Mr B

Only kit to use is the ICP timing belt kit with OEM manufacturer sourced parts. They also do GMB or Aisin water pumps that pretty good (use a oem metal gasket with it) Cost effective and decent parts ... ICP do sell on eBay or via website ... calling them is good option.

If you intend fixing it the quicker the better as longer left like this potentially more engine damage is caused . I have done head gasket only (resurfaced heads) on forester turbo's before and engines lived on fine but partially only due to being pretty confident on engine health prior to doing and fact mileage was fairly low . It be a big gamble at your high mileage doing just head gaskets should that be the issue . If you do decide do head gaskets you want be very selective on parts used and quality of work . The boxer engine is pretty easy to pull and do the heads for someone with experience with them . Option 2 is check the basics and if nothing found assume it head gasket as that the common failure and just live with it for six months to a year while work out a replacement .

It highly likely head gasket the issue, check some basics such as water pump and thermostat housing/hoses for leaks and also radiator and turbo cooling lines (visible coloured staining marks left from antifreeze) You can use chemical test kits detect combustion gases in cooling system (we use gas analyser over rad filler neck) It done some miles and to be honest I wouldn't want do just gaskets at that mileage, bearing shells, all new seals, new oil pump , new rings/pistons and valve overhual tends be best way forward but you could indeed do just head gasket and basic head overhaul if the short block seems decent enough and assemble with new water pump and quality japan timing kit (ICP do these at sensible money) Good parts and good effort won't be that cheap & at this mileage further issues could crop up from fatigued engine stressed from the poor cooling/overheating .

I wouldn't worry too much as it pretty easy and cheap to source used working M30 alarms and swap over faulty modules if that turns out be the case . The alarm siren can be dismantled by hidden recessed screws so battery can be replaced and board can be visually inspected . Main control unit pretty easy swap (just be sure comes with a working fob or 4 pin code so can program your fobs easily) . I have changed a few main control modules and sirens over the last 10 years . You could also remove/bypass or replace with new alarm, lot of owners on more basic old models such as forester and outback don't really want go new alarm route for cost and lowest cost bypass means remote locking lost .

M30 manual if needed > m30.pdf

Yes usually just beeps few times but these old electronics don't always respond how they should . Assume it likely bigger fault but best assuming nothing and inspecting/testing everything starting with basics .

double check bonnet switch not bent out of position or wiring an issue . What did you work on ? was battery disconnected for any period of time . Not unusual for issues with m30 alarms at this age, siren backup battery goes bad and can also leak and corrode board causing odd problems, relays in main unit can go bad too . If Siren issue you can leave siren unplugged and use fob/vehicle like normal . I done some MOT welding work on a Outback last year and had battery disconnect while welding and that drained a failing battery in the Siren . When reconnected battery we had the low dB warning bleeps and after few minuyes alarm would go off randomly. had strip siren and found bad leaking battery that shorting/damaging control board. A decent used siren and a new rechargable battery resolved that one but that was almost couple hours work find fault and chase parts. The fun of electronics lol, hybrids and electric cars be fun if manage reach age of this ...

does switch look like image below Plenty used on ebay . https://www.ebay.co.uk/itm/266845587102 or get new via amayama https://www.amayama.com/en/part/subaru/83322aj010 want check part number/variant before ordering ... (will be a number on back of your switch)

2 use KYB brand. if wait for ebay 20% coupon code you can get them quite cheap ...

Aftermarket quality in suspension parts is a major concern . It also a major safety factor and impacts driving/performing quality of vehicle . ICP aftermarket part quality is a bit hit and miss as they not as fussy as use to be and the aftermarket manufacturing quality is down the toilet these days even on previous well rated major car part brands . So if buying from ICP you wise call them and ask what brand/manufacturer the part is rather than assuming it good . What I do on these if the original arm is not seriously rusted is fit new bushes and new genuine subaru ball joint too. We get the original balljoints for example for about 16 quid so it not worth buying aftermarket to save few quid on a part that serious safety component and needs be proper quality have half a chance of decent service life . For complete arm you could look at ACKOJA, they made in Korea by OEM's for car parts so quality not the worst . MOOG is another option for suspension parts that not the worst . We have to deal with this poor quality part concern every day and aftermarket part quality is the biggest problem we face today, takes lot of knowledge and time keep on top of what good/bad and price effective, you also always getting customers wondering why part bill what it is when they could of got it off eBay or Amazon for 3rd of the cost lol . Lot of the cheap parts are trash straight out the box and either don't fit, fit/function poorly or pretty much failed in 12 to 18 months ... Buy wisely and refurbish original parts when possible .

Is a few slight variations in subframes depending on exact months built and regional market specific models but general rule of thumb if part off same region and same year it will fit, when those factors vary you may get issue or few to make it fit but most of the time biggest part of it still be same ...

Poor quality aftermarket part perhaps ! From experience I prefer a good used original joint re-greased and new rubber boot over current garbage aftermarket .

Sometimes it the wiring broken at transition flex point to the boot lid . Can't beat the old mechanical handle, mine 25 years old and works same as when come out of factory . The sensor switch boot releases are complete garbage, nothing but hassle and expense, lot of models get water ingress into the switch board (big problems on multi function module/boards that canbus integrated). On some model cars where this incorporates into reverse camera & perhaps even rear wiper all in one the problems caused and cost to resolve gets silly. when linked into canbus networks can completely disable the vehicle and it needs flatbed recovery. Very rare I get to do a diag/repair bill under £300 for resolving this electronic garbage faults, 400 to £800 don't go far sorting this p155 poor engineering concept & low cost component choice of the vehicle manufacturers . No make regardless of prestige/price are exempt from this ... Basically the newer you go the worse it getting in terms of reliability and cost to repair faults . New cars environmental benefits would seem be none judging by the parts bins and service chemical consumption increase I getting . Since Hybrids I do battery recycling by the pallet monthly through winter, pretty much 3 times the battery waste I got pre Hybrid . Cleaner numbers out tailpipe but everywhere else it much worse !

unfortunately problem is bigger than just quality of oem battery. Yes batteries quality is garbage compared to decade or 2 ago but issue that highlights the garbage battery quality is poor electronic engineering (smart charging included in this) and the awful parasitic losses . modern vehicles are nothing but rushed ideas produced at lowest cost with design intent on short life & all the mistakes & constant part failure you can pay for lol .

looks practical and likeable looks. Bit of an old mans car with that wheezy power 😛 Grey imports can be a satisfying purchase, amazing how clean vehicles can be and accurate the auction vehicle reports are from Japan .