PS/2 Error Codes

POST Error Codes
   Beep Codes
   General Error Codes
   IML Error Codes (I999xxxx/0999xxxx)
   SCSI Error Codes

Troubleshooting Hints
   POST Errors
     Multiple POST Errors
   Dead System
     Troubleshooting Dead System
   Clearing the 96 8N1 code

This page is about one of the most annoying things in the PS/2 World - Error codes. They come up when you need them the least and -often- don't tell much why anything went wrong.

Now here's a collection of the most common error codes along with some explanation and which action to take or which part to change.

POST Error Codes

Beep Codes

*Normal Operation
* *A problem exists, check config. Run diags, if no error code displayed
_ *Display or display adapter problem.
_ * *Display or display adapter problem.
_ * * *Display or display adapter problem.
* * * * * *Continuous short beeps. Check keyboard.
___________Continuous solid beep. System board.

(* indicates a short beep, _ means a long beep)

General Error Codes (from Peter's page)

Major Error Code -----------+---+
                            |   |
                            |   |
Trailing Zeros   -------- 0024 01XX
to fill 8 digits                 ||
Minor (diagnostic Error Code)----++

The Error Code is written in the 4 + 4 style as it appears on the PS/2 Model 95 LED panel and in the Premium Line "extended 8-digits" form. The bold part in the middle is the so called "Major Error Code" and -basically and in large parts- identical with the PC/AT Error Codes and those used on earlier PS/2 machines.

The 2 digits of the "Minor Error Code" is dependent on the type of the error and -mostly- only specified when running the Advanced Diagnostics. The minor error code is however often given at POST-Errors (after restarting the computer) and might specify a particular error condition. In case the minor error code is marked with "XX" in the follow-up error lists it means "Don't care" and it can be any character.

Error messages generally consist of eight characters. If an error message appears as a 12-character message, disregard the last four characters.

The following errors are all listed as eight-character messages. Messages might appear on your screen as three-, four-, or five-character messages. When this occurs, always add two zeros ["00"] to the RIGHT of the code, and add enough zeros "0" to the LEFT of the code to reach eight characters.

Error Code Format Examples

00030100 - Three-character, Codes 300 - 999
00170100 - Four-character, Codes 1500 - 2999
01668000 - Five-character, Codes 15000 - 19999

Error Code Listings

Error Codes 100 - 159
Error Codes 160 - 199
Error Codes 200 - 299
Error Codes 300 - 999
Error Codes 1000 - 1499
Error Codes 1500 - 2999
Error Codes 3000 - 9999
Error Codes 10000 - 11999
Error Codes 12000 - 14999
Error Codes 15000 - 19999
Error Codes 20000 - 29999

Single-page Error Code List (incomplete!)

IML Errors (I999xxxx/0999xxxx)

These have to do with the Initial Microcode Load on the 76/77, 85, 90, 95, and 500 systems (and the TP700/720). See HERE.


These error codes indicate a problem with the SCSI host adapter or one of the attached SCSI devices. See HERE.

Troubleshooting Hints

POST Errors

Refer to the General and SCSI Error Codes above.

If multiple errors occur during POST, resolve them in the order that they are presented.

Note: The correct procedure for using the Personal System/2 reference diskette is to power on the system with the diskette inserted in the diskette drive. Soft booting the reference diskette (i.e. Ctrl-Alt-Del) may cause false errors as well as a false indication that a power-on password is already present when you try to set one.

Ed. I can't remember having issues from a warm boot while working on a PS/2, -BUT- if the system refuses to apply configuration changes, cold boot.

Always cold boot and run Advanced Diagnostics (go into System Programs and at the main menu do a Ctrl-A) before replacing components when trying to resolve software problems. If diags don't fail, replacing components will probably not solve the problem. Refer to the software vendor for possible patches. The software may not be supported on the system.

Multiple POST Error Procedure

If more than one error code is displayed, diagnose the first error code first. The cause of the first error code could cause other devices to fail. This is especially important with configuration errors.

If no error codes appear, see if the error symptoms are listed in the Error list.

If an adapter consists of multiple FRUs (memory for example) remove the optional FRUs one at a time to see if symptoms change before replacing the adapter.

External surge suppressors may be the source for hard to diagnose problems.

Dead System (no POST, screen blank, no beep)

The most likely cause is a device that is shorting out the power supply. An improperly inserted memory module, a defective adapter or device can cause a short circuit. To prevent damage to a power supply, the system board must present a "Power Good" signal to the power supply in 150 ms or less. If this does not occur, then the power supply shuts down internally.

Known dufus tricks- SIMM inserted backwards (with enough force ANYTHING is possible). adapter not fully seated in expansion slot, power cord not plugged in, unsupported/defective adapter (Non-IBM adapter, like ALR), or with a heavily loaded system, too many drives starting at once (overcurrent as the drives attempt to spin up- leave motor start jumper open to start drives after the controller interrogates them).

Troubleshooting a Dead System

  1. Verify that power is on (power cord plugged in?). If the system has power, then go to step 2.

    Note: Intermittent and very difficult to diagnose system problems, may be caused by line cords which are not fully seated, or are too loose to make a tight connection.

    When troubleshooting intermittent post errors, or any unusual, system problems, (for example; system performs power-on reset unexpectedly during operation) check the line cord for proper seating. Slight forming of the male contacts in the system unit power supply connector may correct the problem -OR- you can sometimes adjust the female contacts in the line cord plug.

    Warning! Remove line cord from outlet before working on line cord contacts!

    Replacing the line cord may be necessary in some cases. Both ends of the line cord should be checked.

  2. Remove all adapters, options, extra memory, etc.
    Remove all external connections, KB, mouse, display, etc.

  3. Plug in, power on, listen for a beep. The beep indicates POST has run.
    Multiple beeps may occur.

  4. A) If no beep is heard, verify continuity through speaker.
    If OK, replace system board memory and retry # 3.
    If still no beep, verify PSU voltages. If voltages are OK, replace system board.
    If voltages are incorrect, replace the power supply. 85/95 PS 90 PS 500 PS

    Note: On systems with LogicLock, the switches used to detect unauthorized access might be put in the wrong position during case re-installation.

    Unit does not run with cover removed (9556/57 9576/77)

    B) If a beep occurs, reinstall adapters one at a time and return to step 3. When something is added and the beep is no longer heard, the last item plugged in is probably defective. At this point, it is not necessary to reconfigure the system each time an adapter or device is added because we expect any beep.


Defective or weak batteries can cause loss of all setup information. If only part of the setup is lost, the battery is probably NOT the cause. Inaccurate time is usually caused by software, but some of the older models with the 6V batteries are more prone to time slowing down.

Clearing 96 8N1 (from Peter Wendt)

IBM says "Replace the battery and restart the system." See HMM, Oct 1994 - "96 8N1 Error Message"(page 446 physical). Empirical evidence tells a different story however.

Shortening the battery connectors (with the battery removed of course) *and* toggling the startup password jumper seems to be the only fast cure. There seems to be a board logic, that ANDs the two conditions after a power-on and deletes the entire setup from the CMOS.

At least during the "hot phase" when the Model 90/95 machines could be found in larger quantities at various customers this procedure was the only one that worked reliably and fast enough. And I had quite a few 95s under service...

That worked every time I'd end in the "ASCII console mode" when fiddling with various complex upgrades. Moving only the jumper or only isolating the battery often did *not* cure it. Which is rather strange.

Password Jumper

Info about the password jumper HERE.

Content created and/or collected by:
Louis F. Ohland, Peter H. Wendt, David L. Beem, William R. Walsh, Tatsuo Sunagawa, Tomáš Slavotínek, Jim Shorney, Tim N. Clarke, Kevin Bowling, and many others.

Ardent Tool of Capitalism is maintained by Tomáš Slavotínek.
Last update: 08 May 2024 - Changelog | About | Legal & Contact