There is a fault with certain Jazz with an electronic throttle body where the wiring feeding it is rather tight within it's protective conduit. The tension on the wire at a 90° bend/join causes it to fail in an erratic manner.
The cables from the throttle body feed forward and down in conduit to a point where they join a larger conduit - it's at this point that the fault occurs, from memory people have mentioned 'the yellow/green wire' but I'll see if i can find the original posts.
- edit -Yes 'Yellow/green' wire,
"The fault was caused by a broken wire where the throttle body wiring meets the main wiring loom." Loss of power and engine management light on.
Fault codes P0638, P0121, P0122, P0221, P0222, P0607 all relating to throttle position and control module.
Also
http://www.honestjohn.co.uk/forum/post/index.htm?t=103253 mentions codes 40-16, 07-1, 07-5 and was fixed by mending a broken wire in the harness.
As you suspect, checking the wires at the junction of the two conduits is first task. New throttle body is expensive and attention probably not required.
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TG