This paper presents a new technique for on-line consistency checking of embedded DRAMs. The basic idea is to use the periodic refresh operation for concurrently computing a test characteristic of the memory contents and compare it to a precomputed reference characteristic. Experiments show that the proposed technique significantly reduces the time between the occurence of an error and its detection (error detection latency). It also achieves a very high error coverage at low hardware costs. Therefore it perfectly complements standard on-line checking approaches relying on error detecting codes, where the detection of certain types of errors is guaranteed, but only during READ operations accessing the erroneous data.