FC CONTROL SYSTEM, Diagnostic DTC:P1E44-450

DTC Code	DTC Name
P1E44-450	Hydrogen Pressure Leak (Low Pressure Area)

DESCRIPTION

The hydrogen system of the FC system feeds the FC stack with hydrogen, so that the FC stack can generate power.

The low-range pressure line located after the hydrogen injectors are called a hydrogen circulation system line, and its internal pressure is properly regulated by the hydrogen injectors for FC stack power generation.

Pressures in the low-range pressure line is monitored by the system, and if the internal pressure decreases despite the hydrogen injectors and exhaust drainage valve being closed, this will be interpreted as external leaks, and this DTC will be set.

For the circuit diagram, refer to DTC P1DC0-450.

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DTC No.	Detection Item	DTC Detection Condition	Trouble Area	Warning Indicate
P1E44-450	Hydrogen Pressure Leak (Low Pressure Area)	Following malfunction detection is active while the mode is in FC Startup Process or FC Working (FC Intermittent Operation). Hydrogen injectors and exhaust drainage valve are forced to close to shut off the hydrogen circulation system line (low-range pressure system) for checking if a pressure decrease has occurred in the system line so as to detect hydrogen leakage. (1 trip detection logic)	FC stack assembly (exhaust drainage valve, low-range hydrogen pressure sensor, FC stack, sealed area of each component)	Master Warning Light: Comes on

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

Warning Indicate

P1E44-450

Hydrogen Pressure Leak (Low Pressure Area)

Following malfunction detection is active while the mode is in FC Startup Process or FC Working (FC Intermittent Operation).

Hydrogen injectors and exhaust drainage valve are forced to close to shut off the hydrogen circulation system line (low-range pressure system) for checking if a pressure decrease has occurred in the system line so as to detect hydrogen leakage.

(1 trip detection logic)

FC stack assembly (exhaust drainage valve, low-range hydrogen pressure sensor, FC stack, sealed area of each component)

Master Warning Light: Comes on

Tech Tips

This DTC indicates leaks from the low-range hydrogen pressure system located after the hydrogen injectors.

Detection timing
Vehicle Condition	FC shutdown (power switch on (IG))	FC startup process	FC intermittent operation	FC is generating power (vehicle is in stationary)	FC is generating power (vehicle is traveling)	FC shutdown process
Data List "FC Mode"	FC Shutdown	FC Startup Process	FC Working			FC Shutdown Process
Data List "FC Intermittent Operation"	OFF		ON	OFF		OFF
DTC Detection	-	○	○	-	-	-

Related Data List
DTC No.	Data List
P1E44-450	Smoothed Value of Low-range Hydrogen Pressure

The following items can be helpful when performing repairs:

Data List

Target Low-range Hydrogen Pressure
Tank Side Hydrogen Detector Density
Motor Room Side Hydrogen Detector Density
Tank Shut Valve 1 Driving Request
Tank Shut Valve 2 Driving Request
Hydrogen Injector 1 Injection Request
Hydrogen Injector 2 Injection Request
Hydrogen Injector 3 Injection Request
Smoothed Value of High-range Hydrogen Pressure
Smoothed Value of Medium-range Hydrogen Pressure
Exhaust Drainage Valve Driving Request

Common Data List items for FC inspection

Vehicle Speed
Shift Sensor Shift Position
Accelerator Degree
Ready
FC Mode
FC Intermittent Operation
FC Voltage before Boosting
FC Current
Target Hydrogen Pump Revolution
Hydrogen Pump Revolution
Target FC Stack Air Pressure (FC Stack Inlet)
Smoothed Value of FC Stack Air Pressure (FC Stack Inlet)
Target Mass Air Flow Value
Mass Air Flow Value
Target Air Compressor Revolution
Air Compressor Revolution
Target FC Stack Coolant Temperature (FC Stack Outlet)
Smoothed Value of FC Stack Coolant Temperature (FC Stack Outlet)

Related Active Test
DTC No.	Active Test
P1E44-450	Hydrogen Injector

CAUTION / NOTICE / HINT

CAUTION:

Work procedures must be performed in an area with good ventilation (airflow) where hydrogen gas will not accumulate, and flames or other things that could act as ignition sources must not be present.
Accumulated hydrogen gas could ignite, resulting in a serious accident.

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Note

After completion of repair, check that no hydrogen leaks from the hydrogen pipes using a hydrogen gas detector.
When the vehicle is parked with the power switch off, if the FC control ECU judges that the FC stack temperature will go below 0°C (32°F), it activates the FC air compressor, hydrogen pump and FC cooling water pump for a maximum of 180 seconds and drains water from the FC stack assembly. When performing inspection or repairs with the power switch off (not on (IG) or on (READY)), disconnect the cable from the negative (-) auxiliary battery terminal before performing work (If the auxiliary battery voltage is needed to conduct inspection, warm up the FC system beforehand).

Tech Tips

Forcing the SOC of the EV battery to decrease by applying electrical loads such as turning on the air conditioning (HOT MAX, maximum airflow), or depressing the accelerator pedal with the shift lever in P, the "FC Intermittent Operation" of the Data List is easily to enter OFF (power generation mode).

After the repair, clear the DTCs and perform the following procedure to check that DTCs are not output.

Turn the power switch on (READY) with the shift lever in P, and check the Data List that "FC Mode" is FC Working. Then, wait for 1 minute or more (If FC system cannot be activated, check the DTCs that are present at the time).
Turn the Power switch off and wait for 3 minutes or more.

PROCEDURE

CHECK DTC OUTPUT

Note

The freeze frame data is cleared when DTCs are cleared. Be sure to make a note of necessary data in advance.

Connect the GTS to the DLC3.
Turn the power switch on (IG).
Turn the GTS on.
Enter the following menus: Powertrain / FC / Trouble Codes.
Check for DTCs.

Powertrain > FC > Trouble Codes

Turn the power switch off.

Result

Proceed to
NEXT

CLEAR DTC

Connect the GTS to the DLC3.
Turn the power switch on (IG).
Turn the GTS on.
Enter the following menus: Powertrain / FC / Trouble Codes.
Clear the DTCs.

Powertrain > FC > Clear DTCs

Turn the power switch off and wait for 3 minutes or more.

Result

Proceed to
NEXT

CHECK HYDROGEN GAS LEAKAGE POINT

CAUTION:

Work procedures must be performed in an area with good ventilation (airflow) where hydrogen gas will not accumulate, and flames or other things that could act as ignition sources must not be present.
Accumulated hydrogen gas could ignite, resulting in a serious accident.
Open the hood with the power switch off, check for hydrogen leaks around the underbody and in the motor compartment with a hydrogen gas detector. If leakage is found, pay extra attention to fire safety in the following operations.

Turn the power switch off.
Remove the under cover.
Check that the hydrogen tank and hydrogen pipes are not damaged.

Check for a gas leaking sound, and then check if there are hydrogen leaks in the hydrogen pipes and components (high- and medium-range pressures area) with a hydrogen gas detector.

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*1	Hydrogen Inlet Receptacle Assembly	*2	High-range Hydrogen Pressure Pipe (for filling)
*3	Hydrogen Tank Tube Joint	*4	Hydrogen Tank Pressure Sensor (for Inlet Side)
*5	No. 1 Hydrogen Tank Assembly	*6	No. 2 Hydrogen Tank Assembly
*7	High-range Hydrogen Pressure Pipe (for feeding)	*8	Hydrogen Tank Pressure Sensor (for Outlet Side)
*9	Hydrogen Supply Regulator Assembly	*10	Medium-range Hydrogen Pressure Pipe
*11	FC Stack Assembly	*12	Hydrogen Injector
*a	High-range Pressure Area (when filling) (Hydrogen Inlet Receptacle Assembly → Hydrogen Tank Assembly )	*b	High-range Pressure Area (Hydrogen Tank Assembly → Hydrogen Supply Regulator Assembly)
*c	Medium-range Pressure Area (Hydrogen Supply Regulator Assembly → Hydrogen Injector)	*d	Low-range Pressure Area (Hydrogen Injector → FC Stack)

Standard value
300 ppm or less. (Hydrogen gas detector)

Result

Proceed to
OK
NG

CHECK HYDROGEN GAS LEAK Click here

CHECK DTC OUTPUT

Connect the GTS to the DLC3.
Turn the power switch on (READY) and wait for 2 minutes or more.
Turn the GTS on.
Enter the following menus: Powertrain / FC / Trouble Codes.

Check for DTCs.

Powertrain > FC > Trouble Codes

Result

Result	Proceed to
DTC P1E44-450 is output	A
DTCs are not output	B

Turn the power switch off.

CHECK FOR INTERMITTENT PROBLEMS Click here

CHECK EXHAUST HYDROGEN GAS

CAUTION:

Work procedures must be performed in an area with good ventilation (airflow) where hydrogen gas will not accumulate, and flames or other things that could act as ignition sources must not be present.
Accumulated hydrogen gas could ignite, resulting in a serious accident.

Ensure the safety of the areas in front and at the back of the vehicle.
Put wheel chocks and securely apply the parking brake.
Connect the GTS to the DLC3.
Turn the power switch on (IG).
Turn the GTS on.

Enter the following menus: Powertrain / FC / Data List / FC Mode, FC Intermittent Operation, Exhaust Drainage Valve Driving Request

Powertrain > FC > Data List

Tester Display
FC Mode
FC Intermittent Operation
Exhaust Drainage Valve Driving Request

*1 Tailpipe

*2 Hydrogen gas detector probe

Using a hydrogen gas detector, measure the hydrogen concentration in the gas emitted from the tail pipe.
Note
- Perform this measurement in an environment where there is no wind.
- Position the hydrogen gas detector probe in an area 100 mm (3.94 in.) away from the tailpipe opening. (Avoid locations underneath the tailpipe opening)
- Position the hydrogen gas detector probe so that it is free from dropping water that comes from the tailpipe opening.
Measure the hydrogen concentration for 1 minute with the shift lever in P, the power switch on (READY), the Data List "FC Mode" showing FC Working and "FC Intermittent Operation" showing OFF. Watch for changes in the concentration when the "Exhaust Drainage Valve Driving Request" is ON and OFF in the Data List.

Note

Start measurement immediately after the power switch is turned on (READY).

Turn the power switch off.

Result

Result	Proceed to
Hydrogen concentration increases when the "Exhaust Drainage Valve Driving Request" is ON but does not increase when it is OFF.*1	A
Other than above*2	B

*1: The exhaust drainage valve is normal

If the exhaust drainage valve is normal and P1E44-450 is output again, it can be determined that there is a hydrogen leak from the low-range pressure area inside the FC stack assembly, so replace the FC stack assembly.

*2: The exhaust drainage valve is malfunctioning
Exhaust drainage valve is stuck closed:

Regardless of the "Exhaust Drainage Valve Driving Request" being ON or OFF, the concentration shown on the hydrogen gas detector has remained low.

Exhaust drainage valve is stuck open:

Regardless of the "Exhaust Drainage Valve Driving Request" being ON or OFF, the concentration shown on the hydrogen gas detector has remained high when the power switch is on (READY).

REPLACE FC STACK ASSEMBLY Click here

CHECK HYDROGEN GAS LEAK

CAUTION:

Work procedures must be performed in an area with good ventilation (airflow) where hydrogen gas will not accumulate, and flames or other things that could act as ignition sources must not be present.
Accumulated hydrogen gas could ignite, resulting in a serious accident.

Apply soapy water to locate hydrogen leaking areas.

Note

Do not apply soapy water to the FC stack assembly.

Result

Proceed to
NEXT

REPLACE MALFUNCTIONING PARTS

*1	Tailpipe
*2	Hydrogen gas detector probe