Catalyzes the ATP- and NADPH-dependent reduction of carboxylic acids to the corresponding aldehydes (PubMed:28719588). Catalyzes the reduction of a very wide range of carboxylic acids, including benzoic acids, heterocyclic, phenylacetic, phenylpropanoic and fatty acid substrates (PubMed:28719588). a carboxylate + ATP + H(+) + NADPH = AMP + an aldehyde + diphosphate + NADP(+) Binds 1 phosphopantetheine covalently. The N-terminal domain likely catalyzes substrate activation by formation of an initial acyl-AMP intermediate, the central region contains the phosphopantetheine attachment site, and the C-terminal domain catalyzes the reduction by NADPH of the intermediate thioester formed from the attack of the phosphopantetheine thiol at the carbonyl carbon of acyl-AMP (By similarity). Large-scale domain motions occur between the adenylation and thiolation states. Phosphopantetheine binding alters the orientation of a key Asp, resulting in a productive orientation of the bound nicotinamide. This ensures that further reduction of the aldehyde product does not occur (PubMed:28719588). Belongs to the ATP-dependent AMP-binding enzyme family. Carboxylic acid reductase subfamily.