service Bulletin - There is a software problem in the PCM, which may cause the MIL to come on with DTC P26A3 (electric water valve malfunction), DTC P100C (electric VTC motor speed signal circuit malfunction) and/or P0010 (variable valve timing control [VTC] malfunction). There are up to three updates that must be performed on applicable vehicles.
ONL6CK09212022	2022-09-27. Service bulletin. Owner's Notification Letter - Product Update - Our records indicate that a Product Update has not been completed on this vehicle (Vehicle Identification Number XXXXXXXXXXXXXXXXX). The software that monitors the temperature in the fuel cell tank may not be up to date. This may cause the vehicle to incorrectly display a hydrogen system warning on the instrument panel and store a system malfunction.
ONL6PH09152022	2022-09-22. Service bulletin. Owner's Notification Letter - Our records indicate that a PRODUCT UPDATE has not been completed on this vehicle (Vehicle Identification Number [VIN NUMBER]). On Clarity Plug-in Hybrid vehicles, there is a software error in the miles per gallon calculation, which affects the HV range display and causes it to read unusually high.
A22090A	2022-09-22. Service bulletin. Dealer Message - In the event you experience a sub tank wire harness rodent damage on the 2017–2020 Clarity FCV, after repairing / replacing the wire harness, wrap the areas shown below with RODENT DETERRENT TAPE, P/N 4019-2317.
A21-008	2021-02-18. Service bulletin. Service Bulletin - The Hybrid System Failure message comes on the MID, and DTC P1D8D (Generator Motor Inverter Short) is stored.
A19-054_version3	2020-04-16. Service bulletin. Service Bulletin - The fuel cell (FC) system uses an electric water pump to circulate insulating fluid and remove excess heat from the fuel cell stack. During manufacturing, the water pump's magnetic surface was not treated for corrosion resistance. Over time, the corrosion may prevent the water pump's motor from starting, which will prevent the vehicle from starting. If this happens while driving, the vehicle can only be driven for a short distance at greatly reduced power.
A19-006	2020-04-16. Service bulletin. Service Bulletin - Water improperly discharged inside the fuel cell (FC) stack mixes with hydrogen and oxygen, generating hydrogen peroxide. The hydrogen peroxide/water combination concentrates in one area, accelerating the deterioration of the electrolyte membrane in the fuel cell. This deterioration can reduce fuel cell output.
A18-090	2019-10-29. Service bulletin. Service Bulletin - There is a software problem in the PCM, which may cause the MIL to come on with DTC P26A3 (electric water valve malfunction), DTC P100C (electric VTC motor speed signal circuit malfunction) and/or P0010 (variable valve timing control [VTC] malfunction).
APOC06272019	2019-07-04. Service bulletin. Dealer Message - On October 4, 2018, American Honda announced several Product Update Campaigns for certain 2018 Honda Clarity Plug-In Hybrid (PHEV) models. Replacement CPU Assembly Auto AC Kits and Warranty CD's were available at the time of bulletin launch.
A19-054_version2	2019-06-19. Service bulletin. Service Bulletin - The fuel cell (FC) system uses an electric water pump to circulate insulating fluid and remove excess heat from the fuel cell stack. During manufacturing, the water pump's magnetic surface was not treated for corrosion resistance. Over time, the corrosion may prevent the water pump's motor from starting, which will prevent the vehicle from starting. If this happens while driving, the vehicle can only be driven for a short distance at greatly reduced power.