If you are ever in the unpleasant situation where your system simply beeps
when it should be starting up, this list may help guide you toward the
problem. You'll need to know your BIOS manufacturer... This can be found
on the screen when the system used to boot up, or as an EEPROM chip on the
mainboard. This chip is about 1/2 inch by 2 inches, socketed, and has a
shiny label on it that will list the manufacturer. Alternatively, you could
just go through the list one by one until you find a matching code, although
it won't be any fun.
These codes are fairly standardized, but not universal - they should be
used as a basis for beginning troubleshooting. They are not enough by
themselves to provide a diagnosis. Consult a qualified technitian if you have
any questions or before doing anything rash... Some likely sources of failures
are given in parantheses; These are the most likely and intended for those
that aren't sure what the given meaning means.
| Beep Code | Meaning |
| S | Normal, system passes Power On Self Test (POST) |
| 2S | POST error, reference error code on screen. |
| None | Power problem, loose card, or short circuit. |
| Solid Tone | Power problem, loose card, or short circuit. |
| Repeating S | Power problem, loose card, or short circuit. |
| LS | System board failure |
| L2S | Monochrome or CGA card failure |
| L3S | EGA card failure |
| 3L | Keyboard error |
| Beep Code | Meaning |
| SPSP3S | CMOS failure (bad mainboard) |
| SPSP4S | ROM checksum failure (generally bad mainboard) |
| SP2SPS | PIT failure (bad mainboard) |
| SP2SP2S | DMA failure (bad mainboard or card) |
| SP2SP3S | DMA failure (bad mainboard or card) |
| SP3SPS | RAM refresh failure |
| SP3SP3S | RAM failure in first 64k |
| SP4SP2S | RAM parity failure in first 64k |
| SP4SP3S | Fail-Safe Timer (EISA systems only) |
| SP4SP4S | Software NMI port failure (EISA systems only) |
| 2SPxPx | RAM failure in first 64k |
| 3SPSPS | Slave DMA register failure (bad mainboard) |
| 3SPSP2S | Master DMA register failure (bad mainboard) |
| 3SPSP3S | Master interrupt mask register failure (bad mainboard) |
| 3SPSP4S | Slave interrupt mask register failure (bad mainboard) |
| 3SP2SP4S | Keyboard controller failure (generally bad mainboard) |
| 3SP3SP4S | Video memory failure (bad video card) |
| 3SP4SP2S | Video retrace failure (bad video card) |
| 4SP2SPS | Timer failure (bad mainboard) |
| 4SP2SP2S | Shutdown failure |
| 4SP2SP3S | Gate A20 failure (bad mainboard or RAM) |
| 4SP2SP4S | Unexpected interrupt in protected mode |
| 4SP3SPS | RAM failure above 64k |
| 4SP3SP2S | PIT channel 2 failure (bad mainboard) |
| 4SP3SP4S | Realtime clock failure (bad mainboard or battery) |
| 4SP4SPS | Serial port failure |
| 4SP4SP2S | Parallel port failure |
| 4SP4SP3S | Math co-processor failure |