  Asymptotic Giant Branch (AGB) stars shed a significant amount of their mass
in the form of a stellar wind, creating a vast circumstellar envelope (CSE).
Owing to the ideal combination of relatively high densities and cool
temperatures, CSEs serve as rich astrochemical laboratories. {While the
chemical structure of AGB outflows has been modelled and analysed in detail for
specific physical setups, there is a lack of understanding regarding the impact
of changes in the physical environment on chemical abundances. A systematic
sensitivity study is necessary to comprehend the nuances in the physical
parameter space, given the complexity of the chemistry. This is crucial for
estimating uncertainties associated with simulations and observations. In this
work, we present the first sensitivity study of the impact of varying outflow
densities and temperature profiles on the chemistry. With the use of a chemical
kinetics model, we report on the uncertainty in abundances, given a specific
uncertainty on the physical parameters. }Additionally, we analyse the molecular
envelope extent of parent species and compare our findings to observational
studies. Mapping the impact of differences in physical parameters throughout
the CSE on the chemistry is a strong aid to observational studies.
