EY warned that slowing growth in lending could hamper the 18-country group's ability to recover from the recent financial crisis.
"Given how dependent consumer spending and SME (small and medium-size enterprises) financing are on bank lending in the euro zone, the AQR (asset quality review) could have a material economic impact," said EY's head of financial services, Andy Baldwin, in a report out on Monday.
"The hope is that it clears the decks for banks to support more sustained growth, but, if there is a large capital shortfall, the AQR could deliver a material knock – not enough to drive the region back into recession, but enough to prolong low growth or stagnation."
EY said that a lending constraint of 0.4 percent or more would weaken euro zone economic growth next year – currently seen at 1.8 percent by the European Commission. However, EY warned that a softening bank lending could see that cut back to as little as 0.7 percent.
"The near-term effects of this spring-cleaning on lending are already having an impact," said EY's Robert Cubbage in the report. "It is likely that some banks will adapt their business models by providing less direct lending to corporate customers in favor of advising them on accessing finance from a range of different sources."