As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING FLIGHT NR 3557, NR 1 ENGINE OIL LOW PRESSURE LIGHT CYCLING ALL OTHER INDICATION NORMAL. AIR RETURN TO MSP. MAINTENANCE REPLACED PROCESSOR PN/ON-OFF 2-303-864-02, SN/OFF 10130700411 SN/ON 020130700436 IAW AMM 77-40-01 OPS CHECKS GOOD MXC NR 4103 NOTIFIED.