As for my E230, 1996 model I had a problem with the alarm. I locked the car using the fob key. but failed to unlock it. what i did was to open using the passenger's seat with a key. Then I removed the positive terminal from the battery. Switched on the engine put back the terminal, out again and back and the alarm was reset. The annoying thing is when I opened the door the alarm went off but at least I was able to drive away smiling....

Yes you need to have a dealer test the system for fault codes.

Check to see if your vehicle honks when you press the "lock" button on your key fob. Press the "lock" button multiple times in a row. Many devices won't beep unless you double-tap the button after locking. If the horn doesn't honk, but the lights flash, your chirp feature is probably disabled.

Use your keyless fob and ignition key to enable the audible chirp. The process varies considerably on different makes and models. You must usually consult your owner's manual, a dealership or the alarm manufacturer for the correct process.

If you lock the car with the key, you must open it with the key, or alarm will sound. If you lock on fob you must open on fob. If you use ke y, place in ignition quickly to silent alarm. Good luck

You will needs to think of it this way. Once you set your alarm it is looking for the corresponding signal to disable itself. That comes from the fob. If you don't use the fob and just use the key, the alarm system is doing its job and alerting you since it has not received the disable command from the fob. Either lock the door with the button when you exit the car if you want to use the key or use the alarm fob. This will also happen if you use the car manufacturers fob to unlock the car if you have locked it with the alarm manufacturers fob.

Hope that helps - I have hidden all of my original car fobs to help alleviate this problem!

Click here to see key fobs.

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.

Not a solution just another problem...Lost my car fob key, have a replacement key no circuit. As I open door, sets off immobiliser like above for20 mins. I had someone look under the glove compartment but that got me no joy. How can I (non techy) resolve this so I can drive my baby home...Vreg Avensis1.8 model?
many thanks

Some Jeep models have the ability to reset the alarm by following this procedure. Connect the battery cables and allow the antitheft alarm to trigger (usually horn honking and lights flashing). Use your ignition key to lock, unlock, lock and unlock the passenger front door. This should reset the system to be used normally. If your key fob is the problem, remove batteries to stop alarm trigger and have dealership test and/or replace fob. Hope this helps.

If this is a factory alarm try using the the key in the door lock and turning the door lock manually. I have seen this issue in chrysler models as well. If this does not work try replacing the batteries in the key fob as this will cause falfunctions as well.