Set the left side high and right side to low on your climate control - now here's the fun part. - pasted from another thread

Ignition ON
Temperature selector left "HI", right "LO".
Within 20 seconds, press REST and EC simultaneously for more than 5 seconds
The led in the RECIRCULATE button flashes and the display shows "di R"
Press AUTO repeatedly until all DTC's (refer to DTC table) are displayed. Record each DTC as it is displayed.
Each malfunction (short circuit, open circuit, etc.) has a specific DTC assigned to it.
The letter "E" (Error) is displayed in the left side of the display and the DTC is displayed in the right side of the display. By pressing the right AUTO button, the next DTC stored in memory will be displayed.

To erase: Only possible after all DTC's are read out. Simultaneously press both AUTO > 2 secs. "d" will be displayed in the left side of the display window and "FF" on the right side.
To cancel erase: By pressing AUTO the current faults will appear again.

Set temperature selector to normal setting.
Turn ignition OFF to end test.

DCT table:

B1226 - In-car temperature sensor (B10/4)
B1227 - Outside temperature indicator temperature sensor (B14)
B1228 - Heater core temperature (B10/1)
B1229 - Heater core temperature (B10/1)
B1230 - Evaporator temperature sensor (B10/6)
B1231 - ECT sensor (B11/4)
B1232 - Refrigerant pressure sensor (B12)
B1233 - Refrigerant temperature sensor (B12/1)
B1234 - Sun sensor (B32)
B1235 - Emissions sensor (B31)
B1241 - Refrigerant fill
B1416 - Coolant circulation pump (M13)
B1417 - Duovalve (Y21y1), left
B1418 - Duovalve (Y21y2), right
B1419 - Electromagnetic clutch (A9k1)
B1420 - Idle speed increase
B1421 - Pulse module (N65)
B1422 - Series interface (K1) connection to instrument cluster (A1)
B1423 - Switchover valve block (Y11)
B1424 - Activated charcoal filter actuator (A32m2) open
B1425 - Activated charcoal filter actuator (A32m2) closed
B1432 - Non-USA DTC
B1459 - Series interface (K2) connection to instrument cluster (A1)
B1462 - Wide open throttle (WOT) position signal: diesel engines

__________________
1991 190E 311K [Brilliant Silver/Black MBTEx] -retired
1996 E300 315K [Black/Grey MBTex]

Want to put a tank in the trunk for WVO/SVO in the E300 Need to find a place to store my OIL!
Still procrastinating about the biodiesel/WVO
Made some biodiesel but so afraid to pour it all in - I've added some and think I'll supplement my fuel to see how I make out

Made some biodiesel but the process scares me - methanol fumes are not your friend! Need to do this outside.