see also:

• taking the Subaru Outback off road

• Subaru Outback 2006 fuse box diagram
  • the 15A blue 2nd row from top, far right Engine Control Unit fuse which activates the fuel pump via a fuel pump relay and fuse in engine bay and also the spark plug ignition system, the ECU fuse is shared with the air bag system and automatic transmission system

• Subaru XV fuse box diagrams

• Subaru Impreza 2014 fuse box diagram
  • fuel pump 15A in engine bay
  • ECU 7.5A in engine bay

• there is no specific fuse as it is controlled by the ECU
• they use a specially designed starter motor and battery with features to support rapid and frequent restarts
  • these starters include tandem solenoids and an inrush current reduction (ICR) relay. The ICR relay stabilizes power supply and reduces the initial rush of current to the starter motor, which helps prevent electrical system voltage dips during repeated engine starts. Peak current may be less than 200A.
  • they are also designed to quickly engage and disengage the engine's flywheel even while the engine is still rotating
  • two main types of batteries are used: Enhanced Flooded Batteries (EFB) for entry-level start-stop systems, and more advanced Absorbent Glass Mat (AGM) batteries for higher-end or more complex systems
    • provide higher cycle battery life, improved charge acceptance, and greater durability to withstand frequent restarting without premature failure
    • can operate efficiently with partial charge states and effectively store energy recovered from braking systems (regenerative braking), enhancing overall energy efficiency
• failure to engage stopping the engine may be caused by:
  • auto-start-stop button is turned off
  • accelerator pedal depressed
  • insufficient brake pedal pressure
  • reversing then stopping
  • car is on an incline
  • a low-voltage battery
  • insufficient engine operating temperature - a cold engine is inefficient and hence start stop defeats the purpose of warming it up by stopping it
  • cabin temperature not at user's target temperature - ie. air conditioner or heater not yet adequately reached target temp
  • an improperly closed hood or door
  • an unbuckled seatbelt
  • ABS sensor fault
  • old battery
  • dirty battery terminal
  • faulty battery sensor
  • water in the fuel tank
  • clogged diesel particulate filter (for diesel engines)
  • check engine lights or codes activated
  • a disconnected engine component
  • need for a TCM software update
• failure to re-start the engine after it stopped it:
  • old battery
  • dirty battery terminal
  • faulty battery sensor
  • gear is in reverse
  • no brake pressure
  • seatbelt not buckled
  • other causes?

• in general one should get the computer read and checked, although often they are just temporary glitches
• one can often reset the error messages by disconnecting battery (black terminal) for 10 minutes although the messages may recur if there is an ongoing issue.

• when all of these suddenly light up and stay on and the Cruise control no longer works but just blinks then:
  • most likely problem is the petrol cap is loose or not replaced correctly!
  • there may be other causes such as:
    • worn seal around petrol cap
    • may be an issue after a flat battery - hmmm…not sure on this
    • the inhibitor safety switch broken
    • check the error code:
      • Po456 indicates an evaporative leak in the system such as a loose or worn petrol cap, and if not these may need smoke testing to find the leak such as in a cracked hose

• this is a real pain and only likely to occur on cars with lots of travel especially on dusty roads
• see my blog on how to replace one with a second hand one (as long as air bags did not go off in an accident)
  • http://www.ayton.id.au/wp02/?p=9493