Contents
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
Turn ignition OFF & Disconnect Connectors
If there is a fault Check
Appropriate Sensor
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
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.
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)
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 |
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 |
Sensors
All Sensors
Under
bonnet view of all sensors
Individual Sensors
Sensor
|
Diagnostics
|
|
- |
Starter switch is abnormal |
|
- |
Neutral position switch is abnormal.(AT) |
|
Wastegate control solenoid valve is not functioning |
|
|
Pressure sensor is abnormal |
|
|
Pressure exchange solenoid valve is not functioning |
|
|
Mass air flow sensor signal is abnormal |
|
|
Oxygen sensor is not functioning |
|
|
Vehicle speed sensor 2 is not functioning |
|
|
Engine coolant temperature sensor signal is abnormal |
|
|
Throttle position sensor signal is abnormal |
|
|
Idle switch signal is abnormal |
|
|
Idle air control solenoid valve is not functioning |
|
|
Knock sensor signal is abnormal |
|
|
No signal from camshaft position sensor, but signal from crankshaft position sensor |
|
|
No signal from crankshaft position sensor when starter switch is ON |
|
|
Purge control solenoid valve is not functioning |
Contact Information
E-mail
address
Chris.Palmer@mailcity.com or Chris.Palmer@saxonfields.freeserve.co.uk
Web
address
Last
revised: Date : 31st August 2004