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Key Fob has stopped working!


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Hi all, 

I took my Impreza WRX (05 plate) for its MOT yesterday but, during the test, the key fob completely stopped working and I had to rely on the Sigma passcode to get the car started. Originally, I thought it was just the Battery so replaced this with a new one.....still nothing. I had a read of the forums and took the key to a local auto locksmith to check the signal from the fob. Apparently this was fine but the immobiliser still doesn't recognise the fob. Tried to re-register the key using the passcode but this hasn't worked either. I also tried to re-register an old spare fob but this didn't work either.

In desperation I contacted a local auto locksmith in North Somerset who supposedly 'specialised in Subaru' but he was a lost cause! So, I have 2 keys, neither of which are recognised by the immobiliser/alarm and I am currently reliant on entering the keycode every time to start the car. 

Any advice, guidance or support to help rectify this is greatly appreciated!!



Gareth aka Coffinhammer


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That the Sigma M30 alarm system.
One would guess if 2 fobs not working then alarms receiver module got issues .
Have you tried disconnecting vehicle Battery for few minutes and retrying (including reprogramming fobs)
A cheap and technically easy solution to faulty alarm system modules is buying a used complete M30 alarm (must be supplied with at least 1 working fob and/or pin code) & fitting main module/suspected faulty parts & programming fobs (you get extra fob which can be handy and board/casing could be used in one of your keys if needed .
We done this method on at least 3 subarus in last year that I can recall & used parts cost was in the range of 80 to 120 quid & we had modules fitted, new 9v Battery replacement to siren, new fob batteries and programmed in under 2 hours .

Removal or bypassing the M30 is also not that hard but ideally you likely need some alarm/security for insurance purposes !

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Cheers Mr. B. I did try disconnecting/reconnecting the vehicle Battery but without success. 

This morning, though, it got worse. Got in it to go to work, typed the PIN in the keypad and the alarm went off and would not reset with the PIN code. Ended up disconnecting the vehicle Battery and being very late for work! The car is now dead until I can find someone to come and look at it and, hopefully, remedy it. Sadly, I think I might need a new alarm system.

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It could be Just the Siren faulty (does the pin code allow car start even if siren barking), Siren has a 9v rechargeable Battery in it that zip tied  to the control board, Battery leaks and board corrodes & siren does all sorts of odd things (come across this all the time due to age of them now) .
not seen siren cause issue with fobs not working but you never know with electronics mixed with  water/corrosion lol
The siren is under scuttle panel, is easy open (2 screws down sides of slots for mounting bracket square nuts . you can disconnect siren wiring right at plugs on circuit board .
New alarm not a big deal but is super cheap and quick swap out used parts of another working M30 and maintain original all in one keyfob ...

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Sadly the car will not start at all, whether the alarm is sounding or not. Leads me to the conclusion that the immobiliser is likely to be the problem. I've had a chat with an auto-electrician via a mate, and he's going to come and have a look tomorrow. Also looking into a replacement M30 as per your recommendation.

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Main M30 module easy replace and worth servicing siren with a new 9V rechargeable Battery if do repair current M30 setup.
You can get whole used M30 system pulled from a subaru cheap on eBay or a local breaker .
If it just the main control module you can find them for around 50quid range (just be sure get a key or code with it for easy programming)  .

Hopefully all works out good and you up and running before xmas ...


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