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Air regulation overview
All pressure figures, temperature values and mass flows on
the intake air, charge air and exhaust lines of the engine are
measured. These values are used to regulate the charge
pressure, the cylinder filling and the exhaust gas recirculation rate. The advantage of this model is that the complex
air regulation system of the engine manages with a limited
number of sensors despite a large number of actuators.

The higher demands placed on exhaust gas after-treatment
in the future require an enhanced control and regulation
structure for both the air intake and exhaust of the engine.
The air regulation system of the engine is based on a model
that calculates conditions in all operational states of the
engine.

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Key:
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Intake Air Temperature Sensor G42
Charge air cooler
Charge Air Temperature Sensor after Charge Air
Cooler G811
Exhaust Gas Temperature Sensor 3 G495
Oxidizing catalytic converter
Heated Oxygen Sensor G39
Exhaust Gas Temperature Sensor 1 G235
Exhaust turbine with variable vanes
Wastegate By-pass Regulator Valve N75
Charge Pressure Actuator Position Sensor G581

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Exhaust Gas Temperature Sensor 4 G648
Differential Pressure Sensor G505
Diesel particulate filter
Exhaust Door Control Unit J883
Exhaust gas recirculation cooler
EGR Motor 2 V339
Turbocharger compressor
Mass Airflow Sensor G70
Throttle Valve Control Module J338
Charge Air Pressure Sensor G31

Turbocharger / exhaust manifold module
The turbocharger is integrated with the exhaust manifold
to form a single module. The turbocharger is equipped with
adjustable guide vanes (Variable Turbine Geometry) which
allows the flow of exhaust gas into the turbine impeller to
be regulated. The guide vanes are adjusted by an actuating
link operated by a vacuum motor.
The recirculated exhaust gases are not extracted at the
turbine housing, rather at the diesel particulate filter
outlet. The full mass flow is always channeled through the
turbocharger compressor by extracting the recirculated
exhaust gases downstream of the diesel particulate filter
outlet.

(Longitudinal installation shown)

The turbocharger operates with greater efficiency. This
allows higher charge pressures and higher volumetric
efficiency to be achieved at part loads in particular. A
benefit of this is the higher cooling capacity of the exhaust
gas recirculation system, which helps to reduce the mixing
temperature of the fresh air and recirculated exhaust
gases.
The acoustic characteristics of the exhaust turbocharger
were improved by using modified damping chambers in the
baffled sound absorber.

Vacuum motor

Vacuum connection
VTG actuating lever

Intake air from
air filter

Integral insulation

Exhaust manifold

Blow-by gases
of the positive
crankcase
ventilation
system

To intake
manifold

Oil return line

Positive Crankcase Ventilation
Heating Element N79

from EGR cooler
and EGR valve

Oil feed line

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Charge pressure control
Wastegate By-pass Regulator Valve N75
N75 is actuated by the engine control module using a duty
cycle (PWM). It switches the control pressure in the vacuum
motor to move the variable vanes of the turbocharger.
Effects of failure
The variable vanes of the turbocharger are moved to a
steep working position which results in a low charge pressure when the engine speed is low. The engine has less
power and active regeneration of the diesel particulate
filter is not possible.

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Intake Air Temperature Sensor G42
Charge Air Cooler
Charge Air Temperature Sensor after Charge Air Cooler G811
Exhaust Gas Temperature Sensor 1 G235
Exhaust Turbine with variable vanes
Wastegate By-pass Regulator Valve N75

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Charge Pressure Actuator Position Sensor G581
Turbocharger Compressor
Mass Airflow Sensor G70
Throttle Valve Control Module J338
Charge Air Pressure Sensor G31

Charge Air Pressure Sensor G31

Throttle Valve Control Module J338

Signal use

The throttle valve module is installed in the intake track
before the charge air cooler. There is an electric motor in
the throttle valve module that operates the throttle valve
via gears. Adjustment of the throttle valve is infinite and
can therefore be adapted to the respective engine operating situation. The position of the throttle valve is used to
regulate the air pressure and the intake air quantity in the
intake manifold. During regeneration of the diesel particulate filter, the throttle valve regulates the quantity of
intake air and therefore the oxygen supply. The valve is
closed when the engine is switched off. In this way, less air
is drawn in and compressed, which results in the engine
shutting down softly.

The signal from G31 allows the ECM to determine the air
pressure in the intake manifold and regulate charge pressure.
Effects of failure
There is no substitute function in the event of signal
failure. Charge air pressure regulation is shut off and there
is a significant reduction in engine output. The particulate
filter cannot be actively regenerated.

Intake Air Temperature Sensor G42

Effects of failure

Signal use

In the event of failure of the throttle valve module, correct
regulation of the intake manifold pressure is no longer
possible. There is no active regeneration of the diesel
particulate filter.

The signal from G42 is used by the ECM to regulate charge
pressure. Because temperature affects the density of the
charge air, the ECM uses the signal as a correction value.
Effects of failure
If G42 fails, the ECM uses a fixed substitute value for
calculation purposes.

Ambient Air Pressure Sensor
An ambient air pressure sensor is installed in the ECM. As
the density of the intake air decreases as altitude increases,
the air pressure is used as a correction value for charge
pressure control.

Charge Pressure Actuator Position
Sensor G581
Signal use
G581 provides the ECM with the position of the turbocharger variable guide vanes. In conjunction with G31, the
condition of the charge pressure regulation can be determined.

Throttle Position Sensor G69
G69 is integrated into the throttle valve module. The
sensor elements detect the current position of the throttle
valve.
Signal use
The ECM uses the signal to identify the current position of
the throttle valve in the intake manifold. This information
is required for regulation of the intake manifold pressure
and regeneration of the particulate filter.
Effects of failure
If the sensor fails, the engine will be run in emergency
mode with reduced power. No active regeneration of
the diesel particulate filter takes place.

Effects of failure
If G581 fails, the signal of the charge air pressure sensor
and the engine speed sensor are used by the ECM to determine the position of the guide vanes.

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Charge air cooler
A charge air cooler is integrated with the intake manifold.
This provides the following advantages:
•

The intake manifold temperatures are adjustable
within defined limits, the system can operate independently of the intake air temperature and the recirculated exhaust gas.

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A compact charge air circuit with reduced flow losses.

•

Icing and condensation are avoided in the charge air
cooler.

The charge air cooler operates according to the same principle as a heat exchanger.

Connecting flange

Charge air temperature sensor
after charge air cooler G811

Charge air cooler

Conduit
Charge air
pipe
Intake air temperature
sensor G42

Throttle valve control
module J338

Connection for charge
pressure sensor G31

Intake manifold temperature regulation
To regulate the intake manifold temperature to a specific
value, Charge Air Cooling Pump V188 is actuated by the
ECM based on the requirements. The duty cycle to actuate
the pump depends on the temperature measured by Charge
Air Temperature Sensor after Charge Air Cooler G811 and a
map in the ECM.
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Charge Air Temperature Sensor after
Charge Air Cooler G811

Charge Air Cooling Pump V188
Usage

Signal use
The signal from G811 is required:
•

•

to calculate the necessary duty cycle for actuating the
charge air cooling pump and therefore for regulating
the intake manifold temperature.
to protect components. If the air temperature in the
intake manifold exceeds a critical value, the engine
power is reduced.

V188 is actuated by the ECM with a PWM signal based on
engine requirements. It draws engine coolant from main
engine radiator and pumps it to the charge air cooler.

Effects of failure
If V188 fails, a DTC is logged in the ECM fault memory and
Malfunction Indicator Lamp K83 lights. If the intake manifold temperature exceeds a critical value, engine output is
reduced to protect components.

Effects of failure
In the event of sensor failure, the engine control unit
employs a fixed value for calculation purposes.

Intake Air Temperature Sensor G42
Signal use
G42 is used by the ECM to monitor the efficiency of the
charge air cooler. The temperatures from before and after
the cooler are compared by the ECM.

Effects of failure
If G42 fails, the ECM uses a fixed value for calculation purposes.

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Exhaust system
Longitudinally
mounted engines

Oxidizing catalytic converter
Exhaust Door Control Unit
J883

Center muffler

Diesel particulate filter
Flex tube

Oxidizing catalytic converter

Transversely mounted engines
Exhaust turbocharger

Exhaust manifold

EGR cooler

Diesel particulate filter

Flex tube

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Exhaust Door Control Unit
J883

Baffled rear mufflers

r

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Baffled rear mufler

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Exhaust gas treatment
Exhaust emission standards
In vehicles with BIN5 configurations, the Selective Catalytic
Reduction (SCR) system with cylinder pressure sensors in
the glow plugs is also installed. Also, in BIN 5 configuration Engine Coolant Temperature Sensor on Radiator Outlet
G83 is installed.

The chart on this page identifies the various emission
standards that are met with the EA 288 TDI engines on a
world-wide basis. In the United States the EA288 engines
will comply with the BIN5* Tier 2 standard.
Depending on the country applicable exhaust standard,
there are differences between components, both in terms
of type and how the exhaust gases enter the intake system.

Features

EU4

High pressure exhaust recirculation

x

Low pressure exhaust recirculation
Cooled exhaust recirculation valve

EU5

x
x

Uncooled exhaust recirculation valve

x

EU6

EU6 heavy duty

BIN51)/ULEV

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SCR system (AdBlue)
EGR cooler

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Additional temperature sensor at radiator
outlet

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4-way catalytic converter (modified coating on
the monoliths)

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Cylinder pressure sensor

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*The term "BIN" stems from the word "bag". During exhaust emission tests, the exhaust gases are collected in bags and
analyzed. Exhaust emission standards are ranked from BIN10 to BIN5.

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Exhaust gas recirculation
The BIN5 Tier 2 configuration of the engine uses both high
pressure and low pressure exhaust gas recirculation with a
cooled EGR valve and an EGR cooler. The EGR cooler has a
vacuum controlled by-pass flap actuated by the ECM
depending on operating temperatures.
Upstream of the turbocharger, the recirculated exhaust
gases flow through a port in the cylinder head and into a
water cooled exhaust gas recirculation valve mounted on
the distributor rail.
Distributor rail

The recirculated exhaust gases are divided among the
compressed air and the cooled charge air via the distributor
rail. This air mixture is channeled to the cylinder head
intake port.
The exhaust gas recirculation valve is powered by EGR
Motor V338. It is actuated by the ECM. The quantity of
recirculated exhaust gas is controlled by the stroke of the
valve. To provide protection from the high temperature
exhaust gas, the exhaust gas recirculation valve is cooled by
engine coolant.

EGR Motor V338

Water-cooled EGR valve

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Design of the exhaust gas recirculation (EGR) cooler
Vacuum connection

Vacuum cell

EGR bypass valve
Coolant return line
Uncooled/cooled
exhaust gases to
intake manifold

Exhaust gas inlet

Coolant feed line

Divider plate

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