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How to clear the fault codes on your Subaru including Legacy’s and Impreza’s

Most cars simply store fault codes and that’s it. Subaru’s on the other hand have 2 modes. You can read the stored fault codes or you can check them while the car is driven. This is useful if you have a fault code that only appears when you drive and doesn't hang about long enough to be stored.

Reading and clearing the codes themselves is pretty easy. This method should work on all Pre 1999 Subaru’s with proper ECUs (so if you have a 1978 Brat pick up you don't need to read any more!) After 1999 Subaru began using the EOBD system on their UK cars. I am not 100% sure if the imports after 1999 can still be read like this. No harm in trying I suppose!

How to read the stored codes. Do this before you try the dynamic method.

  1. Turn the ignition off
  2. Find the diagnostic connectors. They are usually under the dash on the drivers side near the centre console. There should be a pair of black connectors (1), a pair of green (2)and a big yellow one (3 We don't need to worry about that!). You are looking for the black pair.
  3. Connect the black connectors together.
  4. Turn the ignition on but don't start it.
  5. Check the engine management light comes on. If it doesn't some snake in the grass has disconnected it! This happens because people are scared of having to take the car to the dealer to have it fixed!
  6. Count the number of flashes. Long flashes count for 10 and short ones are single units. So the code 38 would be 3 long flashes then 8 quick ones.
  7. If it just flashes long flashes continually there are no codes stored.
  8. Anyway, count the flashes and check against the list below.
  9. Turn the ignition back off then disconnect the black connectors. If you mess things up just disconnect the black connectors and start again.

Fault codes
1111      No codes stored
11        Crankshaft position sensor (Don't confuse with above, usually when the crankshaft sensor if dodgy the thing won't start anyway)
12       Starter switch faulty
13       Camshaft position sensor
14       Injector no.1
15       Injector no.2
16       Injector no.3
17       Injector (You guessed it!) No.4
21       Engine temp sensor
22       Knock sensor
23       Mass air flow sensor
24       Idle air control sensor (usually accompanied by running too fast/slow)
31       Throttle position sensor
32       O2 sensor
33       Vehicle speed sensor
35       Emissions canister purge valve
38       Torque control signal (Automatics)
42       Closed throttle position
44       Turbo waste gate regulator malfunction
45       MAP sensor
49       CO adjustment resistor for older cars not fitted with cats
51       Neutral switch (Manual gearbox)

Remember just because the fault code states a component it does not automatically mean that part is knackered. ALWAYS check the wiring, connectors and battery terminals etc. before galloping down to the dealer with your wallet flapping!

Dynamic mode

  1. Get the engine to operating temperature, when the cooling fans have just switched off.
  2. Turn the car and ignition off. 
  3. Connect the green connectors this time (No.2 in the picture)
  4. Switch the ignition on but don't fire it up or it won't work!
  5. Check the management light is on. If it is you can start it up.
  6. If the light doesn't flash drive the car above 10mph for about a minute, no less than 30 seconds.
  7. Stop driving and rev the car up to 2000rpm for at least a minute (this is great when you have an Impreza Turbo with a big exhaust!)
  8. Count the flashes on the management light. Remember a long flash is 10 and a quick flash is 1.
  9. Compare the code to the list above.
  10. Turn the ignition off and disconnect the green connectors. 
  11. That’s you!

How to clear them!

  1. Make sure the engine is up to normal temperature (the cooling fans have just turned off)
  2. Turn the ignition off
  3. Connect the green connectors together 
  4. and connect the black ones together too
  5. Switch the ignition on but don't start it.
  6. Check the management light is on.
  7. Drive the car for about a minute above 10mph
  8. Stop and rev the car to at least 2000 revs for at least a minute
  9. Check the light flashes 4 long flashes (Indicating fault code 1111)
  10. Switch the ignition off and disconnect the green and black plugs
  11. That’s you! Easy wasn't it?