what does catalytic deficiency mean on a car would it cause my car to start bad?

Answer 1

When your car generates the "Catalytic Efficiency" code, the computer has run a series of tests to determine if your car complies with emissions level reduction strategies.
Your car has oxygen sensors at the engine to control fuel rate. It also has an oxygen sensor behind the catalytic converter.
The computer is constantly comparing the two signals.When the computer determines that it does not see a difference in the signals, it sets a code to tell the technician to test the system. It will also turn on the "Check Engine Light".

Answer 2

Might mean the converter is clogged or plugged. Using improper fuel and or having the engine operate out of the normal parameters can screw them up and if they are not flowing the gasses properly they cause back pressure making the engine run poorly and use more fuel