Reference meaning
What does this code mean?
The wording below belongs to the named make and communication. Match the complete code, reporting module, model year and engine before applying it.
A code identifies a detected condition, not a part that must automatically be replaced.
Narrow by vehicle
A listed vehicle is a research lead. Confirm the engine, production range and software in the manufacturer's information.
Before replacing a part
Record codes and freeze-frame data. Check battery condition, related codes and visible wiring or hose damage. Follow the vehicle's diagnostic procedure and test results before replacing parts.
Scan worksheet →Manufacturer communications
4Original wording in English
TOYOTA
TSB: Some 2016 ? 2019 model year Mirai vehicles may exhibit a warning message, ?FC malfunction, return vehicle to dealer for service.? This message is accompanied by Diagnostic Trouble Code (DTC) P1DEF (450 FC Stack Performance). The Fuel Control Module (FCM) calibration has been revised to address this condition
TOYOTA
TSB: REVISION NOTICE September 20, 2019 Rev2: ? Applicability has been updated to include 2018 and 2019 model year Mirai vehicles. ? The Production Change Information, Parts Information, and Calibration sections have been updated. September 5, 2018 Rev1: ? The Parts Information section has been updated. Some 2016 ? 2019 model ye…
TOYOTA
TSB: REVISION NOTICE September 5, 2018 Rev1: ? The Parts Information section has been updated. Any previous printed versions of this bulletin should be discarded. Some 2016 ? 2017 model year Mirai vehicles may exhibit a warning message, "FC malfunction, return vehicle to dealer for service." This message is accompanied by Diagno…
TOYOTA
TSB: Some 2016 ? 2017 model year Mirai vehicles may exhibit a warning message, "FC malfunction, return vehicle to dealer for service." This message is accompanied by Diagnostic Trouble Code (DTC) P1DEF (450 FC Stack Performance). The Fuel Control Module (FCM) calibration has been revised to address this condition.
Check vehicle applicability
4A listed vehicle is a research lead. Confirm the engine, production range and software in the manufacturer's information.
Can I keep driving?
A code alone cannot establish whether driving is safe. A flashing malfunction light, severe shaking, overheating, oil-pressure warning or loss of braking or steering needs prompt attention. Stop in a safe place and seek assistance when control or engine safety is affected. Follow the vehicle handbook.