1998 JAGUAR X308 heater

1
Turn the ignition swit
ch to the
ON position.
2
Meas ure t
he voltage between EM23, pin 01 (PS) 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 I4
.
I4
: CHECK H02S HEATER CONTROL CIRCUIT FROM ECM FOR SHORT TO GROUND
Turn the ignition swit

ch to the
OFF position.
1
Measure t
he resistance between EM23, pin 01 (PS) 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 H02S.
REFER to Heated Oxygen Sensor (HO2S) LH
in this
section.
CLEAR the DTC. TEST the system for normal operation.
P INPOINT TES
T J : DTC P0157, P0158; LEFT-H
AND CATALYST MONITOR SENSOR LOW/HIGH
VOLTAGE, NO ACTIVITY
TE S
T
CONDITIONS
D E
TAILS/RESULTS/ACTIONS
J
1
: CHECK THE CATALYST MONITOR SENSOR
SENSE CIRCUIT FOR HIGH RESISTANCE
Disc
onnect the battery negative terminal.
1
Di
sc
onnect the catalyst monitor sensor electrical connector, EM24.
2
Disc
onne
ct the ECM electrical connector, EM12.
3
Meas
ure t
he resistance between EM24, pin 02 (N) and EM12, pin 16 (N).
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 J2
.
J2
: CHECK THE CATALYST MONITOR SENSOR SENSE CIRCUIT FOR SHORT TO HIGH VOLTAGE
R
e
connect the battery negative terminal.
1
Turn the ignition swi
t
ch to the ON
position.
2
Measure t
he voltage between EM12, pin 16 (N) 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 J3
.
J3
: 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 16 (N) 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 J4
.
J4
: CHECK THE CATALYST MONITOR SENSOR
GROUND CIRCUIT FOR OPEN CIRCUIT
Reconn
ect the ECM electrical connector, EM12.
1
Meas
ure t
he resistance between EM24, 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

The upstream heated oxygen sensor is located at the catalytic converter inlet and detects the concentration of oxygen in the
raw exhaust gases; an internal heater reduces the warm up time of the sensor output.
An oxygen sensor (without heater) is located at the converter outlet.
The ECM receives input signals from the se nsors and varies the fuel injector duration (mixture) to provide optimum gas
emissions.
Circuit Diagram, O2 Sensors / ECM

Inspection and Verification
Vehicle Harness Check
1.1. Check for open and short circuit in harness conn ector faults between the O2 sensor and ECM.
2. 2. Check for approximately 12V between heater harness.
ItemDescription
1ECM
2Downstream oxygen sensor (A)
3Upstream heated oxygen sensor (A)
4Downstream oxygen sensor (B)
5Upstream heated oxygen sensor (B)
6Engine management fuse box

Heater Resistance Check
1.1. Verify that the resistance between the heater term inals is between 4OHM and 10OHM at -20°C to 100°C.
Performance Check
1.1. Run the engine at 2500 RPM for two minutes, to heat up the O2 sensor.
2. 2. Check the voltage of the sensor output: Alternates between less than 0.4V at feed back engine conditions and in
excess of 0.5V, see graph.

These voltages are for reference only.
3. 3. Check that cycle of the upstream se nsor output is in accordance with the appropriate pinpoint test.
4. 4. Check that cycle of the downstream sensor output is in accordance with the appropriate pinpoint test.

Exhaust System - Exhaust System
Diagnosis and Testing
Symptom Chart
Symptom Chart
Special Tool(s)

Digital multimeter

Generic scantool
SymptomPossible SourcesAction
DTC P0420 Catalyst system efficiency below
threshold (Bank 1)Catalyst failure
Upstream O2 sensor failure
Downstream O2 sensor failure
O2 sensor heater failure
Associated harness / connector failure
*
*
*
*
*See DTC P0137, P0138
and P0140
*
DTC P0430 Catalyst system efficiency below
threshold (Bank 2)Catalyst failure
Upstream O2 sensor failure
Downstream O2 sensor failure
O2 sensor heater failure
Associated harness / connector failure
*
*
*
*
*See DTC P0157, P0158
and P0160
*
DTC P0131 O2 sensor circuit low voltage (Bank 1
sensor 1)O2 sensor failure
Sensor ground fault
Harness failure
Connector pin(s) bent, loose or corroded
*
*
*
*GO to Pinpoint Test A
*
DTC P0132 O2 sensor circuit high voltage (Bank
1 sensor 1)O2 sensor failure to B+
Sensor ground fault
Harness failure
Connector pin(s) bent or tracking
between connections. O2 sensor failure
*
*
*
*
*GO to Pinpoint Test A
*
DTC P0133 O2 sensor circuit slow response
(Bank 1 sensor 1)O2 sensor heater failure / out of spec
Sensor ground fault
Harness failure
Connector pin(s) bent or tracking
between connections. Low exhaust temperature
O2 sensor failure
*
*
*
*
*
*GO to Pinpoint Test B
*
DTC P0135 O2 sensor heater circuit malfunction
(Bank 1 sensor 1)O2 sensor failure
Harness failure
Connector pin(s) bent or tracking
between connections. ECM failure
*
*
*
*GO to Pinpoint Test A
*
DTC P0137 O2 sensor circuit low voltage (Bank 1
sensor 2)O2 sensor failure
Sensor ground fault
Harness failure
Connector pin(s) bent, loose or corroded
*
*
*
*GO to Pinpoint Test C
*
DTC P0138 O2 sensor circuit high voltage (Bank
1 sensor 2)O2 sensor failure to B+
Sensor ground fault
Harness failure
Connector pin(s) bent or tracking
*
*
*
*GO to Pinpoint Test C
*

Pinpoint test A: P0131, P0132, P0135
between connections. ECM failure
*
DTC P0140 O2 sensor circuit no activity detected
(Bank 1 sensor 2)O2 sensor failure / out of spec
Sensor ground fault
Harness failure
Connector pin(s) bent or tracking
between connections. Low exhaust temperature
*
*
*
*
*GO to Pinpoint Test D
*
DTC P0420 Catalyst system efficiency below
threshold (bank 1)Downstream O2 sensor failure
Catalyst failure
Catalyst low temperature caused by
water splash
*
*
*GO to Pinpoint Test C
GO to Pinpoint Test D
*
*
DTC P0151 O2 sensor circuit low voltage (Bank 2
sensor 1)O2 sensor failure
Sensor ground fault
Harness failure
Connector pin(s) bent, loose or corroded
*
*
*
*GO to Pinpoint Test E
*
DTC P0152 O2 sensor circuit high voltage (Bank
2 sensor 1)O2 sensor failure to B+
Sensor ground fault
Harness failure
Connector pin(s) bent or tracking
between connections. O2 sensor failure
*
*
*
*
*GO to Pinpoint Test E
*
DTC P0153 O2 sensor circuit slow response
(Bank 2 sensor 1)O2 sensor heater failure / out of spec
Sensor ground fault
Harness failure
Connector pin(s) bent or tracking
between connections. Low exhaust temperature
O2 sensor failure
*
*
*
*
*
*GO to Pinpoint Test F
*
DTC P0155 O2 sensor heater circuit malfunction
(Bank 2 sensor 1)O2 sensor failure
Harness failure
Connector pin(s) bent or tracking
between connections. ECM failure
*
*
*
*GO to Pinpoint Test E
*
DTC P0157 O2 sensor circuit low voltage (Bank 2
sensor 2)O2 sensor failure
Sensor ground fault
Harness failure
Connector pin(s) bent, loose or corroded
*
*
*
*GO to Pinpoint Test G
*
DTC P0158 O2 sensor circuit high voltage (Bank
2 sensor 2)O2 sensor failure to B+
Sensor ground fault
Harness failure
Connector pin(s) bent or tracking
between connections. ECM failure
*
*
*
*
*GO to Pinpoint Test G
*
DTC P0160 O2 sensor circuit no activity detected
(Bank 2 sensor 2)O2 sensor failure / out of spec
Sensor ground fault
Harness failure
Connector pin(s) bent or tracking
between connections. Low exhaust temperature
*
*
*
*
*GO to Pinpoint Test H
*
DTC P0430 Catalyst system efficiency below
threshold (bank 2)Downstream O2 sensor failure
Catalyst failure
Catalyst low temperature caused by
water splash
*
*
*GO to Pinpoint Test G
GO to Pinpoint Test H
*
*
PINPOINT TEST A : P0131, P0132, P0135
TEST CONDITIONSDETAILS/RESULTS/ACTIONS
A1: RETRIEVE DTCS
• NOTE: Battery and or ECM disconnection prior to scanning wi
ll erase all data, ensure that the correct DTC is present.

Connect the scan tool 1
Have the DTC(s) and freeze frame data been recorded?
Yes GO to A2
A2: CHECK O2 SENSOR HEATER CONTINUITY
Ignition switch to position 0 1
Disconnect EM021
Bracket on top of gearbox or Bulkhead rear of engine
2
With EM021 disconnected, measure the resistance between
EM021/001 and EM021/002. 3
Is the resistance between 4 and 10 OHM?
Yes
GO to A3
No Renew O2 sensor; reconnect plug(s)
GO to A6
A3: CHECK FOR O2 SENSOR FAILURE
Run the engine for a period to warm the sensor and then
maintain a steady speed of approximately 2500 rpm. 1
Disconnect EM021 2

Is the voltage 0 (zero) V?
Yes GO to A16
No Inspect harness / connectors EM010, EM012, and EM021 for
corrosion, damaged / pushed back pins. Repair as necessary
and reconnect plug(s).
GO to A18
A16: CHECK FOR SHORT TO B+ AT O2 SENSOR HEATER