Technical product information
Topic
Market area
Brand
Transaction No.
Level
Status
Release date

Bentayga - Stop Start System - Intermittent Failure
Bentley: worldwide (2WBE),Hongkong-Macau (5HK)
Bentley
2048860/1
EH
Approval

New customer code
Object of complaint

Complaint type

engine -> start/stop system -> engine stop by start/stop system
engine -> start/stop system -> engine start-up by start/stop system

functionality -> faulty
functionality -> faulty
functionality -> does not switch
off
functionality -> without function /
defect
functionality -> does not switch
on
functionality -> does not switch
off
functionality -> does not switch
off

engine -> start/stop system -> engine stop by start/stop system
engine -> start/stop system -> engine start-up by start/stop system
engine -> start/stop system -> engine start-up by start/stop system
engine -> start/stop system -> engine start-up by start/stop system
engine -> start/stop system -> engine stop by start/stop system -> engine stop start/stop system
when neutral position is detected
information, navigation, communication, entertainment -> symbolic control indicators -> start/stop
system indicator
information, navigation, communication, entertainment -> symbolic control indicators -> start/stop
system indicator
information, navigation, communication, entertainment -> symbolic control indicators -> start/stop
system indicator
information, navigation, communication, entertainment -> symbolic control indicators -> start/stop
system indicator
engine -> start/stop system -> engine stop by start/stop system
engine -> start/stop system -> engine stop by start/stop system
New workshop code
Object of complaint
Complaint type
Position
whole vehicle -> assemblies -> vehicle concept -> functionality concept error

Vehicle data
Bentayga
Sales types
Type MY Brand Designation Engine code Gearbox code Final drive code
4V1* 2017 E
*
*
*
4V1* 2018 E
*
*
*
Chasssis numbers
Manufacturer Filler Type Filler MY Factory From To
SJA

*

Documents
Document name
master.xml
startstop.pdf
startstop.docx

*

*

*

C

000001 999999

Prod from Prod to

functionality -> activates
functionality -> does not activate
functionality -> activates without
reason
functionality -> does not switch
off
functionality -> without function /
defect
functionality -> defective function
sequence

Position

Technical product information
Bentayga - Stop Start System - Intermittent Failure

Transaction No.: 2048860/1

Customer statement / workshop findings
“Start/Stop” system intermittently fails to operate.
The engine does not always stop or start automatically.
The following symbol is displayed on Driver Instrument Panel.

No faults relating to the “Start/Stop” system are present.

Technical background
There are a number of factors that prevent the “Start/Stop” system from automatically switching the engine off or on although the driver may
expect it.
It is possible that the “Start/Stop” system may start the engine automatically although the driver may not expect it.

Start Stop system Overview
The “Start-Stop” system can help to reduce fuel consumption and CO2 emissions.
The “Start-Stop” system is automatically activated with each ignition cycle and willswitch off the engine automatically when the vehicle stops, e.g. at
traffic lights.
The ignition remains on during this stop phase and the engine is automatically started on demand when the vehicle is ready to move off.
For the Start-Stop system to function, the following basic conditions must be met:
• The driver's door must be closed.
• The driver's safety belt must be fastened.
• The bonnet must be closed.
• The vehicle must have been moving at over 2 mph (4 km/h) since the last stop.
• The automatic gearbox must be in D-Drive, N-Neutral or P-Park.
The “Start-Stop” system is not available when any of the following Drive Dynamics modes have been selected: Sport, Snow & Grass, Dirt & Gravel,
Mud & Trail, Sand.
The “Start-Stop” system may also be inactive when the Custom profile has been selected, depending upon the settings applied to the Custom
profile.
The “Start-Stop” system willbe deactivated if any of the following occur: HillDescent Control, Electronic Stability Control (ESC) or All-Terrain mode are
activated, also when the Electronic Stability Control (ESC) system is switched off.
The “Start-Stop” willonly be active if the automatic gearbox is in D-Drive, N-Neutral, or P-Park.
The engine will start if the gear selector lever is moved to position R-Reverse during a stop phase.
It is possible to control whether or not the engine is switched off automatically by varying the amount of pressure on the brake pedal. For instance,
when braking gently in stop-and go traffic, the engine will remain on while the vehicle is at a standstill. As soon as the brake pedal is pressed harder, the
engine willswitch off.
The “Start-Stop” feature can start the engine if you leave the vehicle during a stop phase, provided you have left the vehicle for less than 30 seconds,
and the following conditions have been met:
• The driver's door is closed, the driver's safety belt is fastened and the brake pedal is depressed,
• or:
• The driver's door is closed, the brake pedal is depressed and a gear is engaged.
• Depress the brake pedal during a stop phase to prevent the vehicle from moving.
• If the engine “Start/Stop” button is pressed during a stop phase, the ignition will be switched off.

System limitations
The “Start-Stop” feature will behave differently depending upon the operating conditions of the vehicle.
If the symbol

is shown one or more of the following may apply.

• The engine has not reached the minimum temperature required for the Start-Stop system to operate.
• The temperature selected on the climate control system has not been reached.
• The exterior temperature is very high or low.
• The windscreen is being defrosted.
• The Park Assist function is switched on.
• The battery charge is too low.

• The steering wheel is close to full lock or the vehicle is being steered.
• R-Reverse has been selected.
• The vehicle is on a steep gradient.
• The vehicle is at high altitude.
The engine will start automatically during a stop phase if:
• The vehicle starts to roll (e.g. on a steep gradient).
• The interior temperature deviates from the climate control system setting.
• The windscreen is being defrosted.
• The brake pedal is pressed several times in succession.
• The battery charge drops to an insufficient level.
• Electrical power consumption is high.
The engine willswitch off when the conditions for Start-Stop mode are met.
To prevent the battery from being discharged, the ignition will be switched off automatically if:
• The Start-Stop system has switched off the engine,
and:
• The vehicle is stationary,
and:
• The driver has left the vehicle and the engine has not been restarted within approximately 30 seconds.
The message “Ignition will be switched off automatically” will be displayed in the driver instrument panel and the side lights will be switched on instead
of the dipped headlights.
After approximately 30 minutes, or when the vehicle is locked, the side lights will be switched off.
The ignition is also switched off if the vehicle is locked from the outside during a stop phase. If the Start-Stop system has not stopped the engine or if
you have switched off the Start-Stop system manually, the engine willcontinue running and the ignition willnot be switched off automatically.

Important
If D-Drive or N-Neutral are selected after selecting R-Reverse, the vehicle must have been moving at over 6 mph (10 km/h) before the system can
switch off the engine again.
Although the engine is switched off shortly before the vehicle comes to a halt, the foot brake servo and power steering will still function.

Production change
Not applicable.

Measure
With a Customer complaint of incorrect “Start/Stop” functionality, use Guided Fault Finding to interrogate for Diagnostic Trouble Codes (DTC’s) or
any concern that may be influencing the “Start/Stop” system.
If relevant DTC’s are not present and there are no other factors stopping the “Stop/Start” system from operating correctly, then the customer
should be informed that the “Stop/Start” system is operating correctly, any variation in “Start/Stop” operation is due to the complex nature of the
system and conditions that may affect its functionality.
A comprehensive list showing the various systems that may influence the “Start/Stop” system is attached.

Explanatory notes on history entries of the active devices
01 - Engine Electronics
Start requests
Reason
Engine temperature too low
Engine temperature too high
Brake vacuum too low
Immobilizer requests restart

SCR System requires restart

Engine hood open

Steering

Rolling vehicle

Auxiliary consumers power
too high

Hybrid battery power
insufficient

Cause:
The engine temperature fell
too low
The engine temperature rose
too high
Pressure in brake servo unit
too low, engine is started to
boost the braking power
It was detected that the key is
moving away from the vehicle
The temperature of one or
more component(s) of the SCR
catalytic converter system
is/are outside the regular
operating range.

Handling
Advise the customer that this
will help protect the engine
Advise the customer that this
will help protect the engine
Advise the customer that this
will improve safety

Advise the customer that this
will improve safety
Advise the customer that the
operational readiness of
emissions-related components
must always be ensured as a
legal requirement.
Advise the customer that
start/stop is disabled for his
Engine hood open
safety when the bonnet is open
(also in hybrid vehicle).
Advise the customer that for
Steering wheel is permanently
the engine to be stopped the
in motion while the driver
steering wheel must not be
comes to a stop and presses the
moving, because the steering
brake with sufficient force
assistance then has to be
(stop request)
maintained.
To provide the ancillary units
The vehicle will have no brake
(e.g. brake servo unit) with
servo assist, for example, if
mechanical energy, the
running without the
engines of vehicles with
combustion engine.
start/stop must always be on.
Various influences
(temperature/loading by
operation points) might cause
All comfort functions provided
the ancillary consumers to
by the ancillary consumers
develop an increased power
need to be maintained for the
demand which can/should no
customer.
longer be covered by the
battery alone.
Various influences
(temperature/loading by
Advise the customer that this
operation points) might restrict
protects the battery.
the battery's capability to selfprotect its power capacity.

If the battery is fully charged
by a lengthy recuperation
phase, for example, no more
electric thrust (simulation of
Deceleration takeover active
the combustion engine's thrust
by the electric motor) can be
set. To ensure a consistent
driving feel, the engine is then
activated and set at this thrust.
The engine must be run at
certain interval for a defined
Motor protection active
time in order to protect the
engine components.
To prevent the fuel from
clogging, due to inappropriate
consistency (cold), the fuel
Fuel clogging protection active
must be used up and
intermingled with topped-up
fuel.
The temperature of one or
more component(s) of the
Cat. heater
catalytic converter system
is/are outside the regular
operating range.
The engine needs to be
Intermittent function
running for adaptations and
restriction
diagnostics, as well as for
component protection
Restriction in start system
.
Stop prohibitions
Reason
Ambient air density/Ambient
air pressure
Brake vacuum / Brake vacuum
too low
Intermittent function
restriction

Bad start detection / Bad start
detection from starter control
Regeneration operation

Cause:
Ambient air density outside
nominal range
Pressure in brake servo unit
too low, engine must remain
on to boost the braking power
One of the following reasons
occurred:
Starter control sends stop
prohibition
Neutral not plausibilitychecked
Immobilizer active
Special speed controller
The restart took too long
One of the following diesel
exhaust components is in

Advise the driver of this
comfort feature. The vehicle
would otherwise disable
"engine braking" when driving
downhill.

Advise the customer that this
protects the engine
components.
Advise the customer that this
protects the engine
components and vehicle.
Advise the customer that the
operational readiness of
emissions-related components
must always be ensured as a
legal requirement.
Advise the customer that for
safe execution the engine must
not be stopped.
.

Handling
Advise the customer that this
will help protect the engine
Advise the customer that this
will improve safety
Advise the customer that this
will improve safety

Work through the relevant test
plan
Advise the customer that this
action deactivates the start-

regeneration mode:
Diesel particle filter
SCR system
NOx storage cat
Mixture adaption

Engine temperature too low
Engine temperature too high

SCR System requires restart

Engine hood open

Steering

Steering angle

Driving situation

Play protection
Function locked due to
excessive stalling

To balance out drift over the
service life in the fuel
metering system, the system
auto-adapts.
One or more engine
component(s) is/are outside
the regular operating range.
One or more engine
component(s) is/are outside
the regular operating range.
The temperature of one or
more component(s) of the SCR
catalytic converter system
is/are outside the regular
operating range.

stop function. Make frequent
trips to burn free the filter

Advise the customer that the
purpose of mixture adaption is
to ensure consistently safe and
comfortable running of the
engine.
Advise the customer that this
will help protect the engine
Advise the customer that this
will help protect the engine

Advise the customer that the
operational readiness of
emissions-related components
must always be ensured as a
legal requirement.
Advise the customer that
start/stop is disabled for his
Engine hood open
safety when the bonnet is
open.
Advise the customer that for
Steering wheel is permanently
the engine to be stopped the
in motion while the driver
steering wheel must not be
comes to a stop and presses the
moving, because the steering
brake with sufficient force
assistance then has to be
(stop request)
maintained.
Advise the customer that he
must not turn the steering
wheel to stop the engine. It is
Steering angle too wide.
assumed that a turn is needed
and the engine needs to be
running.
Advise the customer that the
system assumes the vehicle is
Manoeuvring detection (R
manoeuvring (e.g. parking).
engaged) is active
This typically requires the
engine to be running.
Advise the customer that, for
Too many engine starts in a
comfort reasons, the engine
standstill phase were
prevents stopping after
requested.
repeated starts in a standstill
phase.
If excessively frequent stalling Advise the customer that this
is detected, the coordinator
will help protect the engine

disables start/stop mode in
order to protect components
Brake pedal information,
plausibility

Tighter traffic flow detected

E machine, output too low

Rolling vehicle

Clutch protection K0

Auxiliary consumers power
too high

Adaption active

Hybrid battery power
insufficient

This function checks the brake
pedal sender for a plausible
signal.
The vehicle detects slowmoving traffic (frequent stops
at low speed) and enforces a
stop prohibition to prevent
short stops.
Various influences
(temperature/loading by
operation points) might restrict
the electric motor's capability
to self-protect its power
capacity
To provide the ancillary units
(e.g. brake servo unit) with
mechanical energy, the
engines of vehicles with
start/stop must always be on.
In some situations the
separating clutch must be
closed for its own protection,
necessitating running of the
engine.
Various influences
(temperature/loading by
operation points) might cause
the ancillary consumers to
develop an increased power
demand which can/should no
longer be covered by the
battery alone.
For legal reasons, and for
component protection, some
engine functions must be
regularly adapted. They
'relearn' or enhance the
ambient conditions for faultfree running.
Various influences
(temperature/loading by
operation points) might restrict
the battery's capability to selfprotect its power capacity.

Advise the driver that he must
have pressed and released the
brake pedal once before the
first stop.
Advise the driver of this
comfort feature

Advise the customer that this
protects the electric motor.

The vehicle will have no brake