1998 JAGUAR X308 sensor

With EM012 and EM021 disconnected, measure the
resistance between EM012/015 and EM021/003 1
Is the resistance < 0.5 OHM?
Yes GO to A13
No Inspect harness / connecto rs EM012, and EM021 for
corrosion, damaged / pushed back pins. Repair as required
and reconnect plug(s).
GO to A18
A13: HEATED O2 SENSOR SCREEN GROUND CONTINUITY

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

Ignition switch to position 0 1
Remove EMS fuse F14 2
Disconnect EM010 and EM015
Inside ECM housing
3
Using a link lead, bridge EM010/016 and EM010/022 4
Ignition switch to position II 5
Measure the voltage between EM010/023 and EM015/002 6
Is the voltage 0 (zero) V?
Yes Replace EMS fuse F14 but retain link lead
GO to A17
No Inspect harness / connectors EM010, EM015, and EM021 for
corrosion, damaged / pushed back pins. Repair as necessary
and reconnect plug(s).
GO to A18
A17: CHECK B+ AT O2 SENSOR HEATER CIRCUIT

Connect the scan tool 1
Have the DTC(s) and freeze frame data been recorded?
Yes GO to B2
B2: CHECK FOR LOW EX HAUST TEMPERATURE
Check the engine and exhaust system for normal running
temperature 1
Is the engine and exhaust sy stem up to normal running
temperature?
Yes GO to B3
No Rectify possible leaking exhaust manifold / catalyst, general
causes of an over rich mixture and engine cooling system
operation. Test the system for correct operation.
GO to B8
B3: CHECK FOR O2 SENS OR 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 B4
No Renew O2 sensor, reconnect plug(s).
GO to B8
B4: 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
Measure the voltage between EM021/003 and EM021/004. 2
Is the voltage between 600mV and 1.0 Volt?
Yes
GO to B5
No Renew O2 sensor, reconnect plug(s).
GO to B8
B5: CHECK FOR O2 SENSOR FAILURE
With the conditions held as B4, suddenly decelerate to idle. 1
Has the voltage dropped to 400mV or less ?
Yes GO to B6
No Renew O2 sensor, reconnect plug(s).
GO to B8
B6: CHECK FOR O2 SENSOR FAILURE
With the conditions held as B5, suddenly accelerate to
approximately 2500 rpm. 1
Has the voltage risen to between 600mV and 1 volt?
Yes

GO to B7
No Renew O2 sensor, reconnect plug(s).
GO to B8
B7: CHECK FOR O2 SENSOR FAILURE
With the conditions held as in B6, run the engine at 1500
rpm for approximately 2 minutes. 1
Does the displayed voltage drop below 400mV and rise above 500 mV, cycling approximately every 4 seconds?
Yes GO to B9
No Renew O2 sensor, reconnect plug(s).
GO to B8
B8: STOP
Perform appropriate service drive cycle and check for the
presence of DTC. 1
Has the fault code cleared?
Yes STOP
No Contact Jaguar Service
B9: HEATED O2 SENSOR SHORT CIRCUIT TO GROUND

With EM021 disconnected measure the insulation resistance
between sensor pin 001 and sensor body. 1
Repeat for pin 003 and sensor body. 2
Is the resistance > 10 MOHM?
Yes GO to B11
No Renew the O2 sensor and reconnect plug(s).
GO to B10
B10: STOP
Perform appropriate service drive cycle and check for the
presence of DTC. 1
Has the fault code cleared?
Yes STOP
No Contact Jaguar Service
B11: SIGNAL GROUND 1 CONTINUITY

With EM010 and EM014 disconnected, measure the
resistance between EM014/004 and chassis ground EM008L. 1
Is the resistance < 0.5 OHM?
Yes GO to B14
No Inspect connector EM014 for co rrosion, damage, or pushed
back pins.
Inspect earthing stud EM008L for corrosion.
Inspect harness, splice EMS36.
Repair as required an d reconnect plug(s).
GO to B13
B13: CHECK FOR HEATED O2 SENSOR CONTINUITY