StephenPope

My CEL has been illuminating recently - codes 22 (Knock Sensor) & 23 MAF Sensor.)
Was showing a would be buyer the car (it's for sale) and connected the black spade (to do the self diagnostic test) connectors to demonstrate the problem to the guy.
When I disconnected the black spade connectors, I disconneced the wrong ones but did not realise at the time! - Doh! The CEL then stayed on whilst we drove aroud a bit until I checked and realised what I had done! I disconnected the correct wires this time and re-connected the other multi- plug. Unfortunately the CEL stayed illuminated and on WOT, the car appeared to misfire slightly.
I did another self diagnosis and another code 12 (start switch) came up. I therefore assume that the multi -plug I connected by a mistake must have caused this problem.
2 Questions:
1.When the CEL is illumnated, does the ECU 'tell' the car not to fuel properly to 'protect' the engine until the CEL goes out?
2.Does adding a new problem to the brain, cause the CEL to stay illuminated?
Fortunately, the guy still wants to buy the car and we agreed a price (commented that the car was a nice clean car!!) however I asked him if I could investigate/ repair further. The car is getting dropped off at S&S tonight for the repair ASAP.
An urgent answer to the above would be appreciated. New car will hopefuly be a Pro-drive Bug eye STI - woo hoo!!!
Woops - meant a blob eye1!!