I saw a similar post to this but I think I have different symptoms.
My Fuse #12: lower cigar lighter and OBDII plug goes out frequently.
I just changed it to a new 20AMP and within an hour it was blown out again.
I have my sirius radio connected to the lower cigar lighter and my ScanGauge2 connected to the ODBII.
This is the first time that it has blow within the hour of installing a new fuse.
Typically it will last a few weeks.
Do you think this is pulling too much power or do I have a short somewhere?