U1134 lin no communication with the voltage retaining device

[Mdrwtt]

Hi this message appeared yesterday with a red engine stop light on U1134 lin no communication with the voltage retaining device the alternator is still charging the battery and cars running ok can you help me in the right direction of what this could be ive been reading it's something to do with the start stop system my vin number is VF7**************[VIN obfuscated, can be read by forum staff] it's a ds5 Thanks