AbstractIn this article, we study the a posteriori H1 and L2 error estimates for Crouzeix‐Raviart nonconforming finite volume element discretization of general second‐order elliptic problems in ℝ2. The error estimators yield global upper and local lower bounds. Finally, numerical experiments are performed to illustrate the theoretical findings. © 2009 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2011