Detecting data transmission errors in an I2C system that includes a source device, an destination device, and a signal line coupling the I2C source and destination device, including: receiving, by the I2C destination device from the I2C source device, a data transmission signal, the data transmission signal encoded with a set of bits; detecting, by the I2C destination device, rise time of a preselected bit in the set of bits; if the detected rise time is less than a predefined threshold, determining that the I2C source device injected a parity bit in the signal, and if the detected rise time is not less than the predefined threshold, determining that the I2C source device did not inject a parity bit in the signal; and determining whether the data transmission signal includes an error in dependence upon the parity of the set of bits.