Hittade lite på google:
http://lovehorsepower.com/joomla/index.php?option=com_content&view=article&id=47:subaru-legacy-coolant-temperature-sensor-replacement&catid=10:subaru-legacy&Itemid=63

Även detta:

Hittade en matnyttig tråd här:http://www.batauto.com/Forums/index.php?topic=9622.0

Found this for you!! Grin
How to Read Trouble Codes From the ECU

NOTE: These instructions are only for the 90-94 Legacies with an OBD I computer. If you have a 95 or later Legacy, you will need a scan tool or will need to have the dealer read the codes.

On the gauge cluster, to the top left there are a few idiot lights which are not on under normal driving conditions. One of these lights reads ‘check engine.’ This light comes on when the ECU detects a fault in one of the many electronic components from which it receives signals and to which it transmits signals. If the ECU recognizes a problem while the car is on, the ‘check engine’ light will be constantly illuminated. If it has detected a problem in the past, but the problem which it detected no longer exists, the light will be out. However, the ECU will store a record of the faults it has detected in the past until they are cleared deliberately or unintentionally. To read any current or past faults, the ‘check engine’ light will flash in a sort of Morse code, which we can decipher.

Underneath the steering column is a wide rectangular piece of plastic, the same color as the dash, which has a tray marked ‘TRAY.’ This large piece is held to the underside of the dash with a bunch of screws. Remove these screws and remove the plastic piece. Now there will be a bunch of wires for you to see. To the left of the steering column (at least in left hand drive cars) somewhere probably tucked away will be a bundle of wires with two pairs of electrical connectors which are disconnected. On some 92-94 MY Legacies the check connectors can be found on the right hand side of the steering column. One is black and connects one wire to one wire, the other is green and roughly ‘T’ shaped, this one also connects one wire to one wire. With the car turned completely off, connect the black connector. Next, turn the ignition to ‘ON’ but do not start the car. The idiot lights in the dash will come on, and some may go out after a few moments. Watch the ‘check engine’ light and maybe have something you can write on to remember the codes. If there is a fault code in the ECU, the ‘check engine’ light will begin to flash in a particular manner. The codes range in number from 11 to 52, so we know that they all will be two digits. To signify the tens place of the number, the ‘check engine’ light will flash a long (1.2 seconds) flash. The single digit will be a short (.2 seconds) flash. Each flash within the same code will be separated by .3 seconds. Each error code will be separated by 1.8 seconds. Don’t bother trying to time all these, just watch the light and you will begin to understand. Once the ECU has flashed all stored codes, it will loop through and repeat them. Now, for example, you see two long flashes followed by two short flashes. This means you have a code number 22. By looking at the following chart, we see that 22 is the code for the knock sensor. Once you have read and recorded all faults, turn the ignition off and disconnect the black connector.

If you have done the above procedure, you will likely wonder what the green T-shaped connectors are for. These are for a more active code reading procedure called D-check mode in the Subaru manuals. To perform D-check, start with both connectors disconnected, start the engine, allow it to warm up, then turn it off. Next, connect the test mode connectors (green T-shape). Turn ignition to ON position without turning on engine. At this point if the check engine light does not come on, it is faulty and must be It is fixed! before continuing. Depress accelerator pedal to floor, return to half throttle and hold for two seconds, then release. Start the engine. Now the light can blink in two different ways. If everything checks out so far, it will blink to indicate a number 01, 02, 03, 04, 05, 06, 07, or 08. If a problem is already detected, it will blink according to the chart below. Either way, your next step will be to drive the car with the test mode connectors connected. You must drive over 7 mph for at least one minute, and shift up to 4th gear if you have a manual tranny. Now, either you will discover any trouble codes, or if you have none it will blink at a steady rate.

How to reset the ECU

The following procedure tells how to erase the trouble codes from the ECU. This procedure will NOT reset the ECU. To reset the ECU follow the procedure below.

ECU clear memory procedure is as follows for auto and manual transmissions:

1. With engine at operating temperature, turn engine off. Place gear shift lever into park (auto transmission cars only).

2. Locate the two ECU check connectors, for most cars they are located under the steering column and consist of a black plastic male and female connector, and a green male female connector. The exact location of the connectors varies with the different year models, but generally they are located under the steering column on the drivers side.
NOTE: sometimes they are still taped over with some small amount of plastic tape, so look hard, they will be there!
With the ignition OFF, connect black to black and green to green.

3. Turn on ignition, do not start the engine, (and for auto transmission, cycle the gearshift lever from park to neutral and back to park), depress the accelerator pedal to full throttle and hold for a few seconds, and then release. Start engine and then drive for at least one minute, keeping road speed above 10 mph.

4. At this point the check engine light should start to flash the all clear signal (steady 1/2 second interval flashes). At this point the ECU’s memory is cleared. If the check engine light does not flash, or indicates some other sequence, there is a fault present in the system, and should be checked for necessary repairs.

5. Once done, stop the car and turn off the engine.

6. Disconnect the plugs.
To completely reset the ECU (TCU as well) you can use one of the following methods. Note: Resetting the ECU does erase the codes in memory. The first method is commonly referred to as the “battery dance”. The second method is to remove the EGI/TCU fuse (fuse 14). Both methods essentually do the same thing, the only difference is that the fuse method only works on the first gen legacies, and you don’t loose your radio presets. You want to perform both these procedures on a “cold” engine. Leave it sit for a while, or overnight and do it in the morning.

1. Disconnect the negative battery terminal cable for 30-45 minutes. Or pull fuse 14 labeled (EGI/TCU) from the fuse panel at the driver’s kick panel for 30-45 minutes.

2. Reconnect the negative battery terminal cable, or re-insert fuse 14.

3. Turn off all your accessories.

4. Start the car, but DO NOT touch the throttle at all.

5. Let the car idle for 10-15 minutes, or until the car is at normal operating temperature. Again, do not touch the throttle.

6. Turn the ignition key to the “OFF” position. That’s it