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Braking effect after a collisionIn certain types of collisions, the vehicle's brakes are applied to help prevent or mitigate a secon-dary collision.
Maintaining control of the vehicle after a collision may be difficult. To help avoid or mitigate theeffect of a secondary collision, the brakes areapplied automatically to help bring the vehicle toa stop. The brake lights and hazard warning flashers will be activated and the flashers will remain on afterthe vehicle has come to a standstill. The parkingbrake will then be applied automatically. In a situation where stopping the vehicle may not be desirable, the driver can override this systemby pressing the accelerator pedal. This feature can only function if the brake system is intact after the collision.
Related information
• Brake functions (p. 348)
• Airbag system (p. 89)
• Rear Collision Warning (RCW) (p. 292)
Emergency brake lights
The emergency brake lights activate in the event of hard braking/rapid deceleration at most nor-mal driving speeds or if the ABS system is acti-vated. This function causes an additional taillighton each side of the vehicle to illuminate to helpalert vehicles traveling behind.
Once the emergency brake lights have been acti- vated, if the driver releases the brake pedal, thebrake lights will return to their normal function.
Related information
• Brakes (p. 346)
• Hazard warning flashers (p. 147)
• Brake lights (p. 146)
Hill Descent Control (HDC) HDC is a type of low-speed automatic engine brake and makes it possible to increase ordecrease the vehicle's speed on steep downhillgradients using only the accelerator pedal, with-out applying the brakes. HDC is integrated into the
Off Road drive
mode.
HDC is particularly useful when driving down steep hills with rough surfaces, and where theroad may have slippery patches.
WARNING
HDC does not function in all situations, and is a supplementary braking aid. The driver hasfull responsibility for driving in a safe manner.
FunctionHDC allows the vehicle to roll forward or in reverse at very low speed with enhanced enginebraking. However, speed can be adjusted withthe accelerator pedal. When the acceleratorpedal is released, the vehicle will return to verylow speed. The driver can use the brakes to slow or stop the vehicle at any time. HDC is activated along with Low Speed Control (LSC), which together make driving on slipperysurfaces at low speeds easier.

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Parking brake The electric parking brake helps to keep the vehicle stationary when it is parked.
Parking brake control in the tunnel console between the front seats
NOTE
•A faint sound from the parking brake's electric motor can be heard when theparking brake is being applied. Thissound can also be heard during the auto-matic function check of the parkingbrake.
• The brake pedal will move slightly whenthe electric parking brake is applied orreleased.
If the vehicle is not moving when the parking brake is applied, only the rear wheels are affec- ted. If it is applied while the vehicle is moving, thenormal brakes are used on all four wheels. Thebrakes will only be applied on the rear wheelsonce the vehicle has stopped.
Related information
•
Brake functions (p. 348)
• Using the parking brake (p. 352)
• Parking brake malfunctions (p. 354)
Using the parking brake
The electric parking brake helps to keep the vehicle stationary when it is parked.
Applying the parking brake
1. Put the gear selector in P.
2. Press firmly on the brake pedal.
3. Pull up the control. > The symbol in the instrument panelflashes while the parking brake is being applied and glows steadily when the park-ing brake has been fully applied.
4. Release the brake pedal and ensure that the vehicle is stationary.

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Before a long distance trip
It is always worthwhile to have your vehicle checked by a trained and qualified Volvo servicetechnician before driving long distances. Yourretailer will also be able to supply you with bulbs,fuses, spark plugs and wiper blades for your usein the event that problems occur.
As a minimum, the following items should be checked before any long trip:
• Check that engine runs smoothly and that fuel consumption and the oil level are normal.
• Before leaving on a trip, fill the fuel tank andmake sure the hybrid battery is fully charged.During the trip, make a habit of refueling reg-ularly.
• Check for fuel, oil, and fluid leakage.
• Check condition of drive belts.
• Check state of the battery's charge.
• Examine tires carefully and replace thosethat are worn. Also, check tire inflation pres-sure.
• The brakes, front wheel alignment, and steer-ing gear should be checked by a trained andqualified Volvo service technician only.
• Check all lights, including high beams.
• Reflective warning triangles are legallyrequired in some states/provinces.
• Have a word with a trained and qualifiedVolvo service technician if you intend to drive in countries where it may be difficult toobtain the correct fuel.
• Consider your destination. If you will be driv-ing through an area where snow or ice arelikely to occur, consider using snow tires.
Driving economically
Better driving economy can be obtained by thinking ahead, avoiding rapid starts and stopsand adjusting the speed of your vehicle to imme-diate traffic conditions.
Driving economically with the XC90 T8Twin Engine Plug-in Hybrid
Plan your driving in order to utilize the electric motor as much as possible. An energy-conserving driving style lowers current consumption from the hybrid battery and helpsincrease electric driving range.
Charging
• Charge the hybrid battery regularly using the charging cable. Whenever possible, begin adrive with a fully charged battery.
• Check the location of charging points.
• Where possible, choose parking spaces withcharging points.

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Driving through standing water
The vehicle should be driven with extreme cau- tion if it is necessary to drive through standingwater.
The vehicle can be driven through water up to a depth approximately level with the floor at walk-ing speed to help prevent water from enteringthe differential and/or the transmission or dam-aging electrical components. • If possible, check the depth of the water before driving through it. Take particular carewhen driving through flowing water.
• Before driving through water, always select the
Off Road drive mode to ensure that the
gasoline engine is running and to maximize ground clearance.
• After driving through water, apply the brakesand check that they are functioning correctly.
• Clean the electrical connections for trailerwiring after driving in mud or water.
• When driving through water, maintain lowspeed and do not stop in the water.
CAUTION
• Damage may occur to the engine, trans- mission, electrical components, etc. if thevehicle is driven through water higherthan its floor level. Be aware that wavescreated by other vehicles could cause thelevel to temporarily be above the vehicle'sfloor level.
• Damage to any components due to waterabove the floor level, vapor lock or insuffi-cient oil is not covered under warranty.
• If the engine has been stopped while thevehicle is in water, do not attempt torestart it. Have the vehicle towed out ofthe water and inspected by a trained andqualified Volvo service technician.
WARNING
• Avoid driving through standing or rushing water. Doing so can be dangerous and itmay also be difficult to determine theactual depth of the water.
• If water cannot be avoided, after drivingthrough the water, press lightly on thebrake pedal to ensure that the brakes arefunctioning normally. Water or mud canmake the brake linings slippery, resultingin delayed braking effect.
Related information
•
Towing recommendations (p. 360)
Overheating the engine and transmission
In demanding driving conditions, such as when transporting heavy loads, driving in mountainousareas or in very hot weather there is a risk ofoverheating the engine or transmission.
• The engine's output may be slightly limited if there is a risk of overheating.
• Remove e.g., auxiliary lights mounted in frontof the grille in hot weather.
• If the temperature of the engine coolantbecomes too high, the warning symbol will illuminate and the message
Engine
temperature/Stop safely will be displayed.
Stop the vehicle as soon as possible in a safe place and let the engine idle for severalminutes.
• If the message
Engine temperature/High
temperature Turn off engine or Engine
coolant/Stop safely is displayed, stop
safely and turn off the engine.
• If the transmission begins to overheat, an alternative gear shifting program will beselected. An integrated protective functionwill also by activated, the warning symbol will illuminate and the message
Transmission
warmHigh temperature Reduce speed
or Transmission warmStop safely, wait
for cooling will be displayed in the instru-
ment panel.

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The air conditioning may be switched off temporarily.
• After a prolonged period of driving, do notturn off the engine immediately after stop-ping.
• The engine cooling fan commonly continuesto run for several minutes after the enginehas been turned off.
WARNING
The cooling fan (located at the front of the engine compartment, behind the radiator) maystart or continue to operate (for up to6 minutes) after the engine has beenswitched off.
Related information
•
Driving with a trailer (p. 367)
• Before a long distance trip (p. 355)
Winter driving
Check your vehicle before the approach of cold weather.
The following advice is worth noting:
• Make sure that the engine coolant contains 50 percent antifreeze. Any other mixture willreduce freeze protection. This gives protec-tion against freezing down to –31 °F(–35 °C). The use of "recycled" antifreeze isnot approved by Volvo. Different types ofantifreeze must not be mixed.
• Volvo recommends using only genuine Volvoantifreeze in your vehicle's radiator.
• Try to keep the fuel tank well filled – thishelps prevent the formation of condensationin the tank. In addition, in extremely coldweather conditions it is worthwhile to addfuel line de-icer before refueling.
• The viscosity of the engine oil is important.Oil with low viscosity (thinner oil) improvescold-weather starting as well as decreasingfuel consumption while the engine is warm-ing up. Full synthetic 0W-30 oil is recom-mended for driving in areas with sustainedlow temperatures.
• The load placed on the battery is greater dur-ing the winter since the windshield wipers,lighting, etc., are used more often. Moreover,the capacity of the battery decreases as thetemperature drops. In very cold weather, apoorly charged battery can freeze and bedamaged. It is therefore advisable to check the state of charge more frequently andspray an anti-rust oil on the battery posts.
• Volvo recommends the use of snow tires onall four wheels for winter driving.
• To prevent the washer fluid reservoir fromfreezing, add washer solvents containingantifreeze. This is important since dirt is oftensplashed on the windshield during winterdriving, requiring the frequent use of thewashers and wipers. Volvo Washer Solventshould be diluted as follows: Down to 14 °F(–10 °C): 1 part washer solvent and 4 partswater Down to 5 °F (–15 °C): 1 part washersolvent and 3 parts water Down to 0 °F(–18 °C): 1 part washer solvent and 2 partswater Down to –18 °F (–28 °C): 1 partwasher solvent and 1 part water.
• Use Volvo Teflon Lock Spray in the locks.
• Avoid using de-icing sprays as they cancause damage to the locks.
Related information
• Snow tires and chains (p. 451)

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* Option/accessory, for more information, see Introduction.
360
Towing recommendations
Always check with state and local authorities before attempting to tow another vehiclebecause this type of towing is subject to regula-tions regarding maximum towing speed, lengthand type of towing device, lighting, etc.
Towing your vehicle behind another vehicle
The XC90 T8 Twin Engine Plug-in Hybrid may not be towed behind another vehicle. Doing sowould damage the electric motor and the three-way catalytic converter. If the vehicle cannot bedriven and must be moved, it must be lifted ontoa flat-bed tow truck. If the XC90 T8 Twin Engine Plug-in Hybrid is to tow (pull) another vehicle, select the
AWD drive
mode. This helps charge the hybrid battery and improves the vehicle's road holding characteris-tics.
Tow trucks
CAUTION
In certain conditions, the towing eyelet may be used to pull the vehicle onto aflatbed tow truck.
• The vehicle's position and ground clear- ance determine if it can be pulled up ontoa flatbed tow truck using the towing eye-let.
• If the angle of the tow truck

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WARNING
•Do not connect the jumper cable to any part of the fuel system or to any movingparts. Avoid touching hot manifolds.
• Batteries generate hydrogen gas, whichis flammable and explosive.
• Battery fluid contains sulfuric acid. Do notallow battery fluid to contact eyes, skin,fabrics or painted surfaces. If contactoccurs, flush the affected area immedi-ately with water. Obtain medical helpimmediately if eyes are affected.
• Never expose the battery to open flameor electric spark.
• Do not smoke near the battery.
• Failure to follow the instructions for jumpstarting can lead to injury.
Related information
• Towing eyelet (p. 359)
• Jump starting (p. 365)
• Parking brake (p. 352)
• Ignition modes (p. 370)
Fuel Volvo recommends the use of detergent gaso- line to control engine deposits.
Deposit control gasoline (detergent
additives)
Detergent gasoline is effective in keeping injec- tors and intake valves clean. Consistent use ofdeposit control gasolines will help ensure gooddrivability and fuel economy. If you are not surewhether the gasoline contains deposit controladditives, check with the service station operator.
NOTE
Volvo does not recommend the use of exter- nal fuel injector cleaning systems.
Unleaded fuelEach Volvo has a three-way catalytic converter and must use only unleaded gasoline. U.S. andCanadian regulations require that pumps deliver-ing unleaded gasoline be labeled "UNLEADED".Only these pumps have nozzles which fit yourvehicle's filler inlet. It is unlawful to dispense lea-ded fuel into a vehicle labeled "unleaded gaso-line only". Leaded gasoline damages the three-way catalytic converter and the heated oxygensensor system. Repeated use of leaded gasolinewill lessen the effectiveness of the emission con-trol system and could result in loss of emissionwarranty coverage. State and local vehicle inspection programs will make detection of mis-fueling easier, possibly resulting in emission testfailure for misfueled vehicles.
NOTE
Some U.S. and Canadian gasolines contain an octane enhancing additive called methyl-cyclopentadienyl manganese tricarbonyl(MMT). If such fuels are used, your EmissionControl System performance may be affected,and the Check Engine Light (malfunctionindicator light) located on your instrumentpanel may light. If this occurs, please returnyour vehicle to a trained and qualified Volvoservice technician for service.
Gasoline containing alcohol and ethers, "Oxygenated fuels"
Some fuel suppliers sell gasoline containing "oxygenates" which are usually alcohols orethers. In some areas, state or local laws requirethat the service pump be marked indicating useof alcohols or ethers. However, there are areas inwhich the pumps are unmarked. If you are notsure whether there is alcohol or ethers in thegasoline you buy, check with the service stationoperator. To meet seasonal air quality standards,some areas require the use of "oxygenated" fuel. Volvo allows the use of the following "oxygen- ated" fuels; however, the octane ratings listedmust still be met.

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Use of AdditivesWith the exception of gas line antifreeze during winter months, do not add solvents, thickeners, orother store-bought additives to your vehicle'sfuel, cooling, or lubricating systems. Overuse maydamage your engine, and some of these additivescontain organically volatile chemicals. Do notneedlessly expose yourself to these chemicals.
WARNING
Never carry a cell phone that is switched on
while refueling your vehicle. If the phone rings, this may cause a spark that could ignite gaso-line fumes, resulting in fire and injury.
WARNING
Carbon monoxide is a poisonous, colorless, and odorless gas. It is present in all exhaustgases. If you ever smell exhaust fumes insidethe vehicle, make sure the passenger com-partment is ventilated, and immediately returnthe vehicle to a trained and qualified Volvoservice technician for correction.
Related information
• Fuel (p. 361)
Opening/closing the fuel filler door The fuel tank has a filling system that does not have a cover.
Opening/closing the fuel filler doorAn arrow next to the fuel pump symbol in the instrument panelindicates the side of the vehiclewhere the fuel filler door islocated.
1. Press the button on the lighting panel.
> Pressure equalization in the fuel tank cau-ses a slight delay before the fuel filler door opens.
Fuel tank Fuel lid is
opening will be displayed in the instru-
ment panel, followed by Fuel tank Ready
for refueling.
2. After refueling, close the fuel filler door by pressing lightly.