ECU MERCEDES-BENZ GLA 2019 Repair Manual

Example: engine oil cap
XTurn capCcounter-clockwise and removeit.
XAdd engine oil.If the oil level is at or below the MIN markon the oil dipstick, add 1.1 US qt (1.0 liter)of engine oil.
XReplace capCon the filler neck and turnclockwise.Ensure that the cap locks into placesecurely.
XCheck the oil level again with the oil dipstick(Ypage 274).
Further information on engine oil(Ypage 336).
Checking and adding other service
products
Checking coolant level
GWARNING
The cooling system is pressurized, particu-
larly when the motor is warm. If you open
the cap, you could be scalded if hot coolant
sprays out. There is a risk of injury.
Let the engine cool down before you open
the cap. Wear protective gloves and protec-
tive eyewear when opening. Open the cap
slowly to release pressure.
!The coolant level must only be checkedand corrected when the engine has cooleddown (coolant temperature under 104 ‡(40 †). Checking the coolant level when thecoolant temperature is over 104 ‡ (40 †)can lead to damage to the engine or theengine cooling system.
XPark the vehicle on a level surface.
Only check the coolant level when the vehi-cle is on a level surface and the engine hascooled down.
XTurn the SmartKey to positionHin the igni-tion lock (Ypage 125).
XCheck the coolant temperature display inthe instrument cluster.The coolant temperature must be below104 ‡ (40 †).
XTurn the SmartKey to positionZ(Ypage 125) in the ignition lock .
XSlowly turn capCcounter-clockwise and torelieve excess pressure.
XTurn capCfurther counter-clockwise andremove it.If the coolant is at the level of marker bar

Always switch off the windshield wipers and
the ignition before cleaning the windshield
or wiper blades.
!Only fold the windshield wipers away fromthe windshield when vertical. Otherwise, youwill damage the hood.
!Do not use dry cloths, abrasive products,solvents or cleaning agents containing sol-vents to clean the inside of the windows. Donot touch the insides of the windows withhard objects, e.g. an ice scraper or ring.There is otherwise a risk of damaging thewindows.
!Clean the water drainage channels of thewindshield and the rear window at regularintervals. Deposits such as leaves, petalsand pollen may under certain circumstancesprevent water from draining away. This canlead to corrosion damage and damage toelectronic components.
XClean the inside and outside of the windowswith a damp cloth and a cleaning productthat is recommended and approved byMercedes-Benz.
Cleaning wiper blades
GWARNING
You could become trapped by the wind-
shield wipers if they start moving while
cleaning the windshield or wiper blades.
There is a risk of injury.
Always switch off the windshield wipers and
the ignition before cleaning the windshield
or wiper blades.
!Only fold the windshield wipers away fromthe windshield when vertical. Otherwise, youwill damage the hood.
!Do not pull the wiper blade. Otherwise, thewiper blade could be damaged.
!Do not clean wiper blades too often anddo not rub them too hard. Otherwise, thegraphite coating could be damaged. Thiscould cause wiper noise.
!Hold the wiper arm securely when foldingback. The windshield could be damaged ifthe wiper arm smacks against it suddenly.
XFold the windshield wiper arms away fromthe windshield.
XCarefully clean the wiper blades with adamp cloth.
XFold the windshield wiper arms back againbefore switching on the ignition.
Cleaning the exterior lighting
!Only use cleaning agents or cleaningcloths that are suitable for plastic lenses.Caustic, irritant or otherwise unsuitablecleaning agents or cleaning cloths couldscratch or damage the exterior lighting plas-tic lenses.
XClean the plastic lenses of the exterior lightswith a wet sponge and a mild cleaningagent, e.g. Mercedes-Benz car shampoo orcleaning cloths.
Cleaning the mirror turn signals
!Only use cleaning agents or cleaningcloths that are suitable for plastic lenses.Unsuitable cleaning agents or cleaningcloths could scratch or damage the plasticlenses of the mirror turn signals.
XClean the plastic lenses of the mirror turnsignals in the exterior mirror housing using awet sponge and mild cleaning agent, e.g.Mercedes-Benz car shampoo or cleaningcloths.
Cleaning the sensors
!If you clean the sensors with a powerwasher, make sure that you keep a distanceof at least 11.8 in (30 cm) between the vehi-cle and the power washer nozzle. Informa-tion about the correct distance is availablefrom the equipment manufacturer.
282Care
Maintenance and care

or sparks are created, the hydrogen gas can
ignite. There is a risk of an explosion.
RMake sure that the positive terminal of a
connected battery does not come into
contact with vehicle parts.
RNever place metal objects or tools on a
battery.
RIt is important that you observe the
described order of the battery terminals
when connecting and disconnecting a bat-
tery.
RWhen jump-starting, make sure that the
battery poles with identical polarity are
connected.
RIt is particularly important to observe the
described order when connecting and dis-
connecting the jumper cables.
RNever connect or disconnect the battery
terminals while the engine is running.
GWARNING
Battery acid is caustic. There is a risk of
injury.
Avoid contact with skin, eyes or clothing. Do
not inhale any battery gases. Do not lean
over the battery. Keep children away from
batteries. Wash away battery acid immedi-
ately with plenty of clean water and seek
medical attention.
HEnvironmental note
Batteries contain pollutants.
It is illegal to dispose of
them with the household
rubbish. They must be col-
lected separately and dis-
posed of in an environmen-
tally responsible recycling
system.
Dispose of batteries in an
environmentally responsible
manner. Take discharged
batteries to a qualified spe-
cialist workshop or to a col-
lection point for used bat-
teries.
!Have the battery regularly checked at aqualified specialist workshop.
Comply with the service intervals in theMaintenance Booklet, or contact a qualifiedspecialist workshop for more information.
!You should have all work involving the bat-tery carried out at a qualified specialistworkshop. In the exceptional case that it isnecessary for you to disconnect the batteryyourself, make sure that:
Rswitch off the engine and remove theSmartKey. On vehicles with KEYLESS-GO,make sure that the ignition is switchedoff. Check that all the indicator lamps inthe instrument cluster are off. Otherwise,electronic components, such as the alter-nator, may be damaged.
Ryou first remove the negative terminalclamp and then the positive terminalclamp. Never swap the terminal clamps.Otherwise, the vehicle's electronic systemmay be damaged.
Rin vehicles with automatic transmission,the transmission is locked in position]after the battery is disconnected. Thevehicle is secured against rolling away.You can then no longer move the vehicle.
The battery and the cover of the positive ter-minal clamp must be installed securely dur-ing operation.
Comply with safety precautions and take pro-tective measures when handling batteries.
Risk of explosion.
Fire, open flames and smoking areprohibited when handling the bat-tery. Avoid creating sparks.
Battery acid is caustic. Avoid con-tact with skin, eyes or clothing.
Wear suitable protective clothing,especially gloves, apron and face-guard.
Rinse any acid spills immediatelywith clear water. Contact a physi-cian if necessary.
Battery (vehicle)293
Roadside Assistance
Z

GWARNING
During the charging process, a battery produces hydrogen gas. If a short circuit occurs or
sparks are created, the hydrogen gas can ignite. There is a risk of an explosion.
RMake sure that the positive terminal of a connected battery does not come into contact with
vehicle parts.
RNever place metal objects or tools on a battery.
RIt is important that you observe the described order of the battery terminals when connect-
ing and disconnecting a battery.
RWhen jump-starting, make sure that the battery poles with identical polarity are connected.
RIt is particularly important to observe the described order when connecting and disconnect-
ing the jumper cables.
RNever connect or disconnect the battery terminals while the engine is running.
GWARNING
A discharged battery can freeze at temperatures below freezing point. When jump-starting the
vehicle or charging the battery, gases can escape from the battery. There is a risk of an explo-
sion.
Allow the frozen battery to thaw out before charging it or jump-starting.
!Avoid repeated and lengthy starting attempts. Otherwise, the catalytic converter could bedamaged by the non-combusted fuel.
If the indicator/warning lamps do not light up in the instrument cluster at low temperatures, it isvery likely that the discharged battery has frozen. In this case you may neither jump-start thevehicle nor charge the battery. Let the battery thaw first. The service life of a thawed-out batterymay be shorter. The starting characteristics can be impaired, particularly at low temperatures.Have the thawed-out battery checked at a qualified specialist workshop.
Do not start the vehicle using a rapid charging device. If your vehicle's battery is discharged, theengine can be jump-started from another vehicle or from a second battery using jumper cables.Observe the following points:
RThe battery is not accessible in all vehicles. If the other vehicle's battery is not accessible,jump-start the vehicle using a second battery or a jump-starting device.
RYou may only jump-start the vehicle when the engine and exhaust system are cold.
RDo not start the engine if the battery is frozen. Let the battery thaw first.
ROnly jump-start from batteries with a 12 V voltage rating.
ROnly use jumper cables that are not damaged and have a sufficient cross-section and insula-ted terminal clamps.
RMake sure that the two vehicles do not touch.
Make sure that:
RThe jumper cables are not damaged.
RNon-insulated parts of the terminal clamps do not come into contact with other metal partswhile the jumper cables are connected to the battery.
RThe jumper cables cannot come into contact with parts that can move when the engine is run-ning, such as the V-belt pulley or the fan.
XSecure the vehicle by applying the electric parking brake.
XShift the transmission to position].
XTurn the SmartKey to positionZin the ignition lock and remove it.
296Jump-starting
Roadside Assistance

Towing and tow-starting
Important safety notes
GWARNING
Functions relevant to safety are restricted or
no longer available if:
Rthe engine is not running
Rthe brake system or the power steering is
malfunctioning
Rthere is a malfunction in the power supply
or the vehicle's electrical system
When your vehicle is towed away or towed
started, you may require considerably more
effort to steer and brake. There is a risk of
an accident.
In such cases, use a tow bar. Before being
towed away or tow started, make sure the
steering moves freely.
GWARNING
You can no longer steer the vehicle if the
steering wheel lock has been engaged.
There is a risk of an accident.
Always switch off the ignition when towing
the vehicle with a tow cable or a tow bar.
GWARNING
When towing or tow-starting another vehicle
and its weight is greater than the permissi-
ble gross weight of your vehicle, the:
Rthe towing eye could detach itself
Rthe vehicle/trailer combination could roll-
over.
There is a risk of an accident.
When towing or tow-starting another vehi-
cle, its weight should not be greater than
the permissible gross weight of your vehicle.
Details on the permissible gross vehicle weightof your vehicle can be found on the vehicleidentification plate (Ypage 333).
!When Active Brake Assist, Active DistanceAssist DISTRONIC or the HOLD function isactivated, the vehicle brakes automaticallyin certain situations.
To avoid damage to the vehicle, deactivatethese systems in the following or similar sit-uations:
Rwhen towing the vehicle
Rin the car wash
!Make sure that the electric parking brakeis released. If the electric parking brake isfaulty, visit a qualified specialist workshop.
!Only secure the tow rope or tow bar at thetowing eyes. Otherwise, the vehicle could bedamaged.
!Do not use the towing eyes for recoverypurposes as this could damage the vehicle.If in doubt, recover the vehicle with a crane.
!When towing, pull away slowly andsmoothly. If the tractive power is too high,the vehicles could be damaged.
!The vehicle can be towed a maximum of30 miles (50km). The towing speed of30 mph (50km/h) must not be exceeded.
If the vehicle has to be towed more than30 miles (50km), the front axle must beraised or the entire vehicle raised and trans-ported.
!Do not tow with sling-type equipment. Thiscould damage the vehicle.
!When towing away vehicles with KEYLESS-GO, use the key instead of the Start/Stopbutton. The automatic transmission mayotherwise shift to position]when youopen the driver's or front-passenger door,which could damage the transmission.
!Vehicles with automatic transmission mustnot be started by tow-starting. This couldotherwise damage the transmission.
It is better to have the vehicle transportedthan to have it towed away.
If the vehicle can no longer be driven becauseof an accident or breakdown, you have the fol-lowing options:
RTransporting the vehicle.
As a rule, you should have the vehicle trans-ported.
RTowing the vehicle with a tow rope or towbar.
Only tow the vehicle in exceptional cases.
298Towing and tow-starting
Roadside Assistance

XWhen the vehicle is stationary, depress thebrake pedal and keep it depressed.
XShift the automatic transmission to position].
XRelease the brake pedal.
XRelease the electric parking brake.
XSwitch off the automatic locking(Ypage 199).
XSwitch on the hazard warning lamps(Ypage 104).
XTurn the SmartKey in the ignition lock topositionZand leave the SmartKey in theignition lock.
Towing a vehicle with both axles on
the ground
It is important that you observe the safetyinstructions when towing away your vehicle(Ypage 298).
XOn vehicles with KEYLESS-GO or theKEYLESS-GO start function:you must usethe SmartKey instead of the Start/Stop but-ton (Ypage 126).
The automatic transmission automaticallyshifts to position]when you open the driv-er's or front-passenger door or when youremove the SmartKey from the ignition lock. Inorder to ensure that the automatic transmis-sion stays in position\\when towing awaythe vehicle, you must observe the followingpoints:
XMake sure that the vehicle is stationary.
XTurn the SmartKey to positionHin the igni-tion lock.
XDepress and hold the brake pedal.
XShift the automatic transmission to position\\.
XLeave the SmartKey in positionHin theignition lock.
XRelease the brake pedal.
XRelease the electric parking brake.
XSwitch on the hazard warning lamps(Ypage 104).
iIn order to signal a change of directionwhen towing the vehicle with the hazardwarning lamps switched on, use the combi-nation switch as usual. In this case, only theindicator lamps for the direction of travel
flash. After resetting the combinationswitch, the hazard warning lamp startsflashing again.
Permitted towing methods
Mercedes-Benz recommends transporting yourvehicle in the case of a breakdown, rather thantowing it away.
When towing away, use a towing rope or atowing bar with both axles on the ground. Donot use any tow bar systems.
Transporting the vehicle
Vehicles with automatic transmission
!When the vehicle is loaded for transport,the front and rear axles must be stationaryand on the same transportation vehicle.Positioning over the connection point of thetransport vehicle is not permitted. The drivetrain may otherwise be damaged.
All vehicles
!You may only secure the vehicle by thewheels, not by parts of the vehicle such asaxle or steering components. Otherwise, thevehicle could be damaged.
XTurn the SmartKey to positionHin the igni-tion lock (Ypage 125).
XShift the transmission to position\\.
As soon as the vehicle has been loaded:
XPrevent the vehicle from rolling away byapplying the electric parking brake.
XShift the transmission to position].
300Towing and tow-starting
Roadside Assistance

XTurn the SmartKey to positionZin the igni-tion lock and remove it.
XSecure the vehicle.
The towing eye can be used to pull the vehicleonto a trailer or transporter for transportingpurposes.
Notes on 4MATIC vehicles
!Vehicles with 4MATIC must not be towedwith either the front or the rear axle raised,as doing so will damage the transmission.
Vehicles with 4MATIC may only either betowed away with both axles on the ground orbe loaded up and transported.
If the vehicle's transmission, front, or rear axleis damaged, have the vehicle transported on atruck or trailer.
In the event of damage to the electricalsystem:
If the battery is defective, the automatic trans-mission will be locked in position]. To shiftthe automatic transmission to position\\, youmust provide power to the vehicle's on-boardelectrical system in the same way as whenjump-starting (Ypage 295).
Have the vehicle transported on a transporteror trailer.
Tow-starting (emergency engine
starting)
!Vehicles with automatic transmission mustnot be tow-started. You could otherwisedamage the automatic transmission.
iYou can find information on "Jump-start-ing" under (Ypage 295).
Fuses
Important safety notes
GWARNING
If you manipulate or bridge a faulty fuse or if
you replace it with a fuse with a higher
amperage, the electric cables could be over-
loaded. This could result in a fire. There is a
risk of an accident and injury.
Always replace faulty fuses with the speci-
fied new fuses having the correct amperage.
!Only use fuses that have been approvedfor Mercedes-Benz vehicles and which havethe correct fuse rating for the system con-cerned. Only use fuses marked with an "S".Otherwise, components or systems could bedamaged.
!Make sure that no moisture can enter thefuse box when the cover is open.
!When closing the cover, make sure that itis lying correctly on the fuse box. Moistureseeping in or dirt could otherwise impair theoperation of the fuses.
The fuses in your vehicle serve to close downfaulty circuits. If a fuse blows, all the compo-nents on the circuit and their functions stopoperating.
Blown fuses must be replaced with fuses ofthe same rating, which you can recognize bythe color and value. The fuse ratings, andother items of information to be complied withare, listed in the fuse allocation chart.
The fuse allocation chart is in the fuse box inthe front-passenger footwell (Ypage 302).
If a newly inserted fuse also blows, have thecause traced and rectified at a qualified spe-cialist workshop, e.g. an authorized Mercedes-Benz Center.
Before changing a fuse
XSecure the vehicle against rolling away(Ypage 145).
XSwitch off all electrical consumers.
XVehicles without KEYLESS-GO:removethe SmartKey from the ignition lock.
XVehicles with KEYLESS-GO start-func-tion or KEYLESS-GO:open the driver'sdoor.The vehicle electronics are now in positionZ. This is the same as the SmartKey beingremoved from the ignition.
The fuses are located in various fuse boxes:
RFuse box in the engine compartment on theleft-hand side of the vehicle, when viewed inthe direction of travel
RFuse box in the front-passenger footwell
Fuses301
Roadside Assistance
Z

Underinflated tires may:
Roverheat, leading to tire defects
Radversely affect handling
Rwear excessively and/or unevenly
Rhave an adverse effect on fuel consumption
Overinflated tires
GWARNING
Tires with excessively high pressure can
burst because they are damaged more eas-
ily by road debris, potholes etc. In addition,
they also suffer from irregular wear, which
can severely impair the braking properties
and the driving characteristics. There is a
risk of an accident.
Avoid tire pressures that are too high in all
the tires, including the spare wheel.
Overinflated tires may:
Rincrease the braking distance
Radversely affect handling
Rwear excessively and/or unevenly
Rhave an adverse effect on ride comfort
Rbe more susceptible to damage
Maximum tire pressures
CExample: maximum permissible tire pres-sure
Never exceed the maximum permissible tireinflation pressure. Always observe the recom-mended tire pressure for your vehicle whenadjusting the tire pressure (Ypage 307).
iThe actual values for tires are vehicle-spe-cific and may deviate from the values in theillustration.
Checking the tire pressures
Important safety notes
The tire pressure monitor does not warn youof:
Rincorrectly set tire pressure
Rsudden loss of tire pressure, e.g. from a for-eign object that has penetrated the tire
Observe the notes on tire pressure(Ypage 307).
Information on air pressure for the tires onyour vehicle can be found:
Ron the vehicle's Tire and Loading Informa-tion placard on the B-pillar
Rin the tire pressure table in the fuel filler flap(Ypage 144)
Rin the "Tire pressure" section
Checking tire pressures manually
To determine and set the correct tire pressure,proceed as follows:
XRemove the valve cap of the tire that is tobe checked.
XPress the tire pressure gauge securely ontothe valve.
XRead the tire pressure and compare it to therecommended value on the Tire and LoadingInformation placard or the tire pressuretable (Ypage 307).
XIf the tire pressure is too low, increase thetire pressure to the recommended value.
XIf the tire pressure is too high, release air.To do so, press down the metal pin in thevalve, using the tip of a pen for example.Then check the tire pressure again using thetire pressure checker.
XScrew the valve cap onto the valve.
XRepeat these steps for the other tires.
Tire pressure loss warning system
(Canada only)
General notes
While the vehicle is in motion, the tire pres-sure loss warning system monitors the set tirepressure using the rotational speed of thewheels. This enables the system to detect sig-nificant pressure loss in a tire. If the speed of
310Tire pressure
Wheels and tires

Observe the instructions and safety notes inthe display messages in the "Tires" section(Ypage 223).
If the wheel positions on the vehicle are rota-ted, the tire pressures may be displayed forthe wrong positions for a short time. This isrectified after a few minutes of driving, and thetire pressures are displayed for the correctpositions.
Restarting the tire pressure monitor
When you restart the tire pressure monitor, allexisting warning messages are deleted and thewarning lamps go out. The monitor uses thecurrently set tire pressures as the referencevalues for monitoring. In most cases, the tirepressure monitor will automatically detect thenew reference values after you have changedthe tire pressure. However, you can also setreference values manually as described here.The tire pressure monitor then monitors thenew tire pressure values.
XSet the tire pressure to the value recom-mended for the corresponding driving situa-tion on the Tire and Loading Informationplacard on the driver's sideB-pillar (Ypage 307).
You can find more tire pressure values forvarious operating conditions in the tire pres-sure table inside the fuel filler flap(Ypage 144).
XMake sure that the tire pressure is correcton all four wheels.
XMake sure that the SmartKey is in positionHin the ignition lock (Ypage 125).
XPressYoreon the steering wheelto select theServ.Serv.menu.
XPress thecordbutton to selectTire PressureTire Pressure.
XPress thevbutton.The multifunction display shows the currenttire pressure for each tire or theTireTirepressure will be displayed afterpressure will be displayed afterdriving a few minutesdriving a few minutesmessage.
XPress thedbutton.The multifunction display shows theUseUseCurrent Pressures as New ReferenceCurrent Pressures as New ReferenceValuesValuesmessage.
If you wish to confirm the restart:
XPress thevbutton.TheTire Press. Monitor RestartedTire Press. Monitor Restartedmessage appears in the multifunction dis-play.
After driving for a few minutes, the systemchecks whether the current tire pressuresare within the specified range. The new tirepressures are then accepted as referencevalues and monitored.
If you wish to cancel the restart:
XPress the8button.The tire pressure values stored at the lastrestart will continue to be monitored.
314Tire pressure
Wheels and tires

pounds per square inch (psi), in kilopascal(kPa) or in bar. The tire pressure should onlybe corrected when the tires are cold.
Cold tire pressure
The tires are cold:
Rif the vehicle has been parked with the tiresout of direct sunlight for at least three hoursand
Rif the vehicle has not been driven furtherthan 1 mile (1.6 km)
Tread
The part of the tire that comes into contactwith the road.
Bead
The tire bead ensures that the tire sitssecurely on the wheel. There are several steelwires in the bead to prevent the tire from com-ing loose from the wheel rim.
Sidewall
The part of the tire between the tread and thebead.
Weight of optional extras
The combined weight of those optional extrasthat weigh more than the replaced standardparts and more than 2.3 kg (5 lbs). Theseoptional extras, such as high-performancebrakes, level control, a roof rack or a high-per-formance battery, are not included in the curbweight and the weight of the accessories.
TIN (Tire Identification Number)
This is a unique identifier which can be usedby a tire manufacturer to identify tires, forexample for a product recall, and thus identifythe purchasers. The TIN is made up of themanufacturer's identity code, tire size, tiretype code and the manufacturing date.
Load bearing index
The load bearing index (also load index) is acode that contains the maximum load bearingcapacity of a tire.
Traction
Traction is the result of friction between thetires and the road surface.
Treadwear indicators
Narrow bars (tread wear bars) that are distrib-uted over the tire tread. If the tire tread is levelwith the bars, the wear limit of