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Service bulletins for the 2018 Honda Clarity

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.

46 on file from NHTSA, as of 2026-10-19.

By type

By component

By trouble code

Only bulletins with component: Electrical system are shown. Show all

Bulletins, newest first
A18-0902023-11-29. Service bulletin. ELECTRICAL SYSTEM; POWER TRAIN. 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.
ONL6CK092120222022-09-27. Service bulletin. ELECTRICAL SYSTEM. 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.
ONL6PH091520222022-09-22. Service bulletin. FUEL SYSTEM, GASOLINE; ELECTRICAL SYSTEM. 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.
A22090A2022-09-22. Service bulletin. ELECTRICAL SYSTEM. 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.
A21-0082021-02-18. Service bulletin. ELECTRICAL SYSTEM; POWER TRAIN:AUTOMATIC TRANSMISSION:CONTROL MODULE (TCM/PCM/TECM); ENGINE AND ENGINE COOLING. Service Bulletin - The Hybrid System Failure message comes on the MID, and DTC P1D8D (Generator Motor Inverter Short) is stored.
A19-054_version32020-04-16. Service bulletin. ELECTRICAL SYSTEM; FUEL SYSTEM, DIESEL:STORAGE:TANK ASSEMBLY. 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.
A19-0062020-04-16. Service bulletin. FUEL SYSTEM, DIESEL:STORAGE:TANK ASSEMBLY; ELECTRICAL SYSTEM. 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.
A18-0902019-10-29. Service bulletin. ENGINE AND ENGINE COOLING; ELECTRICAL SYSTEM; VISIBILITY. 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).
APOC062720192019-07-04. Service bulletin. VISIBILITY; ELECTRICAL SYSTEM. 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_version22019-06-19. Service bulletin. ELECTRICAL SYSTEM. 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.
A19-0542019-06-12. Service bulletin. FUEL SYSTEM, DIESEL:STORAGE:TANK ASSEMBLY; ELECTRICAL SYSTEM. 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.
A19-0062019-06-12. Service bulletin. FUEL SYSTEM, DIESEL:STORAGE:TANK ASSEMBLY; ELECTRICAL SYSTEM. Service Bulletin - Water improperly discharged inside the fuel cell 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.
ONL6PH032620192019-04-06. Service bulletin. ELECTRICAL SYSTEM; VISIBILITY. Owner Notification Letter - 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.
ONL6CW032620192019-04-06. Service bulletin. ELECTRICAL SYSTEM. Owner Notification Letter - On Clarity Plug-in Hybrid vehicles, the warranty information CD that was placed in the vehicle during vehicle assembly did not list the correct warranty coverage for the state of Oregon.
A18-0972019-03-19. Service bulletin. ELECTRICAL SYSTEM; ELECTRICAL SYSTEM:12V/24V/48V BATTERY. Service Bulletin - The Clarity Plug-In Hybrid and Clarity Electric may not start charging when plugged in or may stop charging before the high-voltage lithium-ion battery is full.
ONL6CK030520192019-03-15. Service bulletin. ELECTRICAL SYSTEM:SOFTWARE; FUEL SYSTEM, OTHER:STORAGE:TANK ASSEMBLY. Owner Notification Letter - On 2017-18 Clarity Fuel Cell vehicles, 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.
ABOM011420199012019-02-10. Service bulletin. ELECTRICAL SYSTEM; EQUIPMENT:ELECTRICAL. "Dealer message - Today American Honda is notifying dealers of two product updates affecting certain 2017-18 Clarity Fuel Cell vehicles. The first is a software update to the hydrogen tank temperature sensors. The second is a product update to replace the fuel cell stack on a limited number of vehicles due to premature deterioration."
A19-0062019-02-10. Service bulletin. FUEL SYSTEM, DIESEL:STORAGE:TANK ASSEMBLY; ELECTRICAL SYSTEM. "Service bulletin - The telematics system is reporting deterioration of the fuel cell stack. This deterioration can reduce fuel cell output. Water improperly discharged inside the fuel cell 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."
A19-0012019-02-10. Service bulletin. ELECTRICAL SYSTEM. "Service bulletin - The vehicle may incorrectly set DTC P1F76 (main hydrogen tank temperature sensor malfunction) or P1F77 (sub hydrogen tank temperature sensor malfunction). The fuel cell communication control (IR) software is not current."
A18-0972018-11-13. Service bulletin. ELECTRICAL SYSTEM. Service bulletin - The Clarity Plug-In Hybrid and Clarity Electric may not start charging when plugged in or may stop charging before the high-voltage lithium-ion battery is full.
ABOM100420189012018-10-15. Service bulletin. ELECTRICAL SYSTEM. Dealer message - Today, American Honda is announcing several product updates a?ecting certain 2018 Honda Clarity Plug-In Hybrid (PHEV) models. There may be multiple combinations of these campaigns per VIN. To clearly identify each vehicle's needs, be sure to do an iN VIN status inquiry for units in dealer inventory and during customer visits. Also, to help ensure customer satisfaction and reduce inconvenience, make sure all parts and software are available when customers arrive. PROBLEM Climate Control: In certain operating conditions, a software issue with the climate control unit and PCM software may lead to incorrect operation of the coolant 3-way valve, causing DTC P26A3 (electric water valve malfunction) to set. Electric Valve Timing Control (EVTC): In certain operating conditions, an issue with the PCM software may lead to incorrect operation of the EVTC, causing DTC P100C (electric VTC motor signal circuit malfunction) and/or P0010 (variable valve timing control [VTC] malfunction) to set. Driver Information Interface: In certain EV mode driving conditions, a software issue with the driver information interface may lead to the HV range reading unusually high (more than 1,000 miles remaining). Warranty information CD placed in the vehicle did not list the correct warranty coverage for the state of Oregon. This may cause customer confusion regarding coverage.
A18-0912018-10-15. Service bulletin. ELECTRICAL SYSTEM. Service bulletin - There is a software error in the miles per gallon calculation, which affects the HV range display by reading unusually high.
A18-0902018-10-15. Service bulletin. ELECTRICAL SYSTEM. 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).
A18-0892018-10-15. Service bulletin. ELECTRICAL SYSTEM:SOFTWARE. Service bulletin - There is a software problem in the climate control unit when running the heater, which may turn the MIL on. There are up to three updates that must be performed on applicable vehicles. Check the iN VIN status inquiry for applicability.
A18-0792018-10-15. Service bulletin. ELECTRICAL SYSTEM. Service bulletin - This bulletin is replaced by S/B 18-089, Product Update: 2018 Clarity Plug-In Hybrid EVTC & 3-Way Valve Software Update (P100C/P0010/P26A3)

The summaries are NHTSA's. Each bulletin's page links NHTSA's copy of the manufacturer's document.