MODEL

Mirai

MODEL YEAR

2016 – 2019

PREVIOUS

NEW

898A36201300
898A36202200
898A36202300
898A36202400
898A36202500
898A36202600
898A36202700

898A36202800

Repair Procedure

1. Using Techstream, check for the following stored DTC.
P1DEF – 450 FC Stack Performance.
Is the DTC present?


YES — Continue to step 2.



NO — This bulletin does NOT apply. Continue diagnosis using the applicable
Repair Manual.

2. Perform a stimulation test.
A. Connect Techstream to the DLC3.
B. Turn the power switch ON (READY).
C. Let the vehicle warm up for 5 minutes.
D. Turn Techstream ON.
(1) Enter the following menus: Powertrain – FC – Data List – All Data
E. Turn the vehicle OFF, then IG-ON.
F. Push the H2O button.
G. Confirm the H2O light is on.
H. Ready ON the vehicle.

© 2022 Toyota Motor Sales, USA

T-SB-0046-22

May 5, 2022

Page 5 of 8

MIL ON DTC P1DEF - Fuel Cell Performance
Repair Procedure (continued)

I.

Confirm the Ready light is ON, and then Ready OFF. The active drain water procedure
will begin.

J. The H2O light will turn OFF when the active drain water procedure is completed.
NOTE
This procedure will take approximately 10 minutes.

K. Drive the vehicle for 10 minutes.
CAUTION
When performing the confirmation driving pattern, obey ALL speed limits and
traffic laws.

L. Stop the vehicle in a safe location.
M. Record a snapshot of the Data List.
Perform one of the following steps to achieve maximum power output and record the
maximum values of FC Current, FC Voltage Before Boosting, and FC Stack Cell
Minimum Voltage.
STEP No.

1

STIMULATION TEST PROCEDURE

A. From idle, press the accelerator pedal to 100% and hold
for 4 seconds.

MEASURE OF
SPEED REACHED

49.7 mph (80 km/h)

B. Stop the vehicle in a safe location and place the vehicle in
P range.
A. In P range, press the accelerator pedal to 100% and wait for
a beep. Keep the accelerator depressed for 4 seconds.

2

B. Release the accelerator pedal.

28 mph (45 km/h)

C. Change range to D, press the accelerator pedal to 100%,
and hold for 2 seconds
A. Operate the vehicle at a speed of 25 mph.
3

4

B. From 25 mph, press the accelerator pedal to 100% and
increase speed to 37 mph.
C. Decrease speed back to 25 mph.

37.3 mph (60 km/h)

D. Repeat steps B and C three times.
A. Make sure the vehicle is stopped.
B. From idle, press the accelerator pedal to reach 100% in
approximately 3 seconds.

28 mph (45 km/h)

© 2022 Toyota Motor Sales, USA

T-SB-0046-22

May 5, 2022

Page 6 of 8

MIL ON DTC P1DEF - Fuel Cell Performance
Repair Procedure (continued)

3. Check Techstream snapshot data – FC Current (maximum value).
Is FC Current above 400A?


YES — Continue to step 4.



NO — The stimulation test MUST be performed until 400A or more is achieved.

4. Using the FC Current MAX value, check Techstream snapshot data – FC Voltage Before
Boosting and FC Stack Cell Minimum Voltage.
Calculate
V = (FC Voltage Before Boosting ÷ 370) – FC Stack Cell Minimum Voltage.
V
Example

Is

=

41.64mV

FC VOLTAGE
BEFORE BOOSTING

÷

370

–

FC STACK CELL
MINIMUM VOLTAGE

222.6

0.56

V less than 110 mV?



YES — Go to step 7.



NO — Continue to step 5.

5. Check Techstream snapshot data – FC Stack Cell Minimum Voltage Cell Channel No.
Is the channel between 186ch and 195ch?


YES — Continue to step 6.



NO — Perform the stimulation test again.

6. Replace the fuel cell stack.
NOTICE
BEFORE replacing the fuel cell stack, ensure that a code compliant facility for hydrogen
repair has been approved with the local Authority Having Jurisdiction (AHJ). This repair
MUST be performed in a code compliant facility.

Refer to TIS, applicable model and model year Repair Manual:


2016 / 2017 / 2018 / 2019 Mirai:
Engine/Hybrid System – Fuel System – “FC Control: FC Stack: Removal”



2016 / 2017 / 2018 / 2019 Mirai:
Engine/Hybrid System – Fuel System – “FC Control: FC Stack: Installation”

© 2022 Toyota Motor Sales, USA

T-SB-0046-22

May 5, 2022

Page 7 of 8

MIL ON DTC P1DEF - Fuel Cell Performance
Repair Procedure (continued)

7. Check for the Authorized Modifications Label affixed to the vehicle in the location shown
below. Confirm if the FCM calibration has been updated.
Is the calibration ID listed the latest FCM calibration?


YES — This bulletin does NOT apply. Continue diagnosis using the applicable
Repair Manual.



NO — Continue to step 8.

Figure 1. Location of Authorized Modifications Label for 2016 – 2019 Mirai

TOYOTA MOTOR CORPORATION
AUTHORIZED MODIFICATIONS
THE FOLLOWING MODIFICATIONS HAVE BEEN MADE:
1
2

THESE MODIFICATIONS HAVE BEEN APPROVED
AS APPROPRIATE BY EPA AND CARB
3

DEALER CODE:
CHANGE AUTHORITY:

4

DATE:

5

1

Replacement FCM Part Number
(i.e., 898A1-62026)

4

Date Completed

2

New Calibration ID (i.e., 898A36202800)

5

This SB Number

3

Dealer Code

© 2022 Toyota Motor Sales, USA

T-SB-0046-22

May 5, 2022

Page 8 of 8

MIL ON DTC P1DEF - Fuel Cell Performance
Repair Procedure (continued)

8. Flash reprogram the FCM.
NOTE
 The battery diagnostic tool MUST be used in Power Supply Mode to maintain
battery voltage at 13.5V while flash reprogramming the vehicle.
 For details on how to use the battery diagnostic tool, refer to the DCA-8000 Instruction Manual
located on TIS – Diagnostics – Tools & Equipment – Battery Diagnostics.

Follow the procedures outlined in T-SB-0134-16, Techstream ECU Flash Reprogramming
Procedure, and flash the FCM with the NEW calibration file update.

9. Prepare and install the Authorized Modifications Label.
A. Using a permanent marker, enter the following information on the label:


FCM part number [Refer to the Parts Information section for the NEW
PART NUMBER]



Calibration ID(s) [Refer to the Calibration Information section for the
NEW CALIBRATION ID]
Dealer Code





Repair Date
Change Authority [This bulletin number]

B. Install the Authorized Modifications Label on the vehicle at the location shown in Figure 1.
The Authorized Modifications Label is available through the MDC, P/N 00451-00001-LBL.

10. Start the engine and warm it up to normal operating temperature.

11. Test-drive the vehicle to confirm proper vehicle operation.

© 2022 Toyota Motor Sales, USA