Had previous post on here as to traction light and check engine light coming on, well after various workshops and local Holden dealer all had different opinions and I swapped parts with my engine in my car and replaced things like o2 sensors air& fuel filters set of leads, 2 broken exhuast bolts checking inlet and hoses for vacuem leaks & having injecters cleaned 2 of which were showing a bit different spray pattern and checking battery and charge rate still could not chase fault down. Then having no luck at Dealer I got Holden Customer department involved thru Melbourne they got there tech guys involved and hey presto local dealer we think has solved it ,It seems oil presure switch was pumping oil up wiring to computer and shorting out Of course they want to replace engine loom but at this stage have replaced switch and I am cleaning up oil in switch connecter with electrical solvent hopefully this will fix this problem Thanks to Dr terry for his help along the way