Consciousness in Nibbana In the Abhidhamma, it makes mention to 89 and 121 states of consciousness. It says there are four ultimate realities namely


Consciousness
Mental Factors 
Matter 
Nibbana.
The first three are conditioned, nirvana is unconditioned. 


According the Abhidhamma, It states that persons who've attained nirvana no longer have consciousness. What does this mean exactly? 

In the Mundane, sense-sphere, rootless consciousness, it says that “body consciousness, accompanied by pain” is the result of unwholesome karma. Does this mean that enlightened beings such as a Buddha or an arahant don't feel pain when they touch something hot?
There are two types of nirvana: saupādisesa-nibbāna (nirvana with remainder) and anupādisesa-nibbāna (nirvana without remainder) (Iti. 44). 

It is true that for one who has attained anupādisesa-nibbāna there will be no more consciousness. This is because someone who has attained anupādisesa-nibbāna is dead*. It is the equivalent to the more familiar parinibbāna - "complete" nirvāna. For one who has attained saupādisesa-nibbāna, there is still the physical and mental formations that have been created as a result of being born as a human that need to work themselves out, including consciousness.

* Conventionally speaking; technically, they have become free from death, since they have become free from birth (arising).