POST Error codes

IBM POST diagnostic code descriptions

The first thing a PC does at start-up, is to run a Power-on Self Test (POST) to test the PC hardware.

If an error is detected, you will observe either a number of audio beeps or an error message displayed on the screen.

The error message tables below summarize the meanings of the error messages or audio beeps which can occur.

Code Description
100 to 199 System boards
200 to 299 Memory
300 to 399 Keyboard
400 to 499 Monochrome display
500 to 599 Color/graphics display
600 to 699 Floppy-disk drive or adapter
700 to 799 Math coprocessor
900 to 999 Parallel printer port
1000 to 1099 Alternate printer adapter
1100 to 1299 Asynchronous communication device, adapter, or port
1300 to 1399 Game port
1400 to 1499 Color/graphics printer
1500 to 1599 Synchronous communication device, adapter, or port
1700 to 1799 Hard drive and/or adapter
1800 to 1899 Expansion unit (XT)
2000 to 2199 Bisynchronous communication adapter
2400 to 2599 EGA system-board video (MCA)
3000 to 3199 LAN adapter
4800 to 4999 Internal modem
7000 to 7099 Phoenix BIOS chips
7300 to 7399 3.5-inch disk drive
8900 to 8999 MIDI adapter
11200 to 11299 SCSI adapter
21000 to 21099 SCSI fixed disk and controller
21500 to 21599 SCSI CD-ROM system

AMI BIOS Beep Codes

Code Description
1 Short Beep System OK
2 Short Beeps Parity error in the first 64 KB of memory
3 Short Beeps Memory failure in the first 64 KB
4 Short Beeps Memory failure in the first 64 KB Operational of memory
or Timer 1 on the motherboard is not functioning
5 Short Beeps The CPU on the motherboard generated an error
6 Short Beeps The keyboard controller may be bad. The BIOS cannot switch to protected mode
7 Short Beeps The CPU generated an exception interrupt
8 Short Beeps The system video adapter is either missing, or its memory is faulty
9 Short Beeps The ROM checksum value does not match the value encoded in the BIOS
10 Short Beeps The shutdown register for CMOS RAM failed
11 Short Beeps The external cache is faulty
1 Long, 3 Short Beeps   Memory Problems
1 Long, 8 Short Beeps Video Card Problems

Phoenix BIOS Beep Codes

Note: Phoenix BIOS emits three sets of beeps, separated by a brief pause.

Code Description
1-1-3 CMOS read/write failure
1-1-4 ROM BIOS checksum error
1-2-1 Programmable interval timer failure
1-2-2 DMA initialisation failure
1-2-3 DMA page register read/write failure
1-3-1 RAM refresh verification failure
1-3-3 First 64k RAM chip or data line failure
1-3-4 First 64k RAM odd/even logic failure
1-4-1 Address line failure first 64k RAM
1-4-2 Parity failure first 64k RAM
2-_-_ Faulty Memory
3-1-_ Faulty Motherboard
3-2-4 Keyboard controller Test failure
3-3-4 Screen initialisation failure
3-4-1 Screen retrace test failure
3-4-2 Search for video ROM in progress
4-2-1 Timer tick interrupt in progress or failure
4-2-2 Shutdown test in progress or failure
4-2-3 Gate A20 failure
4-2-4 Unexpected interrupt in protected mode
4-3-1 RAM test in progress or failure>ffffh
4-3-2 Faulty Motherboard
4-3-3 Interval timer channel 2 test or failure
4-3-4 Time of Day clock test failure
4-4-1 Serial port test or failure
4-4-2 Parallel port test or failure
4-4-3 Math coprocessor test or failure
Low 1-1-2 System Board select failure
Low 1-1-3      Extended CMOS RAM failure

POST beep codes on CompTIA A+ Hardware Core exam
These POST beep codes are covered specifically on the CompTIA A+ Core Hardware Exam:
The system will normally beep one short beep.
Beeps (i.e. steady, short beeps) Power supply may be bad
Long continuous beep tone Memory failure
Steady, long beeps Power supply bad
No beep Power supply bad, system not plugged in,
or power not turned on
No beep If everything seems to be functioning correctly
there may be a problem with the ‘beeper’ itself.
One long, two short beeps Video card failure