1998 JAGUAR X308 ESP

The E
VAP canister purge valve controls th
e flow rate of fuel vapour drawn into the engine during the canister purge
operation. The valve is opened by a vacu um feed from the induction elbow : the vacu um feed is controlled by the integral
valve solenoid and is applied when the so lenoid is energised. The solenoid is pulsed on (energised) and off by a fixed
frequency (100Hz) variable pulse width control signal (pulse width modulation). By varying the pulse on to off time, the
ECM controls the duty cycle of the valve (time that the valve is open to time closed) and thus the vapour flow rate to the
engine.
With no ECM signal applied to the va lve solenoid, the valve remains closed.
Can
ister Purge Operation
The
following pre-conditions are ne
cessary for purging to commence :
aft
er battery disconnection/reconnection, engine
management adaptations must be re-instated.
engine has run for
at least 8 seconds.
engi

ne coolant temperature is not less than 70 °C.
engine

not running in the fuel
cut off condition (eg overrun).
t
he adaptive fuel correction
function has not registered a rich or lean failure
t
he evaporative emission leak test has not failed
no faults have been diagnosted in th
e rel
evant sensor and valve circuits -
Air Flow Meter (AFM), Engine Coolant
Temperature sensor, Evaporativ e Canister Purge valve and Canister Close Valve (CCV).
If these conditions have been satisfied, purging is started. If any failures are registered, purging is inhibited.
The canister(s) is purged during each driv e cycle at various rates in accordance with the prevailing engine conditions. The
engine management software st ores a map of engine speed (RPM) against engine load (grams of air inducted / rev). For
any given engine speed and load, a vapour purge rate is assigned (purge rate increases with engine speed and load).
The preset purge rates are base d on the assumption of a vapour concentratio n of 100%. The actual amount of vapour is
measured by the closed loop fueling system : the input of evaporative fuel into the engine causes the outputs from the
upstream oxygen sensors to change, the am ount of change providing a measure of the vapour concentration. This feedback
causes the original purge rate to be adju sted and also reduces the amount of fuel input via the injectors to maintain the
correct air to fuel ratio.
Engine speed/load mapping and the corresp onding purge rates are different for single canister, running loss and ORVR
evaporative systems.

Th
e engine management system provides optimum control of
the engine under all operating conditions using several
strategically placed sensors and any necessary actuators. Electronic engine control consists of:
engine
control module
throttle posi

tion sensor
engi

ne coolant temperature sensor
cam

shaft position sensor
c

rankshaft position sensor
mass air

flow sensor
intake air temper

ature sensor
kn

ock sensor
heat

ed oxygen sensor
Electronic Engine Control
Engine

Control Module (ECM)

The ECM incorporates a comprehensive monitoring and diagnostic capability including software variations to ensure system
compliance with the latest diagnostic and emissions legislation in different markets. The engine control module controls the
coil on plug ignition system, electronic fuel system, cr uise control and the electronic throttle control system.
The ECM responds to input signals received from sensors relating to engine operatin g conditions and provides output signals
to the appropriate actuators. These outp ut signals are based on the evaluated input signals which are compared with
calibrated data tables or maps held within th e ECM before the output signal is generated.
The ECM needs the following inputs to calibrate the engine properly:
cam
shaft position
It
em
Par
t Number
De
scription
1—Knock

sensor
2—Engine

coolant temperature sensor
3—Cranksh

aft position sensor
4—D

ownstream oxygen sensor
5—Upstream oxygen sensor
6—Camshaft position

sensor
P
arts List
engi

ne rpm
engi

ne coolant temperature
amount

of engine detonation

generates a signal when th
e dr
ive plate passes the sensor
sen
ds the ECM signals indicating crankshaft position and engine speed
is e

ssential for calculating spark timing
En

gine Coolant Temperature (ECT) Sensor
sen
ds the ECM a signal indicating the temperature of the engine coolant
is a t

emperature dependent resistor with a negative temperature coefficient (resistance changes inversely with
respect to temperature) and is constantly monitored by the ECM
Intake Air Temperature (IAT) Sensor

is m
ounted in the same housing as the MA
F sensor but is not a serviceable item
sen
ds the ECM a signal indicating the temperature of the air entering the engine
is a t

emperature dependent resistor which has a negative
temperature coefficient (its resistance changes inversely
with respect to ambient temperature).
Knock S
ensor (KS)
is a pi
ezo-electric device which sends a signal
to the ECM indicating engine detonation
Between 700 and 6800 rpm, the ECM will retard individual cylinder ignition timing when detonation occurs while allowing
the other cylinders to continue operating normally.
During acceleration, at critical load and speed conditions, the ECM retards ignition timing to prevent the onset of detonation.
H
eated Oxygen Sensor (HO2S)
are
positioned upstream of the catalytic convertor
is equipped with

a heating element wh
ich improves the response time of the sensors during engine warm-up
h
as the ability to generate a voltage signal proportional to the oxygen content of the exhaust gases leaving the
engine
pr
ovides feedback information to the ECM used to calc
ulate fuel delivery and provide optimum gas emissions
Variable V
alve Timing (VVT) Solenoid
R
efer to section 303-01.

Driver Information
Chart
•

NOTE: Use this table to identify DTCs associated with the me
ssage center display, then refer to the DTC index for possible
sources and actions.
• NOTE: For definitions of Default Modes, see the foot of this table.
Poor
dr iveabilityEngine h e
sitates/poor
acceleration
Fue l
pump
Exhaus
t gas
recirculation
(EGR)
Air leakage Stop lamp swi t
ch
Throttl
e
sensors
Throttl
e
motor
Spark
plugs
fouled
Check f
o
r water ingress
into spark plug wells
Ignition coil fail
ure(s)
HT sh
o
rt to ground
(tracking) check rubber
boots for cracks/damage
ECM failu r
e
Check f
u
el pressure. For EGR information,
REFER to Section 303
-08 En gin
e Emission
Control.
F or i
ntake system information,
REFER to Section 303
-1 2
Intake Air Distribution

and F
ilt
ering
.
F or stop l
amp switch in
formation, refer to the
wiring diagrams. For throttle position sensor
tests,GO to Pinpoint Test D.
. Fo
r throttle motor
control circuit tests,GO to Pinpoint Test T.
. For
igni t
ion system,
REFER to Section 303
-07 En
gine Ignition
.
F or ECM
circuit tests,GO to Pinpoint Test
AD.
.
Engine backfiresFuel
pump
Air leakage MAF se

nsor
HO2 sensors
Spark plugs Check fo
r water ingress
into spark plug wells
HT sh o
rt to ground
(tracking) check rubber
boots for cracks/damage
Ignition coil fail
ure(s)
Chec
k fu
el pressure. For intake system
information,
REFER to Section 303
-12
Intake Air Distribution

and Filt
ering
.
F or MAF sensor ci
rcuit test
s,GO to Pinpoint Test
A.
. F or HO2 sensor
circui
t tests, check for DTC
indicating which sensor and follow indicated pinpoint test. For ignition system,
REFER to Section 303
-07 En
gine Ignition
.
Engine
s
urges
Air leakage
Fuel
pump
Stop lamp swit

ch
MAF s
e
nsor
Harness Throttl
e
sensors
Throttl
e
motor
Spark plugs
Check fo
r water ingress
into spark plug wells
HT sh o
rt to ground
(tracking) check rubber
boots for cracks/damage
ECM failu r
e
Fo
r
intake system,
REFER to Section 303
-1 2
Intake Air Distribution

and Filt
ering
.
Check fu
el pressure. For
stop lamp information,
refer to the wiring diagrams. For MAF sensor tests,GO to Pinpoint Test A.
. Fo
r throttle
position sensor tests,GO to Pinpoint Test D.
,
a n
dGO to Pinpoint Test
K.
. Fo
r throttle motor
circuit tests,GO to Pinpoint Test T.
. For ig
nition
system,
REFER to Section 303
-07 En
gine Ignition
.
F or ECM
circuit tests,GO to Pinpoint Test
AD.
.
Engine detonates/k
nocks
Fue
l
pump
HO2 sensors
Air leakage Blocked part-load breather
(s
ervice action S474)
Mass ai
r fl
ow (MAF) sensor
Chec
k fu
el pressure. Fo
r HO2 sensor circuit
tests, check for DTC indicating which sensor and
follow indicated pinpoint test. For intake system
information,
REFER to Section 303
-1 2
Intake Air Distribution

and Filt
ering
.
Check service action S474
. For MAF sensor
tests,GO to Pinpoint Test A.
.
No t
hrottle response
Traction contr
o
l invoked
Throttl
e
sensors
Throttl
e
motor
Fo
r th
rottle position sensor tests,GO to Pinpoint
Test D.
, andG O to Pinpoint
Test
K.
. Fo
r throttle

motor circuit tests,GO to Pinpoint Test T.
.
Cru i
se control inhibited or

disabled
Cru i
se control switch
Throttle

sensors
Stop lamp swit

ch
For cru
i
se control switches,
REFER to Section 310
-03
Speed Control
.
For th
rottle position sensor tests,GO to Pinpoint
Test D.
, andG O to Pinpoint
Test
K.
. For s t
op
light switch information, refer to the wiring diagrams.

P0122Throttle
position (TP) sensor 1 low
voltage
TP se ns
or to ECM sensing circuit 1
(TP sensor pin 3) open circuit or
high resistance
TP sensor fail
ure
F
o
r TP sensor circ
uit tests,GO to
Pinpoint Test D.
, and GO
to Pinpoint
Test K.
.
P0123Throttl e
position (TP) sensor 1
high voltage
TP se ns
or to ECM sensing circuit 1
(TP sensor pin 3) short circuit to
high voltage
TP sensor fail
ure
F
o
r TP sensor circ
uit tests,GO to
Pinpoint Test D.
, and GO
to Pinpoint
Test K.
.
P0125En
gine coolant temperature (ECT)
sensor response (for closed loop
fuel control)
Low/contaminated coolant Therm o
stat failure
ECT se
ns
or to ECM sensing circuit
high resistance, open circuit or
short circuit to high voltage
Che c
k coolant level and condition.
Check thermostat function. For ECT
sensor circuit tests,GO to Pinpoint
Test C.
.
P0131Right -
hand H02S sense circuit low
voltage
H02 S
disconnected
H0
2S to
ECM wiring open circuit
H0
2S short ci
rcuit to ground
H0
2S fail
ure
F
or R
ight-hand HO2S circuit tests,GO
to Pinpoint Test E.
.
P0132Right-
hand H02S sense circuit
high voltage
H02 S
sensing circuit short circuit to
high voltage
H0 2S groun
d braided shield open
circuit
H0 2S fail
ure
F
or R
ight-hand HO2S circuit tests,GO
to Pinpoint Test E.
.
P0133Right-
hand H02S sense circuit
slow response
Engine m
isfire
H02
S
disconnected
H0
2S mechanical damage

H0
2S to
ECM wiring intermittent
open circuit
H02 S
sensing circuit short circuit to
high voltage
H02S short ci
rcuit to ground
H02S groun

d braided shield open
circuit
H0 2S heater circuit faul
t
Exhaus
t leak

Low e
x
haust temperature
Injector fl
ow parti
ally blocked
Catal
y
st efficiency decrease
H0
2S fail
ure
Chec
k for 'en
gine misfire detected'
DTCs. For HO2S circuit tests,GO to
Pinpoint Test E.
.G
O to Pinpoint Test
F.
. Check for exhaust leaks,
REF
ER to Section 309
-00
Ex
haust
Sy
ste
m
.
Chec k inje
ctors,
REFER to Section 303
-04 Fu
el
Charging and Cont

rols
.
P0135Right
-
hand H02S heater circuit
malfunction
H02 S
disconnected
H0
2S h
eater power supply open
circuit
H0 2S heater to ECM wi
ring short
circuit or open circuit
H0 2S heater fai
lure
F
o
r right-hand HO2S heater circuit
tests,GO to Pinpoint Test F.
.
P0137Right-
hand catalyst monitor
sensor sense circuit low voltage
Catal y
st monitor sensor
disconnected
Catal y
st monitor sensor to ECM
wiring open circuit
Catal y
st monitor sensor short
circuit to ground
Cat a
lyst monitor sensor failure
F
or ri
ght-hand catalyst monitor sensor

circuit tests,GO to Pinpoint Test G.
.
P0138Right -
hand catalyst monitor
sensor sense circuit high voltage
Catal y
st monitor sensor sensing
circuit short circuit to high voltage
Catalyst
monitor sensor ground
braided shield open circuit
Cata
lyst monitor sensor failure
F
or ri
ght-hand catalyst monitor sensor

circuit tests,GO to Pinpoint Test G.
.
P0140Right -
hand catalyst monitor
sensor sense circuit no activity
Catal y
st monitor sensor
disconnected
Catal y
st monitor sensor
mechanical damage
Catal y
st monitor sensor to ECM
wiring open circuit
Catal y
st monitor sensor sensing
circuit short circuit to high voltage
Cataly
st monitor sensor short
circuit to ground
Catalyst
monitor sensor ground
braided shield open circuit
F or ri
ght-hand catalyst monitor sensor

circuit tests, GO to Pinpoint Test G.
.
Check f o
r exhaust leaks,
REFER to Section 309
-00 Ex
haust
Sy
ste
m
.
Chec k inje
ctors,
REFER to Section 303
-04 Fu
el
Charging and Con
t
rols
.

Exhaus
t leak
Low e

xhaust temperature
Cat

alyst monitor sensor failure
P0151Le

ft-hand H02S sense circuit low
voltage
H02
S disconnected
H0

2S to ECM wiring open circuit
H0

2S short circuit to ground
H0

2S failure
F
or left-hand HO2S circuit tests, GO
to Pinpoint Test H.
.
P0152Le
ft-hand H02S sense circuit high
voltage
H02
S sensing circuit short circuit to
high voltage
H0
2S ground braided shield open
circuit
H0
2S failure
F
or left-hand HO2S circuit tests,GO to
Pinpoint Test H.
.
P0153Le
ft-hand H02S sense circuit slow
response
Engine
misfire
H02

S disconnected
H0

2S mechanical damage
H0

2S to ECM wiring intermittent
open circuit
H02
S sensing circuit short circuit to
high voltage
H0
2S short circuit to ground
H0

2S ground braided shield open
circuit
H0
2S heater circuit fault
Exhaus

t leak
Low e

xhaust temperature
Injector fl

ow partially blocked
Catal

yst efficiency decrease
H0

2S failure
Chec
k for 'engine misfire detected'
DTCs. For HO2S circ uit tests, GO to
Pinpoint Test H.
. Check for exhaust
leak
s,
REFER to Section 309
-00
Exhaust
Sy

stem
.
Chec
k injectors,
REFER to Section 303
-04
Fuel
Charging and Con

trols
.
P0155Left-hand H02S heater

circuit
malfunction
H02
S disconnected
H0

2S heater power supply open
circuit
H0
2S heater to ECM wiring short
circuit or open circuit
H0
2S heater failure
F
or left-hand HO2S heater circuit
tests,GO to Pinpoint Test I.
.
P0157Le
ft-hand catalyst monitor sensor
sense circuit low voltage
Catal
yst monitor sensor
disconnected
Catal
yst monitor sensor to ECM
wiring open circuit
Catal
yst monitor sensor short
circuit to ground
Cat
alyst monitor sensor failure
F
or left-hand catalyst monitor sensor
circuit tests,GO to Pinpoint Test J.
.
P0158Le
ft-hand catalyst monitor sensor
sense circuit high voltage
Catal
yst monitor sensor sensing
circuit short circuit to high voltage
Catalyst
monitor sensor ground
braided shield open circuit
Cat
alyst monitor sensor failure
F
or left-hand catalyst monitor sensor
circuit tests,GO to Pinpoint Test J.
.
P0160Le
ft-hand catalyst monitor sensor
sense circuit no activity
Catal
yst monitor sensor
disconnected
Catal
yst monitor sensor
mechanical damage
Catal
yst monitor sensor to ECM
wiring open circuit
Catal
yst monitor sensor sensing
circuit short circuit to high voltage
Catal
yst monitor sensor short
circuit to ground
Catalyst
monitor sensor ground
braided shield open circuit
Exhaus
t leak
Low e

xhaust temperature
Cat

alyst monitor sensor failure
F
or left-hand catalyst monitor sensor
circuit tests,GO to Pinpoint Test J.
.
Check f
or exhaust leaks,
REFER to Section 309
-00
Exhaust
Sy

stem
.
P0171Right

-hand cylinders combustion
too lean
Air
intake leak between MAF senso
r and th

rottle
F

uel filter system blockage
F

uel injector blockage
F

uel pressure regulator failure (low

fuel pressure)
Low f
uel pump output
Check ai
r intake system for leaks,
REFER to Section 303
-1
2 Intake Air
Distribu

tion and Filtering
.
Check the fuel fi
lter,
REFER to Section 310
-01
Fuel Tank
and Lines.
Chec
k the fuel injectors and fuel

Di
sconnect the ECM electrical connector, EM11.
2
Disc
onne
ct the TP sensor electrical connector, PI06.
3
Meas
ure t
he resistance between EM11, pin 11 (U) and PI06, pin 03 (U).
4
Is th
e res
istance greater than 5 ohms?
Yes REPAIR the high resistance circui t. For additional information, refer to the wiring diagrams. CLEAR
the DTC. TEST the system for normal operation.
No GO to D2
.
D2
: CHECK THE TP SENSOR SENSE CIRCUIT FOR SHORT TO HIGH VOLTAGE
Re

connect the battery negative terminal.
1
Turn the ignition swit

ch to the ON
position.
2
Me
asure the voltage between PI06, pin 03 (U) and GROUND.
3
Is the volt

age greater than 5 volts?
Yes REPAIR the short circuit. For addi tional information, refer to the wiring diagrams. CLEAR the DTC.
TEST the system for normal operation.
No GO to D3
.
D3: CH
ECK THE TP SENSOR SENSE CIRCUIT FOR SHORT TO GROUND
Turn the ignition swi
t
ch to the OFF
position.
1
Measure t
he resistance between PI06, pin 03 (U) and GROUND.
2
Is
t
he resistance less than 10,000 ohms?
Yes REPAIR the short circuit. For addi tional information, refer to the wiring diagrams. CLEAR the DTC.
TEST the system for normal operation.
No INSTALL a new TP sensor.
REFER to Throttle Position (TP) Sensor
in this
section.
CLEAR the DTC. TEST the syst em for normal operation.
PI
NPOINT TEST E : DTC P0131, P0132, P0133; RIGHT-HAND H02S LOW/HIGH VOLTAGE, SLOW
RESPONSE
•
NOTE: Before commencing this test, check the sensor connect
ions and harness, check for exhaust leaks, engine misfire,
etc. See 'visual inspection ch art' and 'possible causes'.
TES
T
CONDITIONS
D E
TAILS/RESULTS/ACTIONS
E1
: CHECK THE H02S
SENSE CI
RCUIT FOR HIGH RESISTANCE
Disc
onnect the battery negative terminal.
1
D
is
connect the H02S electrical connector, EM21.
2
Disc
onne
ct the ECM electrical connector, EM12
3
Meas
ure t
he resistance between EM21, pin 03 (R) and EM12, pin 15 (R).
4
Is th
e res
istance greater than 5 ohms?
Yes REPAIR the high resistance circui t. For additional information, refer to the wiring diagrams. CLEAR
the DTC. TEST the system for normal operation.
No GO to E2
.
E2: CHECK THE H02S
SENSE CIRCUI
T FOR SHORT TO HIGH VOLTAGE
Re
connect the battery negative terminal.
1
Turn the ignition swi
t
ch to the ON
position.
2
Measure t
he voltage between EM12, pin 15 (R) and GROUND.
3
Is th
e volt
age greater than 3 volts?
Yes REPAIR the short circuit. For addi tional information, refer to the wiring diagrams. CLEAR the DTC.
TEST the system for normal operation.
No GO to E3
.
E3: CHECK THE H02S
SENSE CI
RCUIT FOR SHORT TO GROUND
Turn the ignition swi t
ch to the OFF
position.
1
Measure t
he resistance between EM12, pin 15 (R) and GROUND.
2

CLEAR th
e DTC. TEST the syst
em for normal operation.
PINPOINT TES
T G : DTC P0137, P0138; RIGH
T-HAND CATALYST MONITOR SENSOR LOW/HIGH
VOLTAGE, NO ACTIVITY
TE S
T
CONDITIONS
D E
TAILS/RESULTS/ACTIONS
G1
: C
HECK THE CATALYST MONITOR SENSOR SENSE CIRCUIT FOR HIGH RESISTANCE
Di
sc
onnect the battery negative terminal.
1
Di
sc
onnect the catalyst monitor sensor electrical connector, EM22.
2
Disc
onne
ct the ECM electrical connector, EM12.
3
Meas
ure t
he resistance between EM22, pin 02 (U) and EM12, pin 17 (U).
4
Is th
e res
istance greater than 5 ohms?
Yes REPAIR the high resistance circui t. For additional information, refer to the wiring diagrams. CLEAR
the DTC. TEST the system for normal operation.
No GO to G2
.
G2: CHECK
THE CATALYST MONITOR SENSOR SE
NSE CIRCUIT FOR SHORT TO HIGH VOLTAGE
Re
connect the battery negative terminal.
1
Turn the ignition swi
t
ch to the ON
position.
2
Measure t
he voltage between EM12, pin 17 (U) and GROUND.
3
Is th
e volt
age greater than 3 volts?
Yes REPAIR the short circuit. For addi tional information, refer to the wiring diagrams. CLEAR the DTC.
TEST the system for normal operation.
No
GO to G3
.
G3: CHECK
THE CATALYST MONITOR SENSOR
SENSE CIRCUIT FOR SHORT TO GROUND
Turn the ignition swit
ch to the OFF
position.
1
Measure t
he resistance between EM12, pin 17 (U) and GROUND.
2
Is t

he resistance less than 10,000 ohms?
Yes REPAIR the short circuit. For addi tional information, refer to the wiring diagrams. CLEAR the DTC.
TEST the system for normal operation.
No GO to G4
.
G4: CHECK
THE CATALYST MONITOR SENSOR
GROUND CIRCUIT FOR OPEN CIRCUIT
Reconn
ect the ECM electrical connector, EM12.
1
Meas
ure t
he resistance between EM22, pin 01 (BRD) and GROUND.
2
Is th
e res
istance greater than 5 ohms?
Yes REPAIR the circuit (this is a braide d lead which would require different repair techniques to standard
wiring). For additional information, refer to the wiring diagrams. CL EAR the DTC. TEST the system for
normal operation.
No INSTALL a new catalyst monitor sensor.
REFER to Catalyst Monitor Sensor RH
in this
section.
CLEAR the DTC. TEST the syst em for normal operation.
PINPOINT TES
T H : DTC P0151, P0152, P0153;
LEFT-HAND H02S LOW/HIGH VOLTAGE, SLOW
RESPONSE
•
NOTE: Before commencing this test, check the sensor connect
ions and harness, check for exhaust leaks, engine misfire,
etc. See 'visual inspection ch art' and 'possible causes'.
TES
T
CONDITIONS
D E
TAILS/RESULTS/ACTIONS
H1:
C
HECK THE H02S SENSE CIRCUIT FOR HIGH RESISTANCE
Di
sc
onnect the battery negative terminal.
1
D
is
connect the H02S electrical connector, EM23.
2
Disc
onne
ct the ECM electrical connector, EM12.
3
Meas
ure t
he resistance between EM23, pin 03 (G) and EM12, pin 14 (G).
4
Is th
e res
istance greater than 5 ohms?