If an officer issues a citation under section 742 for a civil infraction or if a citation is issued under section 742 for a parking or standing violation, the court may accept an admission with explanation or an admission or denial of responsibility upon the citation without the necessity of a sworn complaint. If the person denies responsibility for the civil infraction, further proceedings shall not be had until a sworn complaint is filed with the court. A warrant for arrest under section 321a for failure to appear on the civil infraction citation shall not issue until a sworn complaint relative to the civil infraction is filed with the court.