2021 FORD MUSTANG check engine

On-Board Diagnostics (OBD-II)
Your vehicle has a computer known as the
on-board diagnostics system (OBD-II) that
monitors the engine
’s emission control
system. The system protects the
environment by making sure that your
vehicle continues to meet government
emission standards. The OBD-II system
also assists a service technician in properly
servicing your vehicle. When the service engine soon
indicator illuminates, the OBD-II
system has detected a
malfunction. Temporary malfunctions may
cause the service engine soon indicator to
illuminate. Examples are:
1. Your vehicle has run out of fuel —the
engine may misfire or run poorly.
2. Poor fuel quality or water in the fuel —the engine may misfire or run
poorly.
3. The fuel fill inlet may not have closed properly. See Refueling (page 156).
4. Driving through deep water —the
electrical system may be wet.
You can correct these temporary
malfunctions by filling the fuel tank with
good quality fuel, properly closing the fuel
fill inlet or letting the electrical system dry
out. After three driving cycles without these
or any other temporary malfunctions
present, the service engine soon indicator
should stay off the next time you start the
engine. A driving cycle consists of a cold
engine startup followed by mixed city and
highway driving. No additional vehicle
service is required. If the service engine soon indicator remains
on, have your vehicle serviced at the first
available opportunity. Although some
malfunctions detected by the OBD-II may
not have symptoms that are apparent,
continued driving with the service engine
soon indicator on can result in increased
emissions, lower fuel economy, reduced
engine and transmission smoothness and
lead to more costly repairs.
Readiness for Inspection and
Maintenance (I/M) Testing
Some state and provincial and local
governments may have
Inspection/Maintenance (I/M) programs
to inspect the emission control equipment
on your vehicle. Failure to pass this
inspection could prevent you from getting
a vehicle registration.
If the service engine soon
indicator is on or the bulb does
not work, your vehicle may need
service. See On-Board Diagnostics.
Your vehicle may not pass the I/M test if
the service engine soon indicator is on or
not working properly (bulb is burned out),
or if the OBD-II system has determined
that some of the emission control systems
have not been properly checked. In this
case, the vehicle is not ready for I/M
testing.
If the vehicle ’s engine or transmission has
just been serviced, or the battery has
recently run down or been replaced, the
OBD-II system may indicate that the
vehicle is not ready for I/M testing. To
determine if the vehicle is ready for I/M
testing, turn the ignition key to the on
position for 15 seconds without cranking
the engine. If the service engine soon
indicator blinks eight times, it means that
the vehicle is not ready for I/M testing; if
the service engine soon indicator stays on
solid, it means that your vehicle is ready
for I/M testing.
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Mustang (CZG) Canada/United States of America, Vehicles Built From: 14-09-2020, enUSA, Edition date: 202010, Second-Printing Engine Emission Control

The OBD-II system checks the emission
control system during normal driving. A
complete check may take several days.
If the vehicle is not ready for I/M testing,
you can perform the following driving cycle
consisting of mixed city and highway
driving:
1. 15 minutes of steady driving on an
expressway or highway followed by 20
minutes of stop-and-go driving with at
least four 30-second idle periods.
2. Allow your vehicle to sit for at least eight hours with the ignition off. Then,
start the vehicle and complete the
above driving cycle. The vehicle must
warm up to its normal operating
temperature. Once started, do not turn
off the vehicle until the above driving
cycle is complete.
If the vehicle is still not ready for I/M
testing, you need to repeat the above
driving cycle.
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Mustang (CZG) Canada/United States of America, Vehicles Built From: 14-09-2020, enUSA, Edition date: 202010, Second-Printing Engine Emission Control

In sport (S) mode, SelectShift does not
automatically upshift, even if the engine is
approaching the RPM limit.
Pull the + paddle on the steering wheel
to activate SelectShift.
•
Pull the right paddle (+) to upshift.
• Pull the left paddle (–) to downshift. SelectShift in drive (D):
•
Provides a temporary manual mode
for performing more demanding
maneuvers where you require extra
control of gear selection, for example,
when towing or overtaking. This mode
holds a selected gear for a temporary
period of time dependent on driver
inputs, for example, steering or
accelerator pedal input.
SelectShift in sport (S):
• Provides a permanent manual gear
selection where you require full control
of gear selection.
To exit SelectShift mode shift the
transmission into another gear, for
example, drive (D), or hold the (+) paddle
for 2 seconds.
The instrument cluster displays your
currently selected gear. If a gear you
request is not available due to vehicle
conditions, the current gear flashes two
times. Brake-Shift Interlock WARNING: Do not drive your
vehicle until you verify that the
stoplamps are working. WARNING:
When doing this
procedure, you need to take the
transmission out of park (P) which
means your vehicle can roll freely. To
avoid unwanted vehicle movement,
always fully apply the parking brake prior
to doing this procedure. Use wheels
chocks if appropriate. WARNING:
If the parking brake is
fully released, but the brake warning
lamp remains illuminated, the brakes
may not be working properly. Have your
vehicle checked as soon as possible.
Use the brake shift interlock lever to move
the gearshift lever from the park position
in the event of an electrical malfunction or
if your vehicle has a dead battery.
Apply the parking brake and switch the
ignition off before performing this
procedure. 1.
Using a flat head screwdriver or similar
tool, remove the chrome bezel and
gearshift bracket at the base of the
gearshift lever.
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Mustang (CZG) Canada/United States of America, Vehicles Built From: 14-09-2020, enUSA, Edition date: 202010, Second-Printing TransmissionE144821 E184747

GENERAL INFORMATION
Note:
Occasional brake noise is normal. If
a metal-to-metal, continuous grinding or
continuous squeal sound is present, the
brake linings may be worn-out and an
authorized dealer should check them. If the
vehicle has continuous vibration or shudder
in the steering wheel while braking, an
authorized dealer should check your vehicle.
Note: Brake dust may accumulate on the
wheels, even under normal driving
conditions. Some dust is inevitable as the
brakes wear and does not contribute to
brake noise. See Cleaning the Wheels
(page 296).
Wet brakes result in reduced braking
efficiency. Gently press the brake pedal a
few times when driving from a car wash or
standing water to dry the brakes.
Brake Over Accelerator
In the event the accelerator pedal
becomes stuck or entrapped, apply steady
and firm pressure to the brake pedal to
slow the vehicle and reduce engine power.
If you experience this condition, apply the
brakes and bring your vehicle to a safe
stop. Move the transmission to park (P),
switch the engine off and apply the parking
brake. Inspect the accelerator pedal for
any interference. If none are found and the
condition persists, have your vehicle towed
to the nearest authorized dealer.
Emergency Brake Assist
Emergency brake assist detects when you
brake heavily by measuring the rate at
which you press the brake pedal. It
provides maximum braking efficiency as
long as you press the pedal. Emergency
brake assist can reduce stopping distances
in critical situations. Note:
Depending on applicable laws and
regulations in the country for which your
vehicle was originally built, your brake lamps
could flash during heavy braking. Following
this, your hazard lights may also flash when
your vehicle comes to a stop.
Anti-lock Brake System
This system helps you maintain steering
control during emergency stops by keeping
the brakes from locking. This lamp momentarily
illuminates when you switch the
ignition on. If the light does not
illuminate during start up, remains on or
flashes, the anti-lock braking system may
be disabled. Have the system checked by
an authorized dealer. If the anti-lock brake
system is disabled, normal braking is still
effective.
See
Warning Lamps and Indicators
(page 94).
Note: Indicators vary depending on region. This lamp also illuminates
momentarily when you switch
the ignition on to confirm the
lamp is functional. If it does not
illuminate when you switch the
ignition on, or begins to flash at
any time, have the system checked by an
authorized dealer. If the brake warning
lamp illuminates with the parking brake
released, have the system checked
immediately.
HINTS ON DRIVING WITH
ANTI-LOCK BRAKES
The anti-lock brake system does not
eliminate the risks when:
• You drive too closely to the vehicle in
front of you.
• Your vehicle is hydroplaning.
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Mustang (CZG) Canada/United States of America, Vehicles Built From: 14-09-2020, enUSA, Edition date: 202010, Second-Printing Brakes E270480

•
You take corners too fast.
• The road surface is poor.
Note: If the system activates, the brake
pedal could pulse and may travel further.
Maintain pressure on the brake pedal. You
may also hear a noise from the system. This
is normal.
PARKING BRAKE
Vehicles With Automatic
Transmission WARNING: Always set the parking
brake and leave your vehicle with the
transmission in park (P).
Note: If you park your vehicle on a hill and
facing uphill, shift into park (P) and turn the
steering wheel away from the curb.
Note: If you park your vehicle on a hill and
facing downhill, shift into park (P) and turn
the steering wheel toward the curb.
Vehicles with Manual
Transmission WARNING:
Always set the parking
brake fully and make sure you shift the
gearshift lever to first gear. Switch the
ignition off and remove the key whenever
you leave your vehicle.
Note: If you park your vehicle on a hill and
facing uphill, select first gear and turn the
steering wheel away from the curb.
Note: If you park your vehicle on a hill and
facing downhill, select reverse gear and turn
the steering wheel toward the curb.
To park your vehicle:
1. Apply the brake and shift into the neutral position. 2. Fully apply the parking brake, hold the
clutch pedal down, then shift into first
(1).
3. Turn the ignition off.
After you turn the engine off you can now
release the clutch pedal.
All Vehicles WARNING:
If the parking brake is
fully released, but the brake warning
lamp remains illuminated, the brakes
may not be working properly. Have your
vehicle checked as soon as possible. To set the parking brake, pull the parking
brake handle up as far as possible.
To release the parking brake:
1. Press and hold the button at the end
of the parking brake handle.
2. Pull the handle up slightly, then push the handle down.
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Mustang (CZG) Canada/United States of America, Vehicles Built From: 14-09-2020, enUSA, Edition date: 202010, Second-Printing BrakesE223664

To create or save MyMode, press the
button on the steering wheel and access
the menu. See General Information
(page 99). The available systems display.
Choose your desired settings using the
appropriate buttons and menus. Press and
hold OK to save your settings. MyMode is
added to the drive mode list and can be
selected the next time you drive your
vehicle.
Note: The system has diagnostic checks
that continuously monitor the system to
make sure it properly operates. If a mode is
unavailable due to a system fault or change
in gear position, the selected mode defaults
to normal.
Note: Pre-Collision Assist is automatically
disabled when track mode is selected.
See
Pre-Collision Assist (page 202).
Note: If your vehicle has adaptive dampers,
the steering setting is optimized to work with
each drive mode. Other steering settings
may not be available.
Selectable Steering Press the steering button on the
instrument panel to change the
steering feel. The first press
illuminates the selected mode. Each time
you press the button, it changes the mode.
Modes:
• Normal - Default factory setting.
• Sport - Slightly higher effort required
for steering with more road force felt
through the steering wheel.
• Comfort - Slightly less effort required
for steering with less road force felt
through the steering wheel.
Note: A soft feedback bump in the steering
wheel may be felt after you make a
selection. Note:
The steering setting defaults to
normal if the battery is disconnected or
removed.
Active Exhaust
(If Equipped) Use the information display to
adjust the tone of the exhaust.
Active Exhaust modes:
• Quiet - Lowers the noise of the exhaust.
• Normal - Default factory setting.
• Sport - Raises the noise of the exhaust.
• Track - Tunes the exhaust for track
performance.
Note: The track exhaust mode setting is
only for use at tracks and not for use on
public roadways. Use of this setting results
in increased exterior noise, which may not
meet state and local laws and regulations.
It is the obligation of the driver to operate
the vehicle in a manner that complies with
state and local requirements. Only use the
track exhaust mode setting at a competition
track or an off-road course where elevated
exterior vehicle noise is acceptable.
Rev Match
(If Equipped)
This feature provides a smoother driving
experience, particularly during a downshift
event. This is accomplished by a shift
position prediction that commands a quick
engine RPM match to the selected gear.
You can switch this feature on and off
through the information display. See
General Information
(page 99).
Note: The system remembers your last
selection through ignition cycles.
Note: Rev match is only available with a
manual transmission.
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Mustang (CZG) Canada/United States of America, Vehicles Built From: 14-09-2020, enUSA, Edition date: 202010, Second-Printing Driving AidsE174705 E287122

When Towing a Trailer
•
Do not drive faster than 70 mph
(113 km/h) during the first 500 mi
(800 km).
• Do not make full-throttle starts.
• Check your hitch, electrical connections
and trailer wheel lug nuts thoroughly
after you have traveled 50 mi (80 km).
• When stopped in congested or heavy
traffic during hot weather, place the
transmission in park (P) or neutral (N)
to aid engine and transmission cooling
and to help air conditioning
performance.
• Switch off the speed control with
heavy loads or in hilly terrain. The
speed control may turn off
automatically when you are towing on
long, steep grades.
• Shift to a lower gear when driving down
a long or steep hill. Do not apply the
brakes continuously, as they may
overheat and become less effective.
• If your transmission is equipped with a
Grade Assist or Tow/Haul feature, use
this feature when towing. This provides
engine braking and helps eliminate
excessive transmission shifting for
optimum fuel economy and
transmission cooling.
• Allow more distance for stopping with
a trailer attached. Anticipate stops and
brake gradually.
• Avoid parking on a slope. However, if
you must park on a slope:
1. Turn the steering wheel to point your vehicle tires away from traffic flow.
2. Set your vehicle parking brake.
3. Place the automatic transmission in park (P) or manual transmission in a
low gear. 4. Place wheel chocks in front and back
of the trailer wheels. Chocks are not
included with your vehicle.
Launching or Retrieving a Boat or
Personal Watercraft (PWC)
Note: Disconnect the wiring to the trailer
before
backing the trailer into the water.
Note: Reconnect the wiring to the trailer
after
removing the trailer from the water.
When backing down a ramp during boat
launching or retrieval:
• Do not allow the static water level to
rise above the bottom edge of the rear
bumper.
• Do not allow waves to break higher
than
6 in (15 cm) above the bottom
edge of the rear bumper.
Exceeding these limits may allow water to
enter vehicle components:
• Causing internal damage to the
components.
• Affecting driveability, emissions, and
reliability.
Any time the rear axle submerges in water,
replace the rear axle lubricant. Water may
contaminate the rear axle lubricant, which
is not a normal maintenance inspection
item unless there is a possibility of a leak
or other axle repair is required.
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Mustang (CZG) Canada/United States of America, Vehicles Built From: 14-09-2020, enUSA, Edition date: 202010, Second-Printing Towing

REDUCED ENGINE
PERFORMANCE
WARNING: If you continue to drive
your vehicle when the engine is
overheating, the engine could stop
without warning. Failure to follow this
instruction could result in the loss of
control of your vehicle.
If the engine coolant temperature gauge
needle moves to the upper limit position,
the engine is overheating. See Gauges
(page 90).
You must only drive your vehicle for a short
distance if the engine overheats. The
distance you can travel depends on
ambient temperature, vehicle load and
terrain. The engine continues to operate
with limited power for a short period of
time.
If the engine temperature continues to rise,
the fuel supply to the engine reduces. The
air conditioning switches off and the engine
cooling fan operates continually.
1. Gradually reduce your speed and stop your vehicle as soon as it is safe to do
so.
2. Immediately switch the engine off to prevent severe engine damage.
3. Wait for the engine to cool down.
4. Check the coolant level. See
Engine
Coolant Check (page 264).
5. Have your vehicle checked as soon as possible. Reduced Vehicle Top Speed
Your vehicle's ability to reach and maintain
top speed is partially dependent upon
ambient temperature. Under certain
environmental conditions, your vehicle's
top speed may be reduced to protect
powertrain components.
ECONOMICAL DRIVING
Fuel economy is affected by several things
such as how you drive, the conditions you
drive under and how you maintain your
vehicle.
There are some things to keep in mind that
may improve your fuel economy:
•
Accelerate and slow down in a smooth,
moderate fashion.
• Drive at steady speeds.
• Anticipate stops; slowing down may
eliminate the need to stop.
• Combine errands and minimize
stop-and-go driving (When running
errands, go to the furthest destination
first and then work your way back
home).
• Close the windows for high-speed
driving.
• Drive at reasonable speeds.
• Keep the tires properly inflated and use
only the recommended size.
• Use the recommended engine oil.
• Perform all regularly scheduled
maintenance.
There are also some things you may want
to avoid doing because they reduce your
fuel economy:
• Avoid sudden or hard accelerations.
• Avoid revving the engine before turning
off the car.
• Avoid long idle periods.
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Mustang (CZG) Canada/United States of America, Vehicles Built From: 14-09-2020, enUSA, Edition date: 202010, Second-Printing Driving Hints