ERROR: could not read block 4 ...

Hi, I'm getting this error:

2016-09-15 09:35:24 ART [13984-1] ERROR: could not read block 4 in file
"base/12210/11965": Error de entrada/salida
2016-09-15 09:35:39 ART [14082-1] ERROR: could not read block 4 in file
"base/12210/11965": Error de entrada/salida
2016-09-15 09:35:54 ART [14170-1] ERROR: could not read block 4 in file
"base/12210/11965": Error de entrada/salida
2016-09-15 09:36:09 ART [20704-1] ERROR: could not read block 4 in file
"base/12210/11965": Error de entrada/salida

To find out which database points to it I use:

mydb=# select oid, datname from pg_database;
oid | datname
-------+-----------
1 | template1
12210 | template0 <--- Looks like this is the problematic db
12215 | postgres
16384 | mydb

Two questions:

1) Is this caused by a bad block?, can fsck fix it?.
2) Is there a way to re-generate template0?.

Regards,
--
Leonardo M. Ramé
Medical IT - Griensu S.A.
Av. Colón 636 - Piso 8 Of. A
X5000EPT -- Córdoba
Tel.: +54(351)4246924 +54(351)4247788 +54(351)4247979 int. 19
Cel.: +54 9 (011) 40871877