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E36 On-Board Computer- Hidden Codes and Tests for the 18-Button OBC

There are many interesting functions available on the E36 OBC that are not documented in the owner's manual, including changing the language of the display. The procedures described here work on my '97 328iC, which has the "upgraded" 18-button OBC - they may work on other models of similar vintage.
Note that the "upgraded" OBC has 18 buttons. If your OBC has fewer buttons, you should look to the directions for the "standard" OBC on on the 11-button OBC page.

Programming the OBC to Display Contents in a Desired Order

When you repeatedly press in on the turn signal stalk, the OBC display cycles through the various information types that it has in memory. The default sequence is: CONSUM1, CONSUM2, EXT. TEMP, SPEED, LIMIT, DIST and TIMER. If you want to change the display order, use the following procedure:

Press in and hold the turn stalk for about 5 seconds. The OBC display will change to Prog 1. Press the button corresponding to the first function you would like to have displayed in the sequence. For example, if you would like the outside temperature to be displayed first, press the TEMP button. The display will then change to Prog 2. Continue pressing the OBC buttons in the order you want, up through nine entries. You don't have to enter all nine - if you would like the display to cycle only between TEMP and RANGE, simply enter those two items as Prog 1 and Prog 2. When finished, press the SET/RES button to store the sequence in memory.
To revert to the default order, simply press SET/RES as soon as Prog 1 is displayed.

Accessing Data in the OBC

The OBC contains a lot of data, and displays the data in a manner determined by the country code that is stored in it. The technique to access this data is as follows:

  • Press the 1000 and 10 keys simultaneously. You should see Test-Nr: appear in the display.
  • The table below lists the available test codes that are available. Enter a test code number, using the number keys, followed by the SET/RES key. However, to access codes other than 1, 10, 14, 19 and 21 you have to first unlock the OBC, using the procedure described below.
  • Read the results.
  • For test numbers 10 and 11, enter a new value (if desired) and press SET/RES.
  • Return to the nomal display functions by pressing CHECK or any other key.
Unlock the Display. Most of the test sequences require you to first unlock the display before. Enter test code 19 using the above procedure. The display should read LOCK: ON. Then enter an unlocking code consisting of the sum of the current month plus date (for example, if today is July 11, enter 18). Then press SET/RES, and the OBC is now unlocked.

Test CodesFollowing is a list of the available tests, along with with my notes as to what I think each test means. Note that the display uses European conventions for decimals (i.e., the number 61,7 is 61.7 for us Americans).

Test Code No.
Display Must Be Unlocked First?
All LED display elements are lit
Verify that the display is working properly
VBR: n,n l/100km
n,n = instantaneous fuel usage in liters/100 km
VBR: n,n l/h
n,n = instantaneous fuel usage in liters per hour
RW-VBR: n,n l/100
n,n = average fuel usage in liter/100 km.
RW: nnn km
nnn = range in km
Not used
TMTL: nn,n l
nn,n = fuel remaining (in liters)
V: n km/h
n = instantaneous speed in km/h
UB: nn,nn V
nn,nn = system voltage (should be around 13,80)
LAND: n xxx *
Country code -- for US drivers should be set to 2 description below
EINHEIT n: xx *
?? There are two EINHEIT displays: the values for xx in EINHEIT 1 can range between B0 and BF, and for EINHEIT 2 range between 0F and FF (mine is set to B3 and FF, respectively). Press the 1000 or 100 key to switch between EINHEIT 1 and EINHEIT 2.
VANK nn km/h
nn = average speed
ANK: nn:nn
nn:nn = ETA (will display --:-- if the OBC's distance function is not in use)
ROM: = Software version date. Mine is 25.06.1991
DIAG: nn nn nnn xx
Diagnosis code? Mine is 01 05 255 FA
PORT: nn nnnnnnnn
Port codes? Press 1000 or 100 key to cycle port numbers. For example, PORT 01 is 10101000
PROM: nn nn
?? Mine reads 00 12
HORN: xxxx
DTON or DTOFF? (Single tone horn versus dual tone)
LOCK: xx
xx = ON or OFF. See description abovefor method.
KVBR: nnnn
nnnn = Fuel rate calibration factor. Mine is set to 1000
Reset all defect codes? Also erases all stored values in the OBC (i.e, fuel consumption, avg. speed, timer, etc) and clock.

Setting the Country Code. If your OBC suddenly starts displaying everything in German, and you would like to put it back to English, use test sequence number 10. Once you're into test number 10, press the 1key several times, and you'll see the display cycle through various country options. For example, 0 is for Germany (the display reads LAND: 0 D *- I assume D stands for Deutschland). As you cycle through the options, you'll see choices for the USA, France, Canada, etc. Once the display is on the country you want, press the SET/RES key to store your choice into memory -- for US drivers the display should be set to LAND: 2 USA * . Then press the CHECK key, and the display will reflect the units of the country you've chosen.

Information on other OBCs. If your E36 has the "standard" OBC - not the upgraded OBC -you can reset the language of the display using the procedure on the 7-Button OBC Page.