this machine has only done 10k. 8 months old machine.

E020-04A8-05 Toner Density Sensor (Bk) output error
Detection Description The output value of the Toner Density Sensor (Bk) in the Developing Unit (Bk) did not fall within
the range between 38 and 214 for 2 consecutive times during printing.
Remedy [Related parts] R1.00
- Harness between the Toner Density Sensor (Bk) (UN24/J1053) and the Developing Unit (Bk)
(J1043)
- Harness between the Developing Unit (Bk) (J1043) and the DC Controller PCB (UN049/J128)
- Developing Unit (Bk)
- DC Controller PCB (UN049)
[Remedy] Check/replace the related harness/cable, connector and parts.
[Reference] Before replacing the DC Controller PCB, back up the service mode data (approx. 2
min) and restore the backup data after the replacement so the data may be able to be protected.
- Backup: COPIER (LEVEL2)> FUNCTION> SYSTEM> DSRAMBUP
- Restoration: COPIER (LEVEL2)> FUNCTION> SYSTEM> DSRAMRES

I HAVE REPLACED THE BLACK DEV UNIT. SET IT UP OK AND THEN AFTER 30 PRINTS THE ERROR CAME BACK IN.
BLACK PRINT DENSITY QUALITY LOOKS VERY GOOD.

ANY IDEAS???