Infringement of traffic law Accident

Hello, my friend had an accident on 18.1.2012 where no one was injured. Today on 6.6.2012 he got a warning money better said a letter against traffic regulations ( §24 StVG*)/ Hearing Dear Mr. XXXX You are accused of having started on 18.01.2012 at 10.05 o’clock in xxxxxxx as a driver of the car BMW xxxx, following traffic regulations offence(s): You damaged by disregarding the care required in road traffic other traffic participants by driving up a standing vehicle § 1 para. 2, § 49 StVO; § 24 StVG; 1.4 BKat Remarks: Evidence : Accident photos Witness/receiving official Witness: PHM xxx, PHK xxx, police station xxxx Because of this irregularity(s) a warning money (§§ 56.57 OWiG*) is fixed against them in the amount of 35€ What is the limitation period now? Should one pay this or should one defend oneself here? I hope you have a few tips.