2021 CADILLAC CT4 check engine

Cadillac CT4 Owner Manual (GMNA-Localizing-U.S./Canada-14584335) -
2021 - CRC - 11/23/20
386 SERVICE AND MAINTENANCE
Maintenance Schedule
Additional Required Services -
Severe12 000 km/7,500 mi
24 000 km/15,000 mi
36 000 km/22,500 mi
48 000 km/30,000 mi
60 000 km/37,500 mi
72 000 km/45,000 mi
84 000 km/52,500 mi
96 000 km/60,000 mi
108 000 km/67,500 mi
120 000 km/75,000 mi
132 000 km/82,500 mi
144 000 km/90,000 mi
156 000 km/97,500 mi
168 000 km/105,000 mi
180 000 km/112,500 mi
192 000 km/120,000 mi
204 000 km/127,500 mi
216 000 km/135,000 mi
228 000 km/142,500 mi
240 000 km/150,000 mi
Rotate tires, if recommended for the vehicle, and
perform Required Services. (1) Check engine oil level
and oil life percentage. Change engine oil and filter,
if needed.
If equipped, check engine air filter life percentage
and status. Change engine air filter, if needed.
@ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @
Replace passenger compartment air filter. (2)@ @@@@@
If the vehicle is not equipped with the engine air
filter life system, replace engine air cleaner filter. (3)@ @@
Inspect evaporative control system. (4)@@@
Replace spark plugs. Inspect spark plug wires and/or
boots.@ @
Change automatic transmission fluid and filter.@@@
Change transfer case fluid, if equipped with
AWD. (5)@@@
Change rear axle fluid, if equipped with limited slip
differential. (5)@@@

Cadillac CT4 Owner Manual (GMNA-Localizing-U.S./Canada-14584335) -
2021 - CRC - 11/23/20
388 SERVICE AND MAINTENANCE
Footnotes—Maintenance Schedule
Additional Required Services -
Severe
(1) Vehicles with different size front
and rear tires do not have tire
rotation. See Tire Rotation0352.
(2) Or every two years, whichever
comes first. More frequent passenger
compartment air filter replacement
may be needed if driving in areas with
heavy traffic, poor air quality, high
dust levels, or environmental
allergens. Passenger compartment air
filter replacement may also be needed
if there is reduced airf low, window
fogging, or odors. Your GM dealer can
help determine when to replace the
filter.
(3) Or every four years, whichever
comes first. If driving in dusty
conditions, inspect the filter at each
oil change or more often as needed.
See Engine Air Cleaner/Filter 0316.
(4) Visually check all fuel and vapor
lines and hoses for proper attachment,
connection, routing, and condition. (5)
Do not directly power wash the
transfer case and/or front/rear axle
output seals. High pressure water can
overcome the seals and contaminate
the transfer case fluid. Contaminated
fluid will decrease the life of the
transfer case and/or axles and should
be replaced.
(6) Or every five years, whichever
comes first. See Cooling System0317.
(7) Or every 10 years, whichever
comes first. Inspect for fraying,
excessive cracking, or damage; replace,
if needed.
(8) Replace brake fluid every five
years. See Brake Fluid 0325.
(9) Or every 10 years, whichever
comes first. See Gas Strut(s)0328.
(10) Replace air conditioning
desiccant every seven years.Special Application
Services
.Severe Commercial Use Vehicles
Only: Lubricate chassis components
every oil change.
.Have underbody flushing service
performed. See "Underbody
Maintenance" in Exterior Care0370.
Additional Maintenance
and Care
Your vehicle is an important
investment and caring for it properly
may help to avoid future costly
repairs. To maintain vehicle
performance, additional maintenance
services may be required.
It is recommended that your dealer
perform these services —their trained
dealer technicians know your vehicle
best. Your dealer can also perform a
thorough assessment with a
multi-point inspection to recommend
when your vehicle may need
attention.

Cadillac CT4 Owner Manual (GMNA-Localizing-U.S./Canada-14584335) -
2021 - CRC - 11/23/20
SERVICE AND MAINTENANCE 389
The following list is intended to
explain the services and conditions to
look for that may indicate services are
required.
Battery
The 12-volt battery supplies power to
start the engine and operate any
additional electrical accessories.
.To avoid break-down or failure to
start the vehicle, maintain a battery
with full cranking power.
.Trained dealer technicians have the
diagnostic equipment to test the
battery and ensure that the
connections and cables are
corrosion-free.
Belts
.Belts may need replacing if they
squeak or show signs of cracking or
splitting.
.Trained dealer technicians have
access to tools and equipment to
inspect the belts and recommend
adjustment or replacement when
necessary. Brakes
Brakes stop the vehicle and are crucial
to safe driving.
.Signs of brake wear may include
chirping, grinding, or squealing
noises, or difficulty stopping.
.Trained dealer technicians have
access to tools and equipment to
inspect the brakes and recommend
quality parts engineered for the
vehicle.
Fluids
Proper fluid levels and approved fluids
protect the vehicle’s systems and
components. See Recommended Fluids
and Lubricants 0391 for GM approved
fluids.
.Engine oil and windshield washer
fluid levels should be checked at
every fuel fill.
.Instrument cluster lights may come
on to indicate that fluids may be
low and need to be filled. Hoses
Hoses transport fluids and should be
regularly inspected to ensure that
there are no cracks or leaks. With a
multi-point inspection, your dealer
can inspect the hoses and advise if
replacement is needed.
Lamps
Properly working headlamps,
taillamps, and brake lamps are
important to see and be seen on
the road.
.Signs that the headlamps need
attention include dimming, failure
to light, cracking, or damage. The
brake lamps need to be checked
periodically to ensure that they light
when braking.
.With a multi-point inspection, your
dealer can check the lamps and
note any concerns.

Cadillac CT4 Owner Manual (GMNA-Localizing-U.S./Canada-14584335) -
2021 - CRC - 11/23/20
TECHNICAL DATA 397
ApplicationCapacities
Metric English
Rear Axle
IOpen Differential - Small 0.75 L
0.79 qt
IOpen Differential - Large 1.0 L
1.0 qt
IMechanical Limited Slip 1.0 L
1.0 qt
Wheel Nut Torque (M12) 140Y 100 lb ft
All capacities are approximate. When adding, be sure to fill to the approximate level, as recommended in this manual.
Recheck fluid level after filling.
*Engine cooling system capacity values are based on the entire cooling system and its components.
Engine Specifications
Engine VIN CodeTransmission Spark Plug Gap
2.0L L4 Turbo Engine (LSY) KAutomatic0.65–0.75 mm (0.026–0.030 in)
2.7L L4 Turbo Engine (L3B) LAutomatic0.65–0.75 mm (0.026–0.030 in)
Spark plug gaps are preset by the manufacturer. Re-gapping the spark plug is not recommended and can damage the
spark plug.

Cadillac CT4 Owner Manual (GMNA-Localizing-U.S./Canada-14584335) -
2021 - CRC - 11/23/20
408 CUSTOMER INFORMATION
Managing the Vehicle Damage
Repair Process
In the event that the vehicle requires
damage repairs, GM recommends that
you take an active role in its repair.
If you have a pre-determined repair
facility of choice, take the vehicle
there, or have it towed there. Specify
to the facility that any required
replacement collision parts be original
equipment parts, either new Genuine
GM parts or recycled original GM
parts. Remember, recycled parts will
not be covered by the GM vehicle
warranty.
Insurance pays the bill for the repair,
but you must live with the repair.
Depending on your policy limits, your
insurance company may initially value
the repair using aftermarket parts.
Discuss this with the repair
professional, and insist on Genuine
GM parts. Remember, if the vehicle is
leased, you may be obligated to have
the vehicle repaired with Genuine GM
parts, even if your insurance coverage
does not pay the full cost.If another party's insurance company
is paying for the repairs, you are not
obligated to accept a repair valuation
based on that insurance company's
collision policy repair limits, as you
have no contractual limits with that
company. In such cases, you can have
control of the repair and parts choices
as long as the cost stays within
reasonable limits.
Publication Ordering
Information
Service Manuals
Service manuals have the diagnosis
and repair information on the engine,
transmission, axle, suspension, brakes,
electrical system, steering system,
body, etc.
Customer Literature
Owner’s manuals are written
specifically for owners and are
intended to provide basic operational
information about the vehicle. The
owner’s manual includes the
Maintenance Schedule for all models.Customer literature publications
available for purchase include owner’s
manuals, warranty manuals, and
portfolios. Portfolios include an
owner’s manual, warranty manual,
if applicable, and zip lock bag or
pouch.
Current and Past Models
Service manuals and customer
literature are available for many
current and past model year GM
vehicles.
To order, call 1-800-551-4123
Monday–Friday, 8:00 a.m.–6:00 p.m.
eastern time
For credit card orders only (VISA,
MasterCard, or Discover), see Helm,
Inc. at: www.helminc.com.
To order by mail, write to:
Helm, Incorporated
Attention: Customer Service
47911 Halyard Drive
Plymouth, MI 48170
Make checks payable in U.S. funds.

Cadillac CT4 Owner Manual (GMNA-Localizing-U.S./Canada-14584335) -
2021 - CRC - 11/23/20
414 ONSTAR
.Obtain and customize the Wi-Fi
hotspot name or SSID and
password, if equipped.
Press
Qto connect to an Advisor to:
.Verify account information or
update contact information.
.Get driving directions.
.Receive a Diagnostic check of the
vehicle's key operating systems.
.Receive Roadside Service.
.Manage Wi-Fi Settings, if equipped.
Press
>to get a priority connection
to an OnStar Advisor available 24/7 to:
.Get help for an emergency.
.Be a Good Samaritan or respond to
an AMBER Alert.
.Get assistance in severe weather or
other crisis situations and find
evacuation routes.
OnStar Services
Emergency
Emergency Services require an active
safety and security plan. With
Automatic Crash Response, built-in
sensors can automatically alert a specially trained OnStar Advisor who
is immediately connected in to the
vehicle to help.
Press
>for a priority connection to
an OnStar Advisor who can contact
emergency service providers, direct
them to your exact location, and relay
important information.
With OnStar Crisis Assist, specially
trained Advisors are available
24 hours a day, 7 days a week, to
provide a central point of contact,
assistance, and information during a
crisis.
With Roadside Service, Advisors can
locate a nearby service provider to
help with a flat tire, a battery jump,
or an empty gas tank.
Security
If equipped, OnStar provides these
services:
.With Stolen Vehicle Assistance,
OnStar Advisors can use GPS to
pinpoint the vehicle and help
authorities quickly recover it.
.With Remote Ignition Block,
if equipped, OnStar can block the
engine from being restarted.
.With Stolen Vehicle Slowdown,
if equipped, OnStar can work with
law enforcement to gradually slow
the vehicle down.
Theft Alarm Notification
If equipped, if the doors are locked
and the vehicle alarm sounds, a
notification by text, e-mail, or phone
call will be sent. If the vehicle is
stolen, an OnStar Advisor can work
with authorities to recover the vehicle.
OnStar Additional
Information
In-Vehicle Audio Messages
Audio messages may play important
information at the following times:
.Prior to vehicle purchase. PressQ
to set up an account.
.After change in ownership and at
90 days.

Cadillac CT4 Owner Manual (GMNA-Localizing-U.S./Canada-14584335) -
2021 - CRC - 11/23/20
INDEX 421
IndexA
Accessories and Modifications . . . . . 306
Accessory Power . . . . . . . . . . . . . . . . . . . . 223
Adaptive Cruise Control . . . . . . . . . . . . 251
Add-On Electrical Equipment . . . . . . 303
Additional InformationOnStar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 414
Additional Maintenance and Care . . . . . . . . . . . . . . . . . . . . . . . . . . . 388
Adjustments
Lumbar, Front Seats . . . . . . . . . . . . . . . 32
Thigh Support . . . . . . . . . . . . . . . . . . . . . 33
Agreements Trademarks and License . . . . . . . . . 187
Air Cleaner/Filter, Engine . . . . . . . . . . 316
Air Conditioning . . . . . . . . . . . . . . . . . . . . 196
Air Filter Life System . . . . . . . . . . . . . . . . . . . . . . . . 315
Air Filter, Passenger
Compartment . . . . . . . . . . . . . . . . . . . . . 201
Air Vents . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200
Airbag System Check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
How Does an Airbag Restrain? . . . . 52
Passenger Sensing System . . . . . . . . 53
What Makes an AirbagInflate? . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 Airbag System (cont'd)
What Will You See after an
Airbag Inflates? . . . . . . . . . . . . . . . . . . 52
When Should an Airbag Inflate? . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
Where Are the Airbags? . . . . . . . . . . . 49
Airbags
Adding Equipment to theVehicle . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Passenger Status Indicator . . . . . . . . 96
Readiness Light . . . . . . . . . . . . . . . . . . . . 96
Servicing Airbag-Equipped Vehicles . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
System Check . . . . . . . . . . . . . . . . . . . . . . 48
Alarm Vehicle Security . . . . . . . . . . . . . . . . . . . . 20
Alert Lane Change . . . . . . . . . . . . . . . . . . . . . . 289
Rear Pedestrian . . . . . . . . . . . . . . . . . . . 282
Side Blind Zone (SBZA) . . . . . . . . . . 289
All-Season Tires . . . . . . . . . . . . . . . . . . . . . 339
All-Wheel Drive . . . . . . . . . . . . . . . .236, 327
AM-FM Radio . . . . . . . . . . . . . . . . . . . . . . . 141
Antenna
Multi-band . . . . . . . . . . . . . . . . . . . . . . . . 145
Antilock Brake System (ABS) . . . . . . 236
Warning Light . . . . . . . . . . . . . . . . . . . . 100

Cadillac CT4 Owner Manual (GMNA-Localizing-U.S./Canada-14584335) -
2021 - CRC - 11/23/20
INDEX 423
Chains, Tire . . . . . . . . . . . . . . . . . . . . . . . . . 358
ChargingWireless . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
Charging System Light . . . . . . . . . . . . . . 97
Check Engine Light (MalfunctionIndicator) . . . . . . . . . . . . . . . . . . . . . . . . . 97
Child Restraints Infants and Young Children . . . . . . . 60
Lower Anchors and Tethersfor Children . . . . . . . . . . . . . . . . . . . . . . . 65
Older Children . . . . . . . . . . . . . . . . . . . . . 59
Securing . . . . . . . . . . . . . . . . . . . . . . . . 72, 74
Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
Circuit Breakers . . . . . . . . . . . . . . . . . . . . . 331
Cleaning Exterior Care . . . . . . . . . . . . . . . . . . . . . . 370
Interior Care . . . . . . . . . . . . . . . . . . . . . . 375
Climate Control Systems Dual Automatic . . . . . . . . . . . . . . . . . . . 196
Clock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
Cluster, Instrument . . . . . . . . . . . . . . 88, 90
Collision Damage Repair . . . . . . . . . . . 406
Compartments Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
Compass . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
Competitive Driving Mode . . . . . . . . . 246
Composite Materials . . . . . . . . . . . . . . . . 218 Compressor Kit, Tire Sealant . . . . . . . 360
Connected Services
Connections . . . . . . . . . . . . . . . . . . . . . . . 419
Diagnostics . . . . . . . . . . . . . . . . . . . . . . . . 420
Navigation . . . . . . . . . . . . . . . . . . . . . . . . . 418
Connections Connected Services . . . . . . . . . . . . . . . 419
Control Traction and ElectronicStability . . . . . . . . . . . . . . . . . . . . . . . . . . 239
Control of a Vehicle . . . . . . . . . . . . . . . . 204
Controls
Steering Wheel . . . . . . . . . . . . . . . . . . . . 137
Convex Mirrors . . . . . . . . . . . . . . . . . . . . . . 23
Coolant Engine Temperature Gauge . . . 94, 95
Engine Temperature Warning
Light . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
Cooling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 196
Cooling System . . . . . . . . . . . . . . . . . . . . . 317
Cornering Lamps . . . . . . . . . . . . . . . . . . . 130
Courtesy Lamps . . . . . . . . . . . . . . . . . . . . . 130
Courtesy Transportation Program . . . . . . . . . . . . . . . . . . . . . . . . . . . . 405
Coverage Explanations . . . . . . . . . . . . . 163
Cruise Control . . . . . . . . . . . . . . . . . . . . . . . 248
Light . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
Cruise Control, Adaptive . . . . . . . . . . . 251 Cruise Control, Super . . . . . . . . . . . . . . . 260
Cupholders . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
Customer Assistance . . . . . . . . . . . . . . . 402
Offices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 401
Text Telephone (TTY) Users . . . . . 402
Customer Information Publications Ordering
Information . . . . . . . . . . . . . . . . . . . . . . 408
Customer Satisfaction Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . 399
Cybersecurity . . . . . . . . . . . . . . . . . . . . . . . . 410
D
Damage Repair, Collision . . . . . . . . . . . 406
Danger, Warning, and Caution . . . . . . . . 2
Data Collection Infotainment System . . . . . . . . . . . . . 412
OnStar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 412
Data Recorders, Event . . . . . . . . . . . . . . 411
Database Coverage Explanations . . . . . . . . . . . . . . . . . . . . . . 163
Daytime Running Lamps (DRL) . . . 128
Defensive Driving . . . . . . . . . . . . . . . . . . . 204
Delayed Locking . . . . . . . . . . . . . . . . . . . . . 17
Destination . . . . . . . . . . . . . . . . . . . . . . . . . . 155
Diagnostics Connected Services . . . . . . . . . . . . . . . 420
Differential, Limited-Slip . . . . . . . . . . . 248