ECU Diagnostics, Reset, Error Codes & Sensors Page

Contents

*   ECU Diagnostics

*   ECU Reset

*   Finding those Connectors

*   Reading ECU Codes

*   Impreza ECU Codes

*   Other Subaru ECU Codes

*   Sensors

*   Contact Information

 

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ECU Diagnostics

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

*   Turn ignition OFF

*   Connect read memory connectors
(jumper 5) [black connectors]

*   Turn ignition ON (Engine OFF)

*   Engine Check lamp turns on

*   Code is indicated by Pulsing lamp

*   If Code is OK then Turn ignition OFF & Disconnect Connectors

*   Check ECU Code

*   Turn ignition OFF & Disconnect Connectors

*   If there is a fault Check Appropriate Sensor

 

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ECU Reset

On early MYs (especially pre MY97) the ECU retards the ignition when knock is detected, however, it is very slow to advance the timing again. An ECU reset will restore the car to factory default settings.  This will remove any stored fault codes and restore ignition advance.  It is possible to reset the ECU by following these steps:

*   Turn ignition OFF

*   Connect Read Memory Connectors & Test Mode Connectors
(jumper 5) [black connectors] – (jumper 6) [green connectors]

*   Turn ignition ON (engine off)

*   Engine Check lamp turns on

*   Depress accelerator pedal completely

*   Then return it to the half-throttle position and hold it there for two seconds

*   Release pedal completely

*   Start engine

*   Code is indicated by Pulsing lamp

*   If a fault is detected - Check ECU Code

*   If no fault is detected - drive the car sensible for a couple of minutes
i.e. until warm (do not run tall & do not thrash it!)

*   When the ECU has been reset the Check Engine Light will flash

*   Code is indicated by Pulsing lamp

*   If a fault is detected Check ECU Code

*   Turn ignition OFF & Disconnect Connectors

*   If there is a fault Check Appropriate Sensor

 

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Finding Those Connectors

As said above, in order to perform diagnostic & ECU resets you need to find the Black Read Memory Connectors & the Green Test mode Connectors (alternatively there is the dash option shown above but this is even more tricky). The connectors are located under the dash up by the steering column. If they have not been used before they are usually taped quite high up & can be difficult to find, but they are there, once untaped they dangle down and are quite easy to use. Here is a poor photograph of the Black Read Memory Connectors & Green Test Mode Connectors on my Scooby.

 

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Reading ECU Codes

The ECU codes are displayed as pulses of the Check Engine Light.

If Check Engine Light goes out there is no fault.

In Diagnostic Mode – No Fault is indicated by the Check Engine Light continuously & evenly flashing on/off (this is also used to indicate the successful completion of an ECU Reset).

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).

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.

(See Example Below)

--- 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 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)

1.8 second pause (this means NEW code)

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

(Codes 23 and 12, MAF Sensor and Starter Circuit)

 

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Impreza Codes

These are the Impreza Error codes that are documented in the Workshop Manual & Stored in the ECU. 

Note – not all error codes are not stored and are not documented (though they are all decoded by a Select Monitor) some of these may be found in the next section.

Code

ITEM

11

Crankshaft position sensor

12

Starter switch

13

Camshaft position sensor

21

Engine coolant temperature sensor

22

Knock sensor

23

Mass air flow sensor

24

Idle air control solenoid

31

Throttle position sensor

32

Oxygen sensor

33

Vehicle speed sensor 2

35

Purge control solenoid valve

42

Idle switch

44

Wastegate control solenoid valve

45

Pressure sensor –Pressure exchange solenoid valve

51

Neutral position switch

 

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Other Subaru Codes

These codes are not documented in the Impreza Workshop manual but are mentioned in other Subaru Documentation (and can be decoded by a Select Monitor), these may or may not be applicable to the Impreza.

Code

ITEM

11

Crank Angle Sensor or Circuit

12

Starter Switch or Circuit

13

Cam Position Sensor or Circuit (TDC Sensor on Justy)

14

Fuel Injector No. 1 (Legacy, Impreza, Justy, SVX)

15

Fuel Injector No. 2 (Legacy, Impreza, Justy, SVX)

16

Fuel Injector No. 3 (Legacy, Impreza, Justy, SVX)

17

Fuel Injector No. 4 (Legacy, Impreza, SVX)

18

Fuel Injector No. 5 (SVX)

19

Fuel Injector No. 6 (SVX)

21

Coolant Temperature Sensor or Circuit

22

Knock Sensor or Circuit (Right Side on SVX)

23

Air Flow Meter or Circuit (Exc. Justy)

24

Air Control Valve or Circuit (Exc. Justy)

25

Fuel injector No. 3 and 4 (XT-6)

26

Air Temperature Sensor (Justy)

28

Knock Sensor No. 2 (SVX, Left Side)

29

Crank Angle Sensor (SVX, No. 2)

31

Throttle Position Sensor or Circuit

32

Oxygen Sensor or Circuit (No. 1, Right Side, On SVX)

33

Vehicle Speed Sensor (VSS) or Circuit

34

EGR Solenoid or Circuit

35

Purge Control Solenoid or Circuit

36

Air Suction Solenoid Valve (Impreza)

37

Oxygen Sensor (No. 2, Left Side, On SVX)

38

Engine Torque Control (SVX)

41

Air/Fuel Adaptive Control

42

Idle Switch or Circuit

43

Throttle Switch

44

Wastegate Duty Solenoid (Turbo Models)

45

Pressure Sensor Duty Solenoid (Turbo Models)

45

Atmospheric Pressure Sensor or Circuit (Non-Turbo Models)

46

Neutral or Parking Switch or Circuit

47

Fuel Injector

49

Airflow Sensor

51

Neutral Switch (Manual Transmission Models)

51

Inhibitor Switch (Automatic Transmission Models)

52

Parking Brake Switch (Exc. Justy)

53

Fuel Pump or Circuit

54

Choke Control System

55

EGR Temperature Sensor or Circuit

56

EGR System

57

Canister Control System

58

Air Control System

61

Fuel Tank Pressure Control Solenoid (Impreza)

62

Fuel Temperature Sensor (Impreza)

63

Fuel Tank Pressure Sensor (Impreza)

64

Vacuum Line Control Valve or Circuit

65

Vacuum Pressure Sensor

66

Sequential turbo system

67

Exhaust valve solenoid (positive pressure)

68

Exhaust valve duty solenoid

71

Ignition Pulse System

73

Ignition Pulse System

74

Ignition Pulse System

88

TBI Control Unit

 

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Sensors

All Sensors

Under bonnet view of all sensors

Individual Sensors

Sensor

Diagnostics

-

Starter switch is abnormal

-

Neutral position switch is abnormal.(AT)

3

Wastegate control solenoid valve is not functioning

1

Pressure sensor is abnormal

2

Pressure exchange solenoid valve is not functioning

5

Mass air flow sensor signal is abnormal

6

Oxygen sensor is not functioning

7

Vehicle speed sensor 2 is not functioning

8

Engine coolant temperature sensor signal is abnormal

9

Throttle position sensor signal is abnormal

9

Idle switch signal is abnormal

10

Idle air control solenoid valve is not functioning

11

Knock sensor signal is abnormal

12

No signal from camshaft position sensor, but signal from crankshaft position sensor

13

No signal from crankshaft position sensor when starter switch is ON

14

Purge control solenoid valve is not functioning

 

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Contact Information

E-mail address

Chris.Palmer@mailcity.com  or  Chris.Palmer@saxonfields.freeserve.co.uk

Web address

Home Page

 

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Last revised: Date : 31st August 2004