Peugeot 405. Manual - part 33

b) Ensure that the mating surfaces of the

manifold and throttle body are clean and
dry, then fit a new gasket. Securely
tighten the throttle body retaining bolts.

c) Ensure that all hoses are correctly

reconnected and, where necessary, that
their retaining clips are securely
tightened.

d) On completion, adjust the accelerator

cable using the information given in
Section 4.

13 Fuel injection system -

testing and adjustment

3

Testing

1 If a fault appears in the fuel injection
system, first ensure that all the system wiring
connectors are securely connected and free
of corrosion. Ensure that the fault is not due to
poor maintenance; ie, check that the air
cleaner filter element is clean, the spark plugs
are in good condition and correctly gapped,
the valve clearances are correctly adjusted,
the cylinder compression pressures are
correct, the ignition timing is correct, and that
the engine breather hoses are clear and
undamaged, referring to Chapters 1, 2 and 5
for further information.
2 If these checks fail to reveal the cause of
the problem, the vehicle should be taken to a
Peugeot dealer for testing. A wiring block
connector is incorporated in the engine
management circuit, into which a special
electronic diagnostic tester can be plugged.
The connector is clipped to the rear of the
ECU mounting box. The tester will locate the
fault quickly and simply, alleviating the need
to test all the system components individually,
which is a time-consuming operation that also
carries a risk of damaging the ECU.

Adjustment

3 Experienced home mechanics with a
considerable amount of skill and equipment
(including a tachometer and an accurately
calibrated exhaust gas analyser) may be able
to check the exhaust CO level and the idle
speed. However, if these are found to be in
need of adjustment, the car must be taken to
a Peugeot dealer for further testing.
4 On the Fenix and Bosch systems, no
adjustment is possible. Should the idle speed
or exhaust gas CO level be incorrect, then a
fault must be present in the fuel injection
system.
5 On the Magneti Marelli system, it is
possible to adjust the mixture setting (exhaust
gas CO level) and ignition timing. However,
adjustments can be made only by re-
programming the ECU, using special
diagnostic equipment connected to the
system via the diagnostic connector.

14 Fenix system components -

removal and refitting

3

Throttle position sensor

1 Disconnect the battery negative lead, then
disconnect the wiring plug from the sensor.
2 Remove the two securing screws, then
carefully withdraw the sensor from the fuel
injection unit.
3 Refitting is a reversal of removal. No
adjustment of the sensor is possible. A self-
adjusting system is incorporated in the
electronic control unit.

Fuel injector

Note: Refer to the warning note in Section 1
before proceeding. If a faulty injector is
suspected, before condemning the injector, it
is worth trying the effect of one of the
proprietary injector-cleaning treatments.
4 Depressurise the fuel system with reference
to Section 8
5 Disconnect the battery negative lead.
6 Unscrew the two securing nuts, and
remove the air box from the top of the throttle
housing.
7 Release the securing clip and disconnect
the injector wiring plug.
8 Remove the screw securing the injector
retaining plate to the top of the fuel injection
unit, lift off the retainer, then withdraw the
injector.
9 Recover and discard the injector sealing
rings (check to ensure that new sealing rings
can be obtained before discarding the old
ones).
10 Refitting is a reversal of removal, bearing
in mind the following points.

a) Always renew both sealing rings, and

apply a smear of grease to each to ease
injector refitting.

b) Refit the injector so that its wiring

terminals point towards the front of the
vehicle, and locate the edge of the
retainer securely in the groove at the top
of the injector.

c) Before refitting the injector securing

screw, apply a few drops of locking fluid
to the threads.

d) On completion, switch on the ignition and

check carefully for signs of fuel leaks; if
any signs of leakage are detected, the
problem must be rectified before the
engine is started.

Idle speed control valve

11 Disconnect the battery negative lead, then
release the securing clip, and disconnect the
wiring plug from the valve.
12 Loosen the clamps, and disconnect the
two air hoses from the base of the valve,
noting their locations in relation to the flow
direction arrow marked on the valve body.
13 Loosen the two clamp nuts or bolts (as
applicable), then withdraw the valve (it may be

necessary to remove the clamp completely, to
provide sufficient clearance to remove the
valve).
14 Refitting is a reversal of removal, ensuring
that the valve is positioned correctly, with the
air hoses connected as noted before removal.

Fuel pressure regulator

15 The fuel pressure regulator (consisting of
a valve operated by a spring-loaded
diaphragm and a metal cover) is secured by
four screws to the top of the throttle housing.
Although the unit can be dismantled for
cleaning, if required (once the air box has
been removed for access), it should not be
disturbed unless absolutely necessary.
16 At the time of writing, it was not clear
whether the pressure regulator components
were available separately from the complete
throttle housing.
17 Always depressurise the fuel system
before disturbing any components. If the
regulator cover is removed, note its
orientation on the throttle housing before
removal, to ensure correct refitting.

Inlet air temperature sensor

18 The sensor is screwed into the top of the
inlet manifold.
19 Disconnect the battery negative lead.
20 Release the securing clip, and disconnect
the wiring plug from the sensor.
21 Unscrew the sensor and withdraw it.
22 Refitting is a reversal of removal.

Manifold absolute pressure
(MAP) sensor

23 The sensor is mounted on the body front
panel.
24 Disconnect the battery negative lead, then
release the securing clip and disconnect the
wiring plug from the sensor.
25 Disconnect the vacuum hose from the
sensor.
26 Unscrew the two securing nuts, or bolts
(as applicable), then withdraw the sensor from
the body front panel.
27 Refitting is a reversal of removal.

Coolant temperature sensor

28 Disconnect the electrical plug from the
sensor on the water housing.
29 Drain the cooling system as described in
Chapter 1.
30 Unscrew the sensor from the water
housing.
31 Refit in the reverse order using a new
sealing washer, then top-up and bleed the
cooling system with reference to Chapter 1.

Engine speed/position sensor

32 Disconnect the wiring lead and release it
from the clips.
33 Unscrew the bolt and withdraw the sensor
from the engine.
34 Refitting is a reversal of removal. It is not
possible to adjust the position of the sensor.

4B•6 Fuel/exhaust systems - single-point fuel injection models

15 Bosch Monopoint system

components - removal and
refitting

3

Note: Check the availability of individual
components with your Peugeot dealer before
dismantling.

Fuel injector

Note: Refer to the warning note in Section 1
before proceeding. If a faulty injector is
suspected, before condemning the injector, it
is worth trying the effect of one of the
proprietary injector-cleaning treatments.
1 Remove the inlet air temperature sensor as
described later in this Section.
2 Lift out the injector and recover its lower
sealing ring.
3 Refitting is a reversal of the removal
procedure ensuring that the injector sealing
ring(s) and injector cap O-ring are in good
condition. When refitting the injector cap
ensure that the injector pins are aligned with
the cap terminals, the terminals are marked “+”
and “-” for identification (see illustrations).

Fuel pressure regulator

Note: Refer to the warning note in Section 1
before proceeding. At the time of writing, the
fuel pressure regulator assembly was not
available separately from the throttle body
assembly. Refer to a Peugeot dealer for the
latest information. Although the unit can be
dismantled for cleaning, if required, it should
not be disturbed unless absolutely necessary.
4 Disconnect the battery negative terminal.
5 Remove the air cleaner-to-throttle body
duct, using the information given in Section 2.
6 Using a marker pen, make alignment marks
between the regulator cover and throttle
body, then slacken and remove the cover
screws (see illustration). As the screws are
slackened, place a clean rag over the cover to
catch any fuel spray which may be released.
7 Lift off the cover, then remove the spring
and withdraw the diaphragm, noting its
correct fitted orientation. Remove all traces of
dirt and examine the diaphragm for signs of
splitting. If damage is found, it will probably
be necessary to renew the throttle body
assembly.

8 Refitting is a reverse of the removal
procedure, ensuring that the diaphragm and
cover are fitted the correct way round, and
that the retaining screws are securely
tightened.

Idle control stepper motor

9 Disconnect the battery negative terminal.
10 Depress the retaining clip and disconnect
the wiring connector from the idle control
stepper motor.
11 Undo the retaining screws and remove
the motor from the front of the throttle body
(see illustration).
12 Refitting is a reverse of the removal
procedure, ensuring that the motor retaining
screws are securely tightened.

Throttle potentiometer

13 The throttle potentiometer is a sealed unit,
and  under no circumstances should it be

disturbed. For this reason, on some models, it
is secured to the throttle body assembly by
tamperproof screws. If the throttle
potentiometer is faulty, the complete throttle
body assembly must be renewed - refer to
your Peugeot dealer for the latest information.

Inlet air temperature sensor

Note: Refer to the warning note in Section 1
before proceeding.
14 The inlet air temperature sensor is an
integral part of the throttle body injector cap.
To remove the cap, first disconnect the
battery negative terminal, then remove the air
cleaner-to-throttle body duct using the
information given in Section 2.
15 Undo the three retaining screws and
remove the circular plastic ring from the top of
the throttle body and recover its sealing ring
(see illustrations).
16 Depress the retaining clip and disconnect

Fuel/exhaust systems - single-point fuel injection models  4B•7

15.3c  On refitting, ensure cap terminals

are aligned with injector pins (arrowed)

15.15a  Undo the three retaining screws

(arrowed) . . .

15.11  Idle control stepper motor 

retaining screws (arrowed)

15.6  Fuel pressure regulator 

retaining screws (arrowed)

15.3b  . . . then lift off the cap and withdraw

the injector

15.3a  Undo the injector cap screw, noting

the use of rag to catch fuel spray . . .

4B

15.15b  . . . then lift off the plastic ring and

recover the sealing ring

the wiring connector from the injector wiring
connector (see illustration).
17 Undo the injector cap retaining screw,
then lift off the cap and recover the gasket
and/or sealing ring (as applicable). Note that
as the cap screw is slackened, place a rag
over the injector to catch any fuel spray which
may be released.
18 Refitting is a reversal of the removal
procedure ensuring that the injector cap
gasket and/or O-ring is in good condition.
Take care to ensure that the cap terminals are
correctly aligned with the injector pins and
securely tighten the cap retaining screw.

Coolant temperature sensor

19 Refer to Chapter 3.

Electronic control unit (ECU)

20 The ECU is located in the plastic box
which is mounted onto the rear of the battery
mounting tray.
21 To remove the ECU, first disconnect the
battery.
22 Unclip the cover from the box, then lift the
retaining clip and disconnect the wiring
connector from the ECU.
23 Undo the retaining nut and release the
relay unit from the rear of the ECU box.
24 Undo the retaining screws and remove
the ECU and box assembly from the battery
tray. If necessary, undo the retaining screws
and separate the ECU and box.
25 Refitting is a reverse of the removal
procedure ensuring that the wiring connector
is securely reconnected.

Fuel injection system relay unit

26 The relay unit is mounted onto the rear of
the ECU plastic box which is situated directly
behind the battery.
27 To remove the relay unit, first disconnect
the battery.
28 Undo the retaining nut, then disconnect
the wiring connector and remove the relay unit
from the vehicle.
29 Refitting is the reverse of removal,
ensuring that the relay unit is securely clipped
in position.

Crankshaft sensor

30 The crankshaft sensor is situated on the
front face of the transmission (clutch) housing.

31 To remove the sensor, first disconnect the
battery negative terminal.
32 Trace the wiring back from the sensor to
the wiring connector, and disconnect it from
the main harness.
33 Prise out the rubber grommet, then undo
the retaining bolt and withdraw the sensor
from the transmission.
34 Refitting is a reverse of the removal
procedure. Ensure that the sensor retaining
bolt is securely tightened, and that the
grommet is correctly seated in the
transmission housing.

Vehicle speed sensor

35 The vehicle speed sensor is an integral
part of the speedometer drive housing. Refer
to Chapter 7A, Section 7 for removal and
refitting details.

16 Magneti Marelli system

components - removal and
refitting

3

Note: Check the availability of individual
components with your Peugeot dealer before
dismantling.

Fuel injector

Note: Refer to the warning note in Section 1
before proceeding.
Note: If a faulty injector is suspected, before
condemning the injector, it is worth trying the
effect of one of the proprietary injector-
cleaning treatments. If this fails, the vehicle
should be taken to a Peugeot dealer for
testing using the appropriate specialist
equipment. At the time of writing, it appears
that neither the fuel injector nor its seals are
available separately and, if faulty, the
complete upper throttle body assembly must
be renewed. Refer to your Peugeot dealer for
further information on parts availability.
1 Disconnect the battery negative terminal.
2 Remove the air cleaner-to-throttle body
duct using the information given in Section 2.
3 Release the retaining tangs and disconnect
the injector wiring connector (see
illustration).
4 Undo the retaining screw, then remove the
retaining clip and lift the injector out of the

housing, noting its sealing ring. Note that as
the screw is slackened, place a rag over the
injector to catch any fuel spray which may be
released.
5 Refitting is a reverse of the removal
procedure ensuring that the injector sealing
ring is in good condition.

Fuel pressure regulator

Note: Refer to the warning note at the start of
this Section before proceeding.
Note: At the time of writing, it appears that the
fuel pressure regulator is not available
separately. If the fuel pressure regulator
assembly is faulty, the complete upper throttle
body assembly must be renewed. Refer to a
Peugeot dealer for further information on parts
availability. Although the unit can be
dismantled for cleaning, if required, it should
not be disturbed unless absolutely necessary.
6 Disconnect the battery negative terminal.
7 Remove the air cleaner-to-throttle body
duct using the information given in Section 2.
8 Using a suitable marker pen, make
alignment marks between the regulator cover
and throttle body, then undo the four retaining
screws. Note that as the screws are
slackened, place a rag over the cover to catch
any fuel spray which may be released.
9 Lift off the cover, then remove the spring
and withdraw the diaphragm whilst noting its
correct fitted orientation. Remove all traces of
dirt and examine the diaphragm for splitting. If
damage is found, it will be necessary to renew
the complete upper throttle body assembly as
described earlier in this Section.
10 Refitting is a reverse of the removal
procedure ensuring that the diaphragm and
cover are fitted the correct way around and
the retaining screws are securely tightened.

Idle control stepper motor

11 Disconnect the battery negative terminal.
12 To remove the stepper motor, depress the
retaining tabs and disconnect the wiring
connector. Undo the two retaining screws and
withdraw the motor from the side of the
throttle body assembly.
13 Refitting is a reverse of removal.

Throttle potentiometer

14 Disconnect the battery negative terminal,
then depress the retaining tabs and
disconnect the wiring connect from the
throttle potentiometer (see illustration).
15 Undo the two retaining screws and
remove the throttle potentiometer from the
side of the throttle body assembly.
16 Refitting is a reversal of the removal
procedure ensuring that the throttle
potentiometer tang is correctly engaged with
the throttle spindle.

Inlet air temperature sensor

17 The inlet air temperature sensor is
screwed into the underside of the upper
throttle body where it is situated on the left-
hand side of the fuel injector.

4B•8 Fuel/exhaust systems - single-point fuel injection models

15.16  Disconnecting the injector wiring

connector. Injector screw is arrowed

16.3  Injector wiring connector (arrowed)

18 To remove the sensor, first disconnect the
battery negative terminal.
19 Disconnect the wiring connector, then
undo the retaining screw and remove the inlet
air temperature sensor from the throttle body.
Note: The sensor retaining screw is very
difficult to reach. If it proves impossible to
unscrew, the throttle body will have to be
removed to permit sensor removal.
20 Refitting is a reverse of removal.

Manifold absolute pressure
(MAP) sensor

21 The MAP sensor is mounted onto a
bracket which is situated on the engine
compartment bulkhead, behind the throttle
body.
22 To remove the sensor, first disconnect the
battery negative terminal.
23 Slacken and remove the three retaining
bolts, then free the MAP sensor from the
bracket. Disconnect the wiring connector and
vacuum hose and remove the sensor from the
engine compartment.
24 Refitting is a reversal of the removal
procedure.

Coolant temperature sensor

25 Refer to Chapter 3.

Crankshaft sensor

26 Refer to Section 14.

Electronic control unit (ECU)

27 Refer to Section 14.

Fuel injection system relay unit

28 Refer to Section 14.

Throttle body heating element

29 The throttle body heating element is
situated in the front of the throttle body.
30 To remove the element, first disconnect
the battery negative terminal.
31 Remove the air cleaner housing-to-
throttle body duct using the information given
in Section 2.
32 Disconnect the wiring connectors from
the inlet air temperature sensor and the
injector. Also disconnect the main wiring
connector from the throttle body and free the
connector from its mounting bracket.
33 Undo the retaining screws and free the
accelerator mounting bracket from the throttle
body. As the bracket is released, recover the
spring from the front of the heating element.
34 Ease the heating element out from the
throttle housing and remove it along with the
wiring connector and wiring harness. Examine
the O-ring for signs of damage or
deterioration and renew if necessary.
35 Refitting is a reversal of removal; where
necessary, use a new O-ring.

17 Inlet manifold - 

removal and refitting

3

Removal

1 Remove the throttle body (Section 12).
2 Drain the cooling system (see Chapter 1).
3 Slacken the retaining clip and disconnect
the coolant hose(s) from the manifold.
4 Slacken the retaining clip and disconnect
the vacuum servo unit hose from the left-hand
side of the manifold.
5 Make a final check that all the necessary
vacuum/breather hoses have been
disconnected from the manifold.
6 Unscrew the retaining nuts, then
manoeuvre the manifold away from the head
and out of the engine compartment. Note that
there is no manifold gasket.

Refitting

7 Refitting is the reverse of the removal
procedure, noting the following points:

a) Ensure that the manifold and cylinder

head mating surfaces are clean and dry,
and apply a thin coating of suitable

sealing compound to the manifold mating
surface. Refit the manifold and tighten its
retaining nuts to the specified torque.

b) Ensure that all relevant hoses are

reconnected to their original positions and
securely held (where necessary) by their
retaining clips.

c) Refit the throttle body as described in

Section 12.

d) On completion, refill the cooling system

as described in Chapter 1.

18 Exhaust manifold - 

removal and refitting

3

Removal

1 Refer to Chapter 4A, Section 15, noting that
the lambda (oxygen) sensor wiring connectors
should be disconnected. Alternatively, care
must be taken to support the front pipe, to
avoid any strain being placed on the sensor
wiring.

Refitting

2 Refitting is the reverse of the removal
procedure, noting the following points:

a) Examine all the exhaust manifold studs for

signs of damage and corrosion; remove
all traces of corrosion, and repair or
renew any damaged studs.

b) Ensure that the manifold and cylinder

head sealing faces are clean and flat, and
fit the new manifold gaskets. Tighten the
manifold retaining nuts to the specified
torque.

c) Reconnect the front pipe to the manifold.

19  Exhaust system - 

general information, removal
and refitting

3

Refer to Chapter 4A, Section 16, however

note that it will be necessary to disconnect
the lambda (oxygen) sensor wiring connectors
in order to remove the front pipe/complete
system. On refitting, ensure that the sensor
wiring is retained by all the relevant retaining
clips so that it is in no danger of contacting
the hot exhaust/engine.

Fuel/exhaust systems - single-point fuel injection models  4B•9

4B

16.14  Throttle potentiometer wiring

connector (arrowed)