Subaru ImprezaECU Diagnostics

The ECU can diagnose any fault that may arise due to abnormal signals that are sent to the controller. The ECU Check Engine Light (CEL) will illuminate in the instrument console if there is a problem with any of the computers inputs.  It is possible to find which sensor is faulty by following these steps:

Turn ignition OFF. Connect read memory connectors. These are the small black connectors under the

steering column above the pedals.

Turn ignition key to the ON position (Engine OFF)

Engine Check Light turns on

Code is indicated by Pulsing light - See below

If Code is OK Turn ignition OFF disconnect the black connectors

If CEL returns a number of different pulsing lights then check the ECU code table.

Turn ignition to the OFF position. Disconnect the black connectors.

If there is a fault, then check the appropriate sensor.

The ECU codes are displayed as pulses of the CEL.  If CEL goes out there is no fault. 

In Diagnostic Mode – No Fault is indicated by the CEL continuously & evenly flashing on/off (this is also used to indicate the successful completion of an ECU Reset) SEE "OK code" in diagram below.

The long pulses (1.3 Seconds) indicate Tens and the short pulses (0.2 Seconds) indicate ones. Pulses are separated by Short Pauses (0.2 Seconds), multiple codes are separated by a Long Pause (1.8 Seconds) SEE "Trouble codes" in diagram & examples below.

The simplest way for an inexperienced mechanic to retrieve codes is to write the codes down in a sort of Morse Code (dots and dashes), and start a new line when you get a 1.8 Second pause (for NEW code), and then add the actual numbers up after code retrieval is completed. 

 

Code example = Single code

1.3 second pulse (10) 0.2 second pause 1.3 second pulse (10....for a total of 20) 0.2 second pause 0.2 second pulse (1.....for a total of 21) 0.2 second pause 0.2 second pulse (1.....for a total of 22) 0.2 second pause 0.2 second pulse (1.....for a total of 23)

(Code 23 = MAF Sensor)

 

Code example = Multiple codes

1.3 second pulse (10) 0.2 second pause 0.2 second pulse (1.....for a total of 11) 0.2 second pause 0.2 second pulse (1.....for a total of 12)0.2 second pause 0.2 second pulse (1.....for a total of 13)

(Code 13 = Camshaft sensor)

1.8 second pause (this means NEW code)

1.3 second pulse (10) 0.2 second pause 1.3 second pulse (10....for a total of 20) 0.2 second pause 0.2 second pulse (1.....for a total of 21)

(Code 21 = Coolant sensor)

 

These numbers refer to the sensors listed below which are in fault or have recorded a fault on the ECU.

 

Code ITEM 11 Crankshaft position sensor12 Starter switch13 Camshaft position sensor 21 Engine coolant temperature

sensor22 Knock sensor 23 Mass air flow sensor24 Idle air control solenoid 31 Throttle position sensor 32 Oxygen sensor 33 Vehicle speed sensor 2 35 Purge control solenoid valve 42 Idle switch44 Wastegate control solenoid

valve 45 Pressure sensor – Pressure

exchange solenoid valve

51 Neutral position switch

 

ECU Reset

NOTE: This is only applicable to MY93-00 (GCA) models. The later model MY01 (GDA) onwards require the use of a product such as the DeltaDash or similar to reset the ECU. Please see www.ecutek.com.au/delta-dash.htm  for more information.

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 11 Km/h.

4. ECU is now re-set. 5. At this point the check engine light should start to flash the all clear signal (steady 1/2

second interval flashes). If the check engine light does not flash, or indicates some other sequence, there is a fault present in the system, and should be professionally checked for necessary repairs.

6. Once, stop the car and turn off the engine. 7. Disconnect the plugs. 8. Job complete.