check engine light YAMAHA NMAX 155 2021 Owners Manual

Table of contentsSafety information ............................ 1-1
Further safe-riding points ............... 1-5
Description ....................................... 2-1
Left view ......................................... 2-1
Right view ....................................... 2-2
Controls and instruments ............... 2-3
Smart key system ........................... 3-1
Smart key system ........................... 3-1
Operating range of the smart key system .................................. 3-2
Handling of the smart key and mechanical keys ......................... 3-3
Smart key ....................................... 3-4
Replacing the smart key battery..... 3-6
Main switch .................................... 3-7
Stop an d Start System ..................... 4-1
Stop and Start System ................... 4-1
Stop and Start System operation ... 4-1
Special features .............................. 5-1
CCU (Communication Control Unit) ................................ 5-1
Instrument an d control functions ... 6-1
Indicator lights and warning lights............................................ 6-1
Multi-function meter unit ................ 6-3
Handlebar switches ...................... 6-10 Front brake lever ........................... 6-11
Rear brake lever ............................ 6-11
ABS ............................................... 6-12
Traction control system ................ 6-13
Fuel tank cap ................................ 6-14
Fuel ............................................... 6-15
Fuel tank overflow hose ................ 6-17
Catalytic converter ........................ 6-17
Seat ............................................... 6-17
Helmet holders .............................. 6-18
Storage compartments ................. 6-19
Adjusting the shock absorber
assemblies ................................. 6-20
Power outlet ................................. 6-21
Sidestand ...................................... 6-22
Ignition circuit cut-off system ....... 6-22
For your safety – pre-operation
checks ............................................... 7-1
Operation an d important ri din g
points ................................................. 8-1
Engine break-in ............................... 8-1
Starting the engine .......................... 8-2
Starting off ...................................... 8-2
Acceleration and deceleration ........ 8-3
Braking ............................................ 8-3
Tips for reducing fuel consumption ................................ 8-3
Parking ........................................... 8-4 Perio
dic maintenance an d
a d justment ........................................ 9-1
Tool kit ............................................ 9-1
Periodic maintenance chart for the emission control system ....... 9-2
General maintenance and lubrication chart .......................... 9-3
Removing and installing panels ...... 9-7
Checking the spark plug................. 9-9
Canister ........................................ 9-11
Engine oil and oil strainer ............. 9-11
Why Yamalube.............................. 9-13
Final transmission oil .................... 9-13
Coolant ......................................... 9-15
Air filter and V-belt case
air filter elements ....................... 9-16
Checking the throttle grip
free play..................................... 9-19
Valve clearance............................. 9-19
Tires .............................................. 9-19
Cast wheels .................................. 9-21
Checking the front and rear brake lever free play .................. 9-21
Checking the front and rear brake pads ................................ 9-22
Checking the brake fluid level ...... 9-23
Changing the brake fluid .............. 9-24
Checking the V-belt ...................... 9-24
Checking and lubricating the
cables ........................................ 9-25UBBDE0E0.book Page 1 Wednesday, June 2, 2021 2:57 PM

Stop and Start System
4-1
4
EAU76825
Stop an d Start SystemThe Stop and Start System stops the
engine automatically when the vehicle
is stopped in order to prevent noise,
control exhaust emissions, and reduce
fuel consumption.
When the rider turns the throttle grip
slightly, the engine restarts automati-
cally and the vehicle starts off.NOTICE
ECA23961
When parkin g the vehicle or leavin g
the vehicle unatten ded , be sure to
turn the main switch off. If the Stop
an d Start System is left turne d on,
the battery could become dis- char
ged an d it may not be possi ble
to restart the en gine due to insuffi-
cient battery volta ge.
TIP Although the engine normally
stops at the same time as the ve-
hicle, there may be a delay when
operating the vehicle under 10
km/h, such as in heavy traffic.
 If you think the battery voltage is
low because the engine cannot be
started using the starter switch or
for some other reason, do not turn
on the Stop and Start System.
 Have a Yamaha dealer check the
battery at the intervals specified in
the periodic maintenance chart.
EAU76671
Stop an d Start System opera-
tion
EAU76687
Activatin g the Stop an d Start Sys-
tem 1. Turn the main switch on.
2. Set the Stop and Start System switch to “ ”.
1. Stop and Start System indicator light “ ”
1
ON
A
AAA
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Stop and Start System
4-2
4 3. The Stop and Start System acti-
vates and the indicator light
comes on when the following con-
ditions are met: The Stop and Start System
switch is set to “ ”.
 After the engine was warmed
up, the engine was left idling
for a certain period.
 The vehicle has traveled at a
speed of 10 km/h or higher.
4. To turn off the Stop and Start Sys- tem, set the Stop and Start Sys-
tem switch to “ ”.
TIPTo preserve battery power, the
Stop and Start System may not
activate.
 If the Stop and Start System does
not activate, have a Yamaha deal-
er check the battery.
EAU76832
Stop the en gine
The engine will stop automatically
when the following conditions are met:  The Stop and Start System switch
is set to “ ”.
 The “ ” indicator light on the
multi-function meter is on.
 The vehicle is stopped with the
throttle grip fully returned. At this time, the “ ” indicator light
starts flashing to indicate that the en-
gine is currently stopped by the Stop
and Start System.
EAU76704
Restart the en
gine
If the throttle grip is turned while the
Stop and Start System indicator light is
flashing, the engine will automatically
restart and the “ ” indicator light will
stop flashing.
1. On
A1
A
AAA
A
A
1. On
2. Flashing
A
1
2
A
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Instrument and control functions
6-1
6
EAU77123
In dicator lig hts and warning
lig hts
EAU88900
Turn si gnal in dicator li ghts “ ”
an d“”
Each indicator light will flash when its
corresponding turn signal lights are
flashing.
EAU88910
Hi gh beam in dicator li ght “ ”
This indicator light comes on when the
high beam of the headlight is switched
on.
EAU88712
Malfunction in dicator li ght
(MIL) “ ”
This light comes on or flashes if a prob-
lem is detected in the engine or other
vehicle control system. If this occurs,
have a Yamaha dealer check the on-
board diagnostic system. The electri-
cal circuit of the warning light can be
checked by turning the vehicle power
on. The light should come on for a few
seconds, and then go off. If the light
does not come on initially when the ve-
hicle power is turned on, or if the light
remains on, have a Yamaha dealer
check the vehicle.
NOTICE
ECA26820
If the MIL starts flashin g, re duce en-
g ine spee d to prevent exhaust sys-
tem damag e.TIPThe engine is sensitively monitored by
the on-board diagnostic system to de-
tect deterioration and malfunction of
the emission control system. Therefore
the MIL may come on or flash due to
vehicle modifications, lack of mainte-
nance, or excessive/improper use of
the vehicle. To prevent this, observe
these precautions.
 Do not attempt to modify the soft-
ware of the engine control unit.
 Do not add any electrical acces-
sories that interfere with engine
control.
 Do not use aftermarket accesso-
ries or parts such as suspension,
spark plugs, injectors, exhaust
system, etc.
 Do not change the drivetrain
specifications (chain, sprockets,
wheels, tires, etc.).
1. Left turn signal indicator light “ ”
2. Incoming notification indicator light “ ”
3. Traction control system indicator
light “ ”
4. ABS warning light “ ”
5. High beam indicator light “ ”
6. Malfunction indicator light “ ”
7. Stop and Start System indicator light “ ”
8. Smart key system indicator light “ ”
9. Incoming call indicator light “ ”
10.Right turn signal indicator light “ ”
4
110
5
6
7
8
23 9
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Instrument and control functions
6-2
6 
Do not remove or alter the O2 sen-
sor, air induction system, or ex-
haust parts (catalysts or EXUP,
etc.).
 Maintain V-belt and drive belt (if
equipped) properly.
 Maintain correct tire pressure.
 Do not operate the vehicle in an
extreme manner. For example, re-
peated or excessive opening and
closing of the throttle, racing,
burnouts, wheelies, etc.
EAU88890
ABS warnin g li ght “ ”
This warning light comes on when the
vehicle is first turned on, and goes off
after starting riding. If the warning light
comes on while riding, the anti-lock
brake system may not work correctly.
WARNING
EWA16043
If the ABS warnin g lig ht does not
turn off after reachin g 10 km/h (6
mi/h), or if the warnin g li ght comes
on while ri din g:
 Use extra caution to avoi d pos-
si ble wheel lock d uring emer-
g ency brakin g. 
Have a Yamaha dealer check
the vehicle as soon as possib le.
TIPThe ABS warning light may come on
while revving the engine with the vehi-
cle on its centerstand, but this does
not indicate a malfunction.
EAU88930
Traction control system indicator
li g ht “ ”
This indicator light will flash when trac-
tion control has engaged.
If the traction control system is turned
off, this indicator light will come on.
(See page 6-13.)TIPWhen the vehicle is turned on, the light
should come on for a few seconds and
then go off. If the light does not come
on, or if the light remains on, have a
Yamaha dealer check vehicle.
EAUN2770
Smart key system in dicator
li g ht “ ”
This indicator light communicates the
status of the smart key system. When
the smart key system is operating nor-
mally, this indicator light will be off. If
there is an error in the smart key sys-
tem, the indicator light will flash. The
indicator light will also flash when com-
munication between the vehicle and
smart key takes place and when cer-
tain smart key system operations are
carried out.
EAUN2830
Stop an d Start System in dicator
li g ht “ ”
This indicator light comes on when the
Stop and Start System activates. The
indicator light will flash when the en-
gine is automatically stopped by the
Stop and Start System.TIPEven if the Stop and Start Switch is set
to Ž, this indicator light may not
come on. (See page 4-1.)
A
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Instrument and control functions
6-14
6 Resetting
the traction control sys-
tem
The traction control system will auto-
matically disable under certain condi-
tions; such as when a sensor fault is
detected, or when only one wheel is al-
lowed to rotate for more than a few
seconds. Should this happen,
the “ ” indicator light will come on,
and possibly the “ ” warning light,
too.
TIPWhen the vehicle is on the centerstand,
do not rev the engine for an extended
period of time. Otherwise, the traction
control system will automatically dis-
able and need to be reset.If the traction control system automat-
ically disables, try resetting it as fol-
lows. 1. Stop the vehicle and turn it off completely.
2. Wait a few seconds and then turn the vehicle power on.
3. The Ž indicator light should turn off and the system be en-
abled.TIPIf the Ž indicator light remains on
after resetting, the vehicle may still be
ridden; however, have a Yamaha deal-
er check the vehicle as soon as possi-
ble.4. Have a Yamaha dealer check thevehicle and turn off the Ž
warning light.
EAUN2571
Fuel tank capTo open the fuel tank cap lid, turn the
main switch to “OPEN” position and
push the “FUEL” button.
To open the the fuel tank cap, turn it
counterclockwise and pull it off.
1. Traction control system indicator light “ ”
2. Engine trouble warning light “ ”
1
2
1. “FUEL” button
1. Fuel tank cap lid
2. Fuel tank cap
1
1
2
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Operation and important ri din g points
8-2
8
EAU86741
Startin g the en gineThe ignition circuit cut-off system will
enable starting only when the side-
stand is up.
To start the engine1. Turn the main switch on.
2. Confirm the indicator and warning light(s) come on for a few sec-
onds, and then go off. (See page
6-1.)TIPDo not start the engine if the en-
gine trouble warning light remains
on.
 The ABS warning light should
come on and stay on until the ve-
hicle reaches a speed of 10 km/h
(6 mi/h).NOTICE
ECA24110
If a warnin g or in dicator li ght does
not work as d escribed a bove, have a
Yamaha dealer check the vehicle.3. Close the throttle completely.
4. While applying the front or rear
brake, push the start switch. 5. Release the start switch when the
engine starts, or after 5 seconds.
Wait 10 seconds before pressing
the switch again to allow battery
voltage to restore.
NOTICE
ECA11043
For maximum en gine life, never ac-
celerate har d when the en gine is
col d!
EAU45093
Startin g off1. While pulling the rear brake lever
with your left hand and holding the
grab bar with your right hand,
push the scooter off the center-
stand.
2. Sit astride the seat, and then ad- just the rear view mirrors.
3. Switch the turn signals on.
4. Check for oncoming traffic, and then slowly turn the throttle grip
(on the right) in order to take off.
5. Switch the turn signals off.1. Grab bar
1
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Periodic maintenance an d a djustment
9-5
9
20 En gine oil • Change (warm engine before
draining).
• Check oil level and vehicle for oil leakage. At the initial interval and when the oil change indicator flashes or
comes on. 
21 *Engine oil strainer • Clean. 
22 *Final transmission
oil • Check vehicle for oil leakage.

• Change. 
23 *Coolin g system • Check coolant level and vehicle
for coolant leakage. 
• Change. Every 3 years
24 *V-belt • Replace. When the V-belt replacement indicator flashes or comes on
25 *Front an
d rear
b rake switches • Check operation.

26 *Movin
g parts an d
cab les • Lubricate.

27 *Throttle
grip hous-
in g an d cab le • Check operation and free play.
• Adjust the throttle cable free play
if necessary.
• Lubricate the throttle grip housing and cable. 
28 *Li
ghts, si gnals an d
switches • Check operation.
• Adjust headlight beam.

NO. ITEM CHECK OR MAINTENANCE JOB
ODOMETER READING
ANNUAL
CHECK
1000 km
(600 mi) 6000 km
(3500 mi) 12000 km
(7000 mi) 1
8000 km

(10500 mi) 24000 km
(14000 mi)
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Periodic maintenance an d a djustment
9-9
9 2. Install the windshield by installing
the screws.
EAU67161
Checkin g the spark plu gThe spark plug is an important engine
component, which is easy to check.
Since heat and deposits will cause any
spark plug to slowly erode, the spark
plug should be removed and checked
in accordance with the periodic main-
tenance and lubrication chart. In addi-
tion, the condition of the spark plug
can reveal the condition of the engine.
To remove the spark plu g
1. Place the vehicle on the center- stand.
2. Remove panels A and B. (See page 9-7.)
3. Remove the spark plug cap. 4. Remove the spark plug as shown,
with the spark plug wrench includ-
ed in the owner’s tool kit.
To check the spark plu g
1. Check that the porcelain insulator around the center electrode of the
spark plug is a medium-to-light
tan (the ideal color when the vehi-
cle is ridden normally).
TIPIf the spark plug shows a distinctly dif-
ferent color, the engine could be oper-
ating improperly. Do not attempt to
diagnose such problems yourself. In-
stead, have a Yamaha dealer check
the vehicle.
1. Spark plug cap
1
1. Spark plug wrench
1
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Periodic maintenance an d a djustment
9-11
9
EAU36113
CanisterThis model is equipped with a canister
to prevent the discharging of fuel vapor
into the atmosphere. Before operating
this vehicle, make sure to check the
following:
 Check each hose connection.
 Check each hose and canister for
cracks or damage. Replace if
damaged.
 Make sure that the canister
breather is not blocked, and if
necessary, clean it.
EAU66995
Engine oil an d oil strainerThe engine oil level should be checked
before each ride. In addition, the oil
must be changed and the oil strainer
cleaned at the intervals specified in the
periodic maintenance and lubrication
chart.
To check the en gine oil level
1. Place the vehicle on the center- stand. A slight tilt to the side can
result in a false reading.
2. Start the engine, warm it up for several minutes, and then turn it
off.
3. Wait a few minutes until the oil set- tles, remove the engine oil filler
cap, wipe the engine oil dipstick
clean, insert it back into the oil fill-
er hole (without screwing it in), and
then remove it again to check the
oil level. WARNING! The muffler
an d muffler protector become
very hot d uring use. To avoi d
possi ble burns, let the muffler
an d protector cool before re-
movin g the oil filler cap.
[EWA17810]
TIPThe engine oil should be between the
tip of the dipstick and the maximum
level mark.4. If the engine oil is not between the
tip of the dipstick and the maxi-
mum level mark, add sufficient oil
of the recommended type to raise
it to the correct level.
5. Insert the dipstick into the oil filler hole, and then tighten the oil filler
cap.
1. Canister
2. Canister breather
2
1
1. Oil filler hole
2. O-ring
3. Engine oil dipstick
4. Maximum level mark
5. Tip of the engine oil dipstick
3245
1
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