#29 ECU Memory Check... If this fault is detected, all other faults are unreliable and must be ignored. 
Proceed as follows:
1) Leave battery connected
2) Switch OFF Ignition.
3) Wait approx. 5-seconds.
4) Disconnect ECU plug.
5) Re-Connect ECU plug.
6) Switch Ign ON and check display unit.
If #29 is detected again, substitute ECU & re-test.

#44 Lamda Sensor A, Left Hand.
#45 Lamda Sensor B, Right Hand.
If both codes displayed, check voltage to heater coils.

#25 Ignition Misfire... Followed by Right or Left codes...
#40 Indicates misfire on Left Bank
#50 Indicates misfire on Right Bank
If #40/#50 displayed, check:
1) Dist Cap.
2) Rotor Arm.
3) Coil.
4) Elec Connections.
5) Pick-up (airgap @ dist).
6) Amplifer.
7) Injectors (if code #34 or #36 are displayed).
If ONLY #40 or #50 are displayed, check... per bank:
1) Spark Plug on that bank.
2) Plug Wires on that bank.
3) Dist Cap.
4) Injectors for that bank.

#12 Airflow Meter.

#21 Fuel Tune Select... Open circuit.

#34 Injector Bank-A... Left, Causing engine to run rich or lean.
#36 Injector Bank-B... Right, Causing engine to run rich or lean.

#14 Coolant Thermistor.

#17 Throttle Potentiometer.

#18 Throttle Potentiometer... Input high -- Airflow Meter low.
#19 Throttle Potentiometer... input low -- Airflow Meter high.

#88 Purge Valve Leak.

#28 Air Leak... Check for Air leaks in the following areas:
1) Hose, air flow meter to plenum.
2) Breather system hoses to plenum.
3) Vacuum reservoir hose.
4) Dist Vacuum hose.
5) Hose, purge valve to plenum.
6) Injector seals.
7) Gaskets, inlet manifold, check all.
8) By-pass air valve hose.

#23 Fuel Supply... Check system pressure.

#48 Stepper Motor... Check Base Idle speed and/or speed sensor.

#68 Road Speed Sensor... Check sensor.

#69 Gearswitch.

#59 Group Faults 23/28... Indicates fault has been registered that is caused by fuel supply or air leak,
Exact fault cannot be identified. Check items from #23 & #28.

#15 Fuel Thermistor.

To Clear Faults...
1) Switch Ignition ON -- Do Not Start Engine.
2) Disconnect Serial Link plug, wait 5+ seconds.
3) Re-connect Serial Link plug.
4) Switch OFF Ignition, wait for main relay to drop out (click).
5) Switch Ignition ON and check display unit for further codes to appear. Clear each as above.


This System fitted from Chassis Pre-fix "LA" onwards.


This information has been taken, in part, from Range Rover NAS (RRNA) Service Manual.