¶ General
This section describes diagnostic trouble codes (DTC's) as well as the different engine computers.
There are software updates available for the engine and transmission computers. Normally installed at the dealership for a fee it's worth having them check for updates before undertaking serious engine or transmission troubleshooting. See the resources page for a list of software updates available from Subaru dealerships, for a fee of course. Its likely worthwhile to have the dealership check for updates prior to troubleshooting issues.
¶ Self Diagnosis for Diagnostic Trouble Codes (DTC's)
You don't need a code reader to see why your check engine light is lit, just follow this procedure. The starting condition is key off, headlight switch off. Steps 1 through 8 must be done within 10 seconds.
- Turn key to ON position. This is the normal running position, the click just before starting, when all the lights on the dash come on, but before you twist to START. Don't start the engine!
- Within 3 seconds, turn the headlight switch ON.
- Press the Trip/Odometer button 4 times.
- Turn the headlight switch OFF.
- Press the Trip/Odometer button 4 times.
- Turn headlight swtich ON.
- Press Trip/Odometer button 4 times. At this point, the DTC display will begin.
- Turn headlight switch OFF. Not necessary for the procedure, but your display may be dimmed and hard to read in bright sunlight. Besides, why drain the battery?
The DTCs for each module will display in order: ECM, TCM, ABSCM/VDCCM. Press the Trip/Odometer button to cycle between modules. The FSM states that the display will cycle between modules automatically every three seconds if the button is not pushed, but that did not happen in my car - I had to push the button to cycle the display. For each module, there are three display states.
Receiving DTC from module (blinking "P" or "C")
DTC detected & displayed ("P" or "C" followed by 4 digits)
No DTC found ("P" or "C" followed by "----")
¶ On Board Diagnostics - OBD-II
The diagnosis port is in the passenger foot well, to remove it press the large tabs either side of the port. The cables can become damaged if the lower panels are moved without disconnecting the port although can be replaced with this unit from iWire services.
¶ Connectivity
This section gets complex so will need more editing. There's different ways to connect your diagnostic device to the vehicle along with regional and model year differences. The table below is based on the RomRaider Logger Communications Settings selection dialogue. See our Gadgetry page for more information about the adaptors and software to run on your laptop or phone.
Later model years of these cars support early versions of CAN bus. You can check if the OBD-II port on your car has pin ? to be sure.
¶ Protocol
| Protocol | Transport | Adaptors | Note | Software |
|---|---|---|---|---|
| OBD-II | CAN bus | SAE J1978 standard for OBD diagnostic modes $01, $02, $03, $04, $05, $06 , $08 | ||
| DS2 | K-Line | ISO 9141, BMW | ||
| SSM | K-Line |
VAG-COM KKL cable ELM 327 Bluetooth |
Generally available adaptors. Ensure VAG cables have the FTDI chip for K-Line communications. | RomRaider, FreeSSM, Cascade |
| SSM | CAN bus | Tactrix 2.0 | SAE J2534 Subaru. Only later models equipped with CAN bus, some ECU's require a software patch for this to work. Much faster for logging and required to flash maps to the ECU. | RomRaider, ECUFlash, FreesSSM |
| NCS | K-Line | SAE J2534 Nissan |
In this context
- VAG refers to the Volkswagen Audi Group who were involved in the standards development
- SSM is Subaru Select Monitor diagnostic software as well as their name for their proprietary communications protocol
¶ Engine Computer
Located under the drivers feet. Under the carpet under a metal shield and removable with a 10mm socket. It's placed on an angle to reduce the chance of water damage.
¶ Problems
These are generally bullet proof tho' in some situations the printed circuit boards can dry out to cause strange misfires, more info here.
¶ Logging
Data can be logged from the many sensors that feed values to the engine computer. See our gadgetry page for more information.
¶ Tuning
Tuning the maps that define the behavior of the engine computer is possible, see our gadgetry page for more information.
¶ Transmission Computer
A common issues for this generation is transmission shift shock which can be fixed, with a dealership software update, see the resource page for more info.
¶ ABS Computer
The car stores the most recent 3 faults in memory.
¶ Body Integrated Computer
¶ Chimes - Seatbelt
If you drive without the seat-belt the car will chime. This can be disabled by following the pattern of repeatedly connecting the seat belt described here. Or if you choose to modify wiring some people have notes here and here.
¶ Chimes - Door Open
¶ Immobilizer, Alarm
The engine computer, body integrated computer and dashboard are coded with an immobilizer code. See this post for more information on how these three components work together and how to reprogram some elements to facilitate engine or ECU swap.
The factory alarm can be turned off or on following the instructions in this video. Get in the car, close the doors and turn the ignition on. Then open the drivers door and quickly - within a second - hold the door mounted unlock switch for 10 seconds. The horn will briefly beep and a message will appear on the info panel to show if the factory alarm is enabled or not. Repeat the process to toggle the alarm enabled or disabled.
¶ Cruise Control
Some models from the factory without cruise control can have this functionality installing later using Subaru parts. See these pages for more info.
¶ Headlight Level Adjustment
If your car doesn't have a dial to adjust headlight height it's likely automatically controlled. If the car has HID headlights this is probably the case.
Automatic headlight level adjustment is managed by a small controller located just behind the top right hand side of the radio head unit. There are height angle sensors on the front left and rear left suspension, see the body section for more info. If these sensors fail a warning light will be shown on the dashboard, however it's possible to delete the warning light by removing the headlight leveling controller if this system is not working for you check this has not been removed. Check also that the headlight leveling light is shown for a couple seconds after turning on the ignition during lamp test.
¶ Alternator
Some models have a 3-pin alternator aka generator in some service manuals. The pins are, from right to left (as from inside the car);
- ECU Control (alt-1)
- Battery Voltage Sense
- Dashboard warning light - charging system (alt-2)
Where ECU Control is wired (not all models) the car computer can reduce the load on the alternator for emissions and efficiency purposes. Some people have wired alt-1 to ground to ensure the battery is being fully charged at all times to address charging system errors or to stabiise voltage for other components such as the fuel pump or injectors.
¶ Clock
This generation of vehicles is known to have an issue with the centre console clock. The display may flicker or lose power completely due to an issue with dry solder joints. The unit can be repaired with these DIY instructions. Note there are a couple of variations of clock depending if the dashboard on the car displays fuel economy and temperature.
¶ Audio and Head Unit
The stock audio configuration depends if the car has dual zone climate control or navigation. The front panels are designed around the centre console which means third part audio is not a direct fit install although is possible. Some right hand drive vehicles in Russia, Australia and New Zealand were exported from Japan after living in Japan for several years. These right hand drive models often have a mix of English and Japanese displayed on the dashboard and console in which case language conversion is not possible.
It is possible to install a single or double din head unit in the top cubby.
It is possible to install an after market double din head unit on single & dual zone climate control models. Subaru make fascia adapter H6217AG911 for this purpose although it is not cheap. Vehicles built in the USA may need this work & wiring described here for the fascia adapter to work properly.
Ever wanted to keep the audio system running after the engine is stopped ? Shift gear into Neutral before turning the engine off.
Some stock head units especially the dual zone A/C models have problems with the lights flickering, see this page for more info.
¶ Interior Lighting
Did you notice that the map light doesn't come on when you open the door to get into the car ? By default only the interior light above the passenger seats does. You can have the map light operate for a brighter welcome if you are handy with a soldering iron, see the instructions here.
Dashboard illumination can be adjusted via the scroll switch nearby the mirror anglel controller. For daytime use with the headlights on align the scroll switch to the small dot for maximum dashboard illlumination.
¶ Wiring Problems
Cables between the body and rear hatch can fail causing issues such as brake, indicator or reverse lights not working or causing the hatch lock mechanism to not operate. Open the hatch to find two rubber sleeves that connect the wiring harness to the hatch. These sleeves can be loosened to allow you to inspect the cables within, often times one or more may have become hard and cracked over time causing a wire to break. These can be repaired in place or the whole rear harness can be purchased and installed.