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

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

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