As was shown in arXiv:2609.14497, the 2-loop correction to the partition function of M2 brane wrapping AdS2ˆS[1] inside AdS4ˆS[7]{Zk vanishes. This is in agreement with the localization prediction for 1/2-BPS circular Wilson loop in ABJM theory interpreted in the grand-canonical ensemble according to the conjecture of arXiv:2505.21633. Here we study the 2-loop correction in the case of the M2 brane instanton wrapping S[3]{Zk Ă S[7]{Zk dual to the leading non-perturbative large N contribution to the ABJM free energy on 3-sphere. The 1-loop instanton M2 brane partition function was shown in arXiv:2307.14112 to match the localization prediction. The 2-loop computation is complicated by the presence of bosonic and fermionic zero modes, which require using projected Green’s functions and accounting for the collective-coordinate Jacobian. The Jacobian provides a non-trivial 2-loop contribution in addition to the one of the quartic interaction vertex in the M2 brane action. We find that for k ą 2 the transcendental k-dependence of the quartic vertex contribution is cancelled by the Jacobian contribution for any choice of the separation of the fermionic zero modes from the quantum fields. The residual rational term depends on this choice and vanishes for the separation selected by the preserved supersymmetry, under which the collective coordinates and the quantum fields form separate supermultiplets. We conjecture that the remaining integral over the M2 brane instanton collective coordinates contributes just to overall normalization of the partition function so that it is 1-loop exact. For k " 1 the quartic vertex contribution reduces to equation-of-motion terms as in the case of AdS3 Ă AdS7 ˆ S[4] in arXiv:2511.22306 related to S[3] Ă AdS4 ˆ S[7] case by a formal analytic continuation.