Peugeot 405. Manual - part 37

gasket from the head, and discard it - a new
one must be used on refitting.
14 Examine the assembly, checking that the
butterfly valves open freely and close
smoothly. If not, the assembly must be
renewed. The only components available
separately are the vacuum diaphragm units -
if either one is faulty, it must be renewed as
described below.
15 Refitting is a reverse of the removal
procedure, noting the following points:

a) Ensure that the valve assembly and

cylinder head mating surfaces are clean
and dry, and fit the new manifold gasket
over the studs. Refit the valve assembly,
and securely tighten its retaining nuts and
bolts.

b) Ensure that all relevant hoses are

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

c) Refit the inlet manifold as described in

Section 18.

d) On completion, check the operation of

the ACAV system as described above.

Vacuum diaphragm unit

16 Disconnect the vacuum hose from the

diaphragm unit. Using a suitable flat-bladed
screwdriver, carefully lever the unit pushrod
off the valve linkage balljoint (see
illustration).
17 Slacken and remove the two bolts
securing the diaphragm unit mounting bracket
to the valve assembly, and remove the
diaphragm from the engine.
18 Refitting is a reversal of the removal
procedure, ensuring that the diaphragm
pushrod is clipped firmly onto the linkage
balljoint.

Solenoid valve

19 The solenoid control valve is mounted on
the left-hand end of the cylinder head 
(see illustration). Before removing the valve, 
first disconnect the battery negative terminal,
and position it away from the battery.
20 Depress the retaining clip, and disconnect
the wiring connector from the valve.
21 Undo the nut securing the valve to the
cylinder head, then withdraw the valve,
disconnecting its vacuum hoses as they
become accessible.
22 Refitting is a reversal of the removal
procedure. Test the system on completion, as
described above.

20 Exhaust manifold - 

removal and refitting

2

Removal

1 Refer to Chapter 4A, Section 15, noting that
where applicable 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. Where
applicable, jack up the front of the car and
support on axle stands (see “Jacking and
Vehicle Support”).

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 nuts to the specified torque.

c) Reconnect the front pipe to the manifold

using the information given in Section 18.

21 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 - multi-point fuel injection models  4C•13

19.19  ACAV solenoid valve 

retaining nut (1), wiring connector (2) 

and hose connections (3)

19.16  ACAV vacuum diaphragm unit

4C

4D

Chapter 4  Part D:
Emission control systems

Catalytic converter - general information and precautions  . . . . . . . . .3
Emission control system check . . . . . . . . . . . . . . . . . . . .See Chapter 1

Emission control systems - testing and component renewal . . . . . . . .2
General information  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1

4D•1

Easy, suitable for
novice with little
experience

Fairly easy, suitable
for beginner with
some experience

Fairly difficult,
suitable for competent
DIY mechanic

Difficult, suitable for
experienced  DIY
mechanic

Very difficult,
suitable for expert
DIY or  professional

Degrees of difficulty

Contents

1

General information

1 All models have various built-in fuel system
features which help to minimise emissions,
and all models have at least the crankcase
emission-control system described below.
Models with a catalytic converter are also
fitted with the exhaust and evaporative
emission control systems.
2 Most models are able to run on 95 RON
unleaded fuel, but the following early engines
must use 97 RON leaded fuel. However it may
be possible to use unleaded fuel if the ignition
is retarded by 3° - check with your Peugeot
dealer.

a) TU3 (K1A)
b) TU3A (K1G)
c) XU92C (D2D)
d) XU9J2 (D6A)
e) XU9J4 (D6C)
f) XU52C (B2A)

Crankcase emission control

3 To reduce the emission of unburned
hydrocarbons from the crankcase into the
atmosphere, the engine is sealed, and the
blow-by gases and oil vapour are drawn from
the crankcase, through a wire-mesh oil
separator, into the inlet tract, to be burned by
the engine during normal combustion.
4 Under conditions of high manifold
depression (idling, deceleration) the gases will
be sucked positively out of the crankcase.
Under conditions of low manifold depression
(acceleration, full-throttle running) the gases
are forced out of the crankcase by the
(relatively) higher crankcase pressure; if the
engine is worn, the raised crankcase pressure
(due to increased blow-by) will cause some of
the flow to return under all manifold
conditions.

Exhaust emission control

5 To minimise the amount of pollutants which
escape into the atmosphere, some models

are fitted with a catalytic converter in the
exhaust system. On all models where a
catalytic converter is fitted, the system is of
the “closed-loop” type; a lambda (oxygen)
sensor in the exhaust system provides the fuel
injection/ignition system ECU with constant
feedback, enabling the ECU to adjust the
mixture to provide the best possible
conditions for the converter to operate.
6 The lambda sensor has a built-in heating
element, controlled by the ECU through the
lambda sensor relay, to quickly bring the
sensor’s tip to an efficient operating
temperature. The sensor’s tip is sensitive to
oxygen, and sends the ECU a varying voltage
depending on the amount of oxygen in the
exhaust gases. If the inlet air/fuel mixture is
too rich, the exhaust gases are low in oxygen,
so the sensor sends a low-voltage signal. The
voltage rises as the mixture weakens and the
amount of oxygen in the exhaust gases rises.
Peak conversion efficiency of all major
pollutants occurs if the inlet air/fuel mixture is
maintained at the chemically-correct ratio for
the complete combustion of petrol - 14.7
parts (by weight) of air to 1 part of fuel (the

“stoichiometric” ratio). The sensor output
voltage alters in a large step at this point, the
ECU using the signal change as a reference
point, and correcting the inlet air/fuel mixture
accordingly by altering the fuel injector pulse
width (the length of time that the injector is
open).

Evaporative emission control

7 To minimise the escape into the
atmosphere of unburned hydrocarbons, an
evaporative emissions control system is fitted
to later models (see illustration). The fuel
tank filler cap is sealed, and a charcoal
canister, mounted underneath the front left-
hand wing, collects the petrol vapours
generated in the tank when the car is parked.
The canister stores them until they can be
cleared from the canister (under the control of
the fuel injection/ignition system ECU) via the
purge solenoid valve. When the valve is
opened, the fuel vapours pass into the inlet
tract, to be burned by the engine during
normal combustion.
8 To ensure that the engine runs correctly
when it is cold and/or idling, the ECU does not

1.7  Evaporative emissions control system

1  Fuel filler cap
2  Charcoal canister
3  Hose

4  Calibrated orifice
5  Hose
6  Solenoid valve

7  Coolant temperature 

sensor

10  Safety valve

open the purge control valve until the engine
has warmed up and is under load; the valve
solenoid is then modulated on and off, to
allow the stored vapour to pass into the inlet
tract.

2

Emission control systems -
testing and component
renewal

2

Crankcase emission control

1 The components of this system require no
routine attention, other than to check that the
hoses are clear and undamaged at regular
intervals.

Evaporative emission control

Testing

2 If the system is thought to be faulty,
disconnect the hoses from the charcoal
canister and purge control valve, and check
that they are clear by blowing through them. If
the purge control valve or charcoal canister
are thought to be faulty, they must be
renewed.

Charcoal canister - renewal

3 Jack up the front of the car and support on
axle stands (see “Jacking and Vehicle
Support”). Remove the left-hand front wheel.
4 Remove the left-hand front wheel arch liner
with reference to Chapter 11.
5 Disconnect the hoses from the canister,
noting their locations to ensure correct
refitting.
6 Unscrew the clamp bolt, and lift the
canister from its clamp on the body panel.
Alternatively, the complete clamp
bracket/canister assembly can be removed if
desired. Store or dispose of the canister
carefully - it may contain fuel vapour.
7 Refitting is a reversal of removal, but ensure
that the hoses are correctly reconnected as
noted before removal.

Purge valve(solenoid valve) - renewal

8 The purge valve is located in the hose
running from the carbon canister to the
throttle body/inlet manifold. The valve may be
mounted on a bracket, or may simply be
attached to the hoses, depending on model.

9 To remove the valve, first disconnect the
battery negative lead.
10 Where applicable, unbolt the valve
bracket, then disconnect the wiring plug.
11 Disconnect the hoses from the valve,
noting their locations to ensure correct
refitting, then withdraw the valve.
12 Refitting is a reversal of removal, ensuring
that the hoses are correctly reconnected, as
noted before removal.

Exhaust emission control

Testing

13 The performance of the catalytic
converter can be checked only by measuring
the idle mixture setting (exhaust gas CO
content) using an accurately calibrated
exhaust gas analyser.
14 If the CO level at the tailpipe is too high,
the vehicle should be taken to a Peugeot
dealer so that the complete fuel injection and
ignition systems, including the lambda sensor,
can be thoroughly checked using the special
diagnostic equipment.
15 Once this has been done, any fault must
lie in the catalytic converter, which should be
renewed as described below.

Catalytic converter - renewal

16 Refer to Part A of this Chapter, for the
centre silencer.

Lambda sensor - renewal

Note: The lambda sensor is fragile, and will
not work if it is dropped or knocked, if its
power supply is disrupted, or if any cleaning
materials are used on it.
17 According to model the Lambda sensor is
located either in the exhaust downpipe or in
the exhaust centre section.
18 Where necessary, jack up the front of the
car and support on axle stands (see “Jacking
and Vehicle Support”).
19 Trace the wiring back from the lambda
sensor to the connector and disconnect it.
20 Unscrew the sensor and remove it along
with its sealing washer.
21 Refitting is a reversal of the removal
procedure, using a new sealing washer.
Ensure that the sensor is securely tightened.
Check that the wiring is correctly routed, and
in no danger of contacting either the exhaust
system or the engine.

3

Catalytic converter - general
information and precautions

The catalytic converter is a reliable and

simple device, which needs no maintenance
in itself, but there are some facts of which an
owner should be aware, if the converter is to
function properly for its full service life.

a) DO NOT use leaded petrol in a car

equipped with a catalytic converter - the
lead will coat the precious metals,
reducing their converting efficiency, and
will eventually destroy the converter.

b) Always keep the ignition and fuel systems

well-maintained in accordance with the
manufacturer’s schedule.

c) If the engine develops a misfire, do not

drive the car at all (or at least as little as
possible) until the fault is cured.

d) DO NOT push- or tow-start the car - this

will soak the catalytic converter in
unburned fuel, causing it to overheat
when the engine does start.

e) DO NOT switch off the ignition at high

engine speeds.

f) DO NOT use fuel or engine oil additives -

these may contain substances harmful to
the catalytic converter.

g) DO NOT continue to use the car if the

engine burns oil to the extent of leaving a
visible trail of blue smoke.

h) Remember that the catalytic converter

operates at very high temperatures. DO
NOT, therefore, park the car in dry
undergrowth, or over long grass or piles
of dead leaves after a long run.

i) Remember that the catalytic converter is

FRAGILE - do not strike it with tools
during servicing work.

j) In some cases, a sulphurous smell (like

that of rotten eggs) may be noticed from
the exhaust. This is common to many
catalytic converter-equipped cars, and
once the car has covered a few thousand
miles the problem should disappear.

k) The catalytic converter, used on a well-

maintained and well-driven car, should
last for between 50 000 and 100 000
miles - if the converter is no longer
effective, it must be renewed.

4D•2 Emission control systems

5A

System type

 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

12-volt, negative earth

Battery

Type

 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Fulmen, Delco or Steco

Charge condition:

Poor

 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

12.5 volts

Normal  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

12.6 volts

Good  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

12.7 volts

Alternator

Type

 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Valeo, Bosch or Mitsubishi (depending on model)

Starter motor

Type

 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Valeo or Bosch (depending on model)

Chapter 5  Part A:
Starting and charging systems

Alternator drivebelt - removal, refitting and tensioning  . . . . . . . . . . . .6
Alternator - removal and refitting  . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
Alternator - testing and overhaul  . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
Battery check  . . . . . . . . . . . . . . . . . . . . . . . . . . . .See “Weekly checks”
Battery - removal and refitting  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
Battery - testing and charging  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3
Charging system - testing  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
Electrical fault-finding - general information . . . . . . . . . . . . . . . . . . . . .2
Electrical system check  . . . . . . . . . . . . . . . . . . . .See “Weekly checks”

General information and precautions  . . . . . . . . . . . . . . . . . . . . . . . . . .1
Ignition switch - removal and refitting  . . . . . . . . . . . . . . . . . . . . . . . .12
Oil level sensor - removal and refitting  . . . . . . . . . . . . . . . . . . . . . . . .14
Oil pressure warning light switch - removal and refitting  . . . . . . . . . .13
Oil temperature sensor - removal and refitting . . . . . . . . . . . . . . . . . .15
Starter motor - removal and refitting  . . . . . . . . . . . . . . . . . . . . . . . . .10
Starter motor - testing and overhaul  . . . . . . . . . . . . . . . . . . . . . . . . .11
Starting system - testing  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9

5A•1

Easy, suitable for
novice with little
experience

Fairly easy, suitable
for beginner with
some experience

Fairly difficult,
suitable for competent
DIY mechanic

Difficult, suitable for
experienced  DIY
mechanic

Very difficult,
suitable for expert
DIY or  professional

Degrees of difficulty

Specifications

Contents

1

General information and
precautions

General information

The engine electrical system consists

mainly of the charging and starting systems.
Because of their engine-related functions,
these components are covered separately
from the body electrical devices such as the
lights, instruments, etc (which are covered in
Chapter 12). Refer to Part B for information on
the ignition system.

The electrical system is of the 12-volt

negative earth type.

The battery is of the low maintenance or

“maintenance-free” (sealed for life) type and is
charged by the alternator, which is belt-driven
from the crankshaft pulley.

The starter motor is of the pre-engaged

type incorporating an integral solenoid. On

starting, the solenoid moves the drive pinion
into engagement with the flywheel ring gear
before the starter motor is energised. Once
the engine has started, a one-way clutch
prevents the motor armature being driven by
the engine until the pinion disengages from
the flywheel.

Precautions

Further details of the various systems are

given in the relevant Sections of this Chapter.
While some repair procedures are given, the
usual course of action is to renew the
component concerned. The owner whose
interest extends beyond component renewal
should obtain a copy of the “Automobile
Electrical & Electronic Systems Manual”,
available from the publishers of this manual.

It is necessary to take extra care when

working on the electrical system to avoid
damage to semi-conductor devices (diodes
and transistors), and to avoid the risk of
personal injury. In addition to the precautions

given in “Safety first!” at the beginning of this
manual, observe the following when working
on the system:

Always remove rings, watches, etc before

working on the electrical system. Even with
the battery disconnected, capacitive
discharge could occur if a component’s live
terminal is earthed through a metal object.
This could cause a shock or nasty burn.

Do not reverse the battery connections.

Components such as the alternator,
electronic control units, or any other
components having semi-conductor circuitry
could be irreparably damaged.

If the engine is being started using jump

leads and a slave battery, connect the
batteries positive-to-positive and negative-
to-negative (see “Roadside Repairs - jump
starting”). This also applies when connecting
a battery charger.

Never disconnect the battery terminals,

the alternator, any electrical wiring or any
test instruments when the engine is running.