Just thought I'd share with you some very handy info I was given tonight (by a Nissan tech).

Its easy to check the ecu fault codes - something I didn't realise.
I believe the below would also be in the manual...
(btw MIL = Malfunction Indicator Lamp - otherwise known as CEL / Check Engine Light - its orange and on the right hand side of the dash in the M35).

ACCESSING:

NOTE: To access trouble codes, accelerator pedal position (APP) sensor must be functioning correctly.

• Ensure accelerator pedal is fully released
• Switch ignition ON. DO NOT start engine
• Wait 3 seconds
• Within 5 seconds, repeat the following 5 times:
• > Fully depress accelerator pedal.
• > Fully release accelerator pedal.
• Wait 7 seconds.
• Fully depress accelerator pedal and hold.
• After approximately 10 seconds MIL will start flashing.
• Fully release accelerator pedal.
• Trouble codes are now displayed by MIL.
• Count MIL flashes.
• Compare to trouble code table.
• Each trouble code consists of four groups of one or more flashes.
• Ten flashes in a group indicate '0'.
• The first group of flashes indicate the 'thousands' of the trouble code.
• The second group of flashes indicate the 'hundreds' of the trouble code.
• The third group of flashes indicate the 'tens' of the trouble code.
• The fourth group of flashes indicate the 'units' of the trouble code.
• A short pause separates each trouble code group.
• A long pause separates each trouble code.
• Switch ignition OFF.

ERASING:

• Ensure accelerator pedal is fully released.
• Ensure ignition switched OFF for at least 10 seconds.
• Switch ignition ON - DO NOT start engine.
• Wait 3 seconds.
• Within 5 seconds, repeat the following 5 times:
• > Fully depress accelerator pedal.
• > Fully release accelerator pedal.
• Wait 7 seconds.
• Fully depress accelerator pedal and hold.
• After approximately 10 seconds MIL will start flashing.
• Fully release accelerator pedal.
• Trouble codes are now displayed by MIL.
• Fully depress accelerator pedal for more than 10 seconds.
• Fully release accelerator pedal.
• Trouble code 0000 should be displayed.

Mine showed the code 0000 (10 flashes x 4 times) so didn't solve the problem I was looking for but at least I know all the sensors are working etc.