warning light MERCEDES-BENZ CLA 2019 Repair Manual

Information on tire pressures is displayed in themultifunction display. After a few minutes ofdriving, the current tire pressure of each tire isshown in theServ.Serv.menu of the multifunctiondisplay, see illustration (example).
For information on the message display, refer tothe "Checking the tire pressure electronically"section (Ypage 299).
Important safety notes
GWARNING
Each tire, including the spare (if provided),
should be checked at least once every two
weeks when cold and inflated to the pressure
recommended by the vehicle manufacturer
on the Tire and Loading Information placard
on the driver's door B-pillar or the tire pres-
sure label on the inside of the fuel filler flap. If
your vehicle has tires of a different size than
the size indicated on the Tire and Loading
Information placard or, if available, the tire
pressure label, you should determine the
proper tire pressure for those tires.
As an added safety feature, your vehicle has
been equipped with a tire pressure monitoring
system (TPMS) that illuminates a low tire pres-
sure telltale when one or more of your tires
are significantly underinflated. Accordingly,
when the low tire pressure telltale lights up,
you should stop and check your tires as soon
as possible, and inflate them to the proper
pressure. Driving on a significantly underin-
flated tire causes the tire to overheat and can
lead to tire failure.
Underinflation also reduces fuel efficiency
and tire tread life, and may affect the vehicle's
handling and stopping ability. Please note that
the TPMS is not a substitute for proper tire
maintenance, and it is the driver's responsi-
bility to maintain correct tire pressure, even if
underinflation has not reached the level to
trigger illumination of the TPMS low tire pres-
sure telltale.
Your vehicle has also been equipped with a
TPMS malfunction indicator to indicate when
the system is not operating properly. The
TPMS malfunction indicator is combined with
the low tire pressure telltale. When the sys-
tem detects a malfunction, the warning lamp
will flash for approximately a minute and then
remain continuously illuminated. This
sequence will be repeated every time the vehi-
cle is started as long as the malfunction
exists. When the malfunction indicator is illu-
minated, the system may not be able to detect
or signal low tire pressure as intended.
TPMS malfunctions may occur for a variety of
reasons, including the installation of incom-
patible replacement or alternate tires or
wheels on the vehicle that prevent the TPMS
from functioning properly. Always check the
TPMS malfunction telltale after replacing one
or more tires or wheels on your vehicle to
ensure that the replacement or alternate Tires
and wheels allow the TPMS to continue to
function properly.
It is the driver's responsibility to set the tirepressure to that recommended for cold tireswhich is suitable for the operating situation(Ypage 293). Note that the correct tire pressurefor the current operating situation must first betaught-in to the tire pressure monitor. If a sub-stantial loss of pressure occurs, the warningthreshold for the warning message is aligned tothe taught-in reference values. Restart the tirepressure monitor after adjusting the pressure ofthe cold tires (Ypage 300). The current pres-sures are saved as new reference values. As aresult, a warning message will appear if the tirepressure drops significantly.
The tire pressure monitor does not warn you ofan incorrectly set tire pressure. Observe thenotes on the recommended tire pressure(Ypage 293).
The tire pressure monitor is not able to warn youof a sudden loss of pressure, e.g. if the tire ispenetrated by a foreign object. In the event of asudden loss of pressure, bring the vehicle to a
298Tire pressure
Wheels and tires

halt by braking carefully. Avoid abrupt steeringmovements.
The tire pressure monitor has a yellow warninglamp in the instrument cluster for indicatingpressure loss or a malfunction. Whether thewarning lamp flashes or lights up indicateswhether a tire pressure is too low or the tirepressure monitor is malfunctioning:
Rif the warning lamp is lit continuously, the tirepressure on one or more tires is significantlytoo low. The tire pressure monitor is not mal-functioning.
Rif the warning lamp flashes for around aminute and then remains lit constantly, thetire pressure monitor is malfunctioning.
In addition to the warning lamp, a messageappears in the multifunction display. Observethe information on display messages(Ypage 213).
It may take up to ten minutes for a malfunctionof the tire pressure monitor to be indicated. Amalfunction will be indicated by the tire pres-sure warning lamp flashing for approximatelyone minute and then remaining lit. When themalfunction has been rectified, the tire pressurewarning lamp goes out after a few minutes ofdriving.
The tire pressure values indicated by the on-board computer may differ from those meas-ured at a gas station with a pressure gauge. Thetire pressures shown by the on-board computerrefer to those measured at sea level. At highaltitudes, the tire pressure values indicated by apressure gauge are higher than those shown bythe on-board computer. In this case, do notreduce the tire pressures.
The operation of the tire pressure monitor canbe affected by interference from radio transmit-ting equipment (e.g. radio headphones, two-wayradios) that may be being operated in or near thevehicle.
Checking the tire pressure electroni-
cally
XMake sure that the SmartKey is in positionHin the ignition lock (Ypage 123).
XPressYoreon the steering wheel toselect theServ.Serv.menu.
XPress thecordbutton to selectTire PressureTire Pressure.
XPress thevbutton.The current tire pressure of each tire is shownin the multifunction display.
If the vehicle was parked for longer than20 minutes, theTire pressure will beTire pressure will bedisplayed after driving a few minutesdisplayed after driving a few minutesmessage is shown.
After a teach-in process, the tire pressure mon-itor automatically detects new wheels or newsensors. As long as a clear allocation of the tirepressure value to the individual wheels is notpossible, theTireTirePressurePressureMonitorMonitorActiveActivemessage is shown instead of the tire pressuredisplay. The tire pressures are already beingmonitored.
If an emergency spare wheel is mounted, thesystem may continue to show the tire pressureof the wheel that has been removed for a fewminutes. If this occurs, note that the value dis-played for the position where the spare wheel isfitted is not the same as the current tire pres-sure of the emergency spare wheel.
Tire pressure monitor warning mes-
sages
If the tire pressure monitor detects a pressureloss in one or more tires, a warning message isshown in the multifunction display. The yellowtire pressure warning lamp then lights up.
RIf thePlease Correct Tire PressurePlease Correct Tire Pressuremessage appears in the multifunction display,the tire pressure in at least one tire is too low.The tire pressure must be corrected when theopportunity arises.
RIf theCheck Tire PressureCheck Tire Pressuremessageappears in the multifunction display, the tirepressure in one or more tires has droppedsignificantly. The tires must be checked.
RIf theTireTirePressurePressureWarningWarningTireTireFail‐Fail‐ureuremessage appears, the tire pressure in oneor more tires has dropped suddenly. The tiresmust be checked.
Observe the instructions and safety notes in thedisplay messages in the "Tires" section(Ypage 213).
If the wheel positions on the vehicle are rotated,the tire pressures may be displayed for thewrong positions for a short time. This is rectifiedafter a few minutes of driving, and the tire pres-sures are displayed for the correct positions.
Tire pressure299
Wheels and tires
Z