Put alarm on with the key fob, all doors lock and red light flashing after about a min sounds like doors unlock, but don't if left like it alarm goes off did this twice use key to lock its 02 s40.

To arm content theft alarm.
1. Open the door.
2. Lock the door with the power door lock switch or
the remote keyless entry transmitter. The
SECURITY light should flash.
3. Close all doors. The SECURITY light should go off
after approximately 30 seconds. The alarm is not
armed until the SECURITY light goes off.

If a locked door is opened without the key or the remote keyless entry transmitter, the alarm will go off. The headlamps and parking lamps will flash for two minutes, and the horn will sound for 30 seconds, then will turn off to save the battery power.

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CODE ALARM SYSTEM
information is always subject to change and correction Used on:
Impreza 1996-2001
Legacy 1995-1999
Forester 1998-2000
Battery GP-23A
Lock: Left button will lock all doors. Double chirp indicates locked.
Unlock: Right button will unlock driver's door only. Hold unlock button app 6 seconds, it will unlock all doors including rear gate. Single chirp indicated unlock.
If the car chirps or lights flash 4x the alarm was triggered.
Panic. Press both buttons to activate emergency honk and flashing lights.
Valet mode: With optional alarm only Press the red alarm button on the left of the steering wheel. The light will quickly double flash. To re-set back to normal mode, press the red alarm light button again

Battery failed and lights flashing?
Parking lights will flash when the vehicle's battery is disconnected and reconnected.
To stop lights from flashing, either:
Press remote transmitter “UNLOCK” button once OR turn the ignition switch to the “ON” position and press programming button for one second (see below).
The vehicle interior (courtesy) light and door open warning light (DOOR AJAR indicator) will then illuminate for 60 seconds when the ignition is turned off, or until the doors are locked with the remote transmitter. Yes, the dashboard instrument panel lights will flash when the parking lights flash.
Programming or Overriding the Alarm when you have lost the remote
Open driver's door.
Turn ignition key to 'On'
Press and *hold programming button* in (see diagram, button under dashboard)
After 15 seconds the the door locks will cycle 3 times. Do not release Programming button
Press lock (left) button the remotes to be programmed. The door locks will cycle one time.
Exit programming mode by releasing Programming button under dashboard and turning key to off.

Code Alarm Programming Button is under dashboard on the kick panel by the driver's left knee, left of the steering column. If you can't find it, it might still be tucked up in the wiring harness higher up in that same general area. The botton is recessed in a plastic ring (see diagram).
This button must be pressed while programming remotes or if the battery was disconnected and the lights are flashing.
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It's your built in security alarm , have you changed the battery lately ? The procedure to reset it is: Unlock drivers door with key, then use key fob in unlock door mode, put key in ignition switch, foot on brake , transmission in park or neutral and clutch depressed (If applicable )

Sounds like the key fob is going bad and needs replaced.

If you have an after market alarm sys. take it back to who ever installed it . as far as the key & lock sys . spray some WD40 into the lock and try again . disconect the alarm speaker until you figure it out . Good Luck

You should be able to just unlock the door with the key, and even if the alarm is still going of try to start it the key should override the alarm.

you may have a bad door switch, theres a switch on the drivers door lock, when door is unlocked with fob or key the switch is activeated to shut alarm down,the lock moves to hit switch with key or fob,so if the switch is bad it will not shut down alarm, i would start there,door panel has to be remove,then latch has to be remove to get to switch, then test with a meter see if it opens and closes the connection, hope this helps.

Sounds like you have an aftermarket alarm with starter disable. By disconnecting the battery the alarm reset and the defualt setting is usually to set the alarm automatically (active arming). You have three options..
A. If you have the key fob that went with the alarm you can disarm the alarm.
B. If no key fob is available you can disconnect the battery again, turn the ignition key to the on position and reconnect the battery. This usually doesn't allow the alarm to set and allows the car to start.
C. Remove the aftermarket alarm system. This is usually the long term fix i recommend if the fob isn't available. Option B should get you going though.

Do you have a key fob? Unlock the car with that and you should be OK. My sons Elantra is the same way, you can only get in with the fob. I guess the car thinks it's being stolen otherwise. If you don't have a fob, I'm no help

The ignition security on/off is located at the trunk lock. unlock and lock rear gate and the alarm will turn off. My jeep sat in my drive for a month before a jeep tech told me this. It still triggers the security sometimes when I unlock the passenger door with the key and I go straight to the rear gate lock and it shuts off instantly.