According to the Lecture notes at IIT (Rupa chapter 17),
Only the mental factor known as cetanā has the capacity to bring forth results (vipaka), as long as latent ignorance, craving and conceit are not eradicated.Therefore centanā associated with path consciousness do not produce results.
Kamma, Kammajarūpa, Kammajakalāpa and Kammajasantati
Kamma
2.70.Kamma represents the wholesome or unwholesome cetanā. These good and bad volitions other than performing physical, verbal and mental acts has the capacity to produce resultant mentalities and matter in the future. Resultant mentalities are called vipāka-cittacetasika while resultant matter is called kammajarūpa. The ability of kamma to produce results has been expressed in Paṭṭhāna as follows.
Kusalākusalaṃ kammaṃ vipākānaṃ khandhānaṃ kaṭattā ca rūpānaṃ kammapaccayena paccayo.[1]
2.71. Mūlaṭīkā offers us the requirement for a mentality to be of the capacity to yield results –
“Vipaccanasabhāvatā ca anupacchinnāvijjātaṇhāmānasantāne sabyāpāratā” – “Capacity to
yield results is owing to the nature of being effortful in a mind stream where ignorance, craving and community are not eradicated”.[2] Though the statement is referring to the capacity of mentalities to produce resultant mentalities, vipākacittacetasikas, the same attribute is necessary to produce kamma-born matter as well.The above definition can be further elaborated in the following manner. Here, effortfulness refers to being a consciousness that is not produced by a past kamma. It means a vipāka mentality cannot produce new results. Furthermore, only powerful mentalities that are called javana (dynamic mentalities) has the capacity to produce results in future. Two adverting consciousness, even though being effortful cannot produce results. Finally, only a mentality that is being affected by latent avijjā, taṇhā, and māna garners the nature of producing results. According to it, mentalities of an arahant would not produce vipāka and kammajarūpa.
Finally, according to Paṭṭhāna, only the mental factor known as cetanā has the capacity to bring forth results.
Based on all this information the following fundamental can be formulated.
An effortful cetanā that arises together in javanacittas in a mind stream where latent ignorance, craving and conceit are not eradicated has the capacity to yield results in the future.
2.72. Though resultant mentalities and matter are produced by kammacetanā its associates such as
wisdom, faith, craving, anger do affect the nature of the prior.2.73. A kamma cannot produce kammajarūpas in the very life it has been done.[3]
2.74. According to Abhidhammatthasaṅgaha, only 25 kammacetanas have the capacity to produce kammajarūpas, even though there are altogether 33 kammacetanās. The 25 are: 12 cetanās associated with 12 akusalacittas, 8 cetanās associated with 8 mahākusalacittas and 5 cetanās associated with 5 rūpāvacarakusalacittas.
According to some scholars, the number is 24 excluding the cetanā associated with the
uddhaccasampayuttacitta.2.75. Out of the 33 kammacetanās, 4 arūpāvacarakusalacetanās and 4 lokuttarakusalacetanas (maggacetanās) do not produce kammajarūpas.
Arūpāvacarakusala is attained by developing matter-dispassion meditation (rūpavirāgabhāvanā). Therefore, arūpāvacarakusalacetanas that arise as the culmination of rūpavirāgabhāvanā do not produce kammajarūpas.
Maggacittas are attained by developing insight meditation which is also called mind-matterdispassion meditation. Therefore, centanā associated with path consciousness do not produce results that extend the generation of nāma and rūpa. The generation of nāma and rūpa is said to be extended when it is not let to extinguish at the death of a certain life. The extension happens when the dying being is reborn in a new life. Paṭisandhi vipāka citta cetasikas and kammajarūpas are vital in this extension. Therefore, maggacetanas do not produce kamma-born matter. Supra mundane path mentalities are of opposing nature to the continuation of saṃsāra.
[1] Pṭṭh. I. 7.
[2] Ml-ṭ. I. 38.
[3] On the other hand, a kamma can produce vipākacittacetasikas in the same life it has been executed.
So the Phala is not a Kamma-vipaka of Magga.