1998 JAGUAR X308 check engine

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.

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

Bracket on top of gearbox or Bulkhead rear of engine
With EM021 disconnected, measure the voltage between
EM021/003 and EM021/004. 3
Is the voltage between 600mV and 1.0 Volt?
Yes
GO to A4
No Renew O2 sensor; reconnect plug(s)
GO to A6
A4: CHECK FOR O2 SENSOR FAILURE
With the conditions held as A3, suddenly decelerate to idle. 1
Has the voltage dropped to 400mV or less ?
Yes GO to A5
No Renew O2 sensor; reconnect plug(s)
GO to A6
A5: CHECK FOR O2 SENSOR FAILURE
With the conditions held as A4, suddenly accelerate to
approximately 2500 rpm. 1
Has the voltage risen to between 600mV and 1 volt?
Yes GO to A7
No Renew O2 sensor; reconnect plug(s)
GO to A6
A6: 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
A7: HEATED O2 SENSOR SHORT CIRCUIT TO GROUND

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

Connect the scan tool 1
Have the DTC(s) and freeze frame data been recorded?
Yes GO to C2
C2: CHECK FOR O2 SENSOR FAILURE
Ignition switch to position II 1
Disconnect EM022
Bracket on top of gearbox or Bulkhead rear of engine
2
Run the engine for a period to warm the sensor and then
maintain a steady speed of approximately 2500 rpm. 3
Measure the voltage between EM022/001 and EM022/002. 4
Is the voltage between 600mV and 1.0 Volt?
Yes
GO to C3
No Renew O2 sensor and reconnect plug(s).
GO to C6
C3: CHECK FOR O2 SENSOR FAILURE
With the conditions held as C2, suddenly decelerate to idle. 1
Has the voltage dropped to 400mV or less ?
Yes