Hi,
2000 Elantra hatchback with factory immobiliser, transponder in key, located in Sydney/Aust.

symptom ; starts AOK, then soon as starts, dies immediately. Not even enough time to rev it, just starts and dies immediately.
Key to "off" then try restart.
Often will not fire, but occasionally will repeat the start-then-die-immediately scenario.

Can resolve problem with removing key from ignition, then arm and disarm the remote and try starting again - usually goes AOK.

Have new Genuine key, coded by Hyundai dealer, yet to properly "test" if symptoms persist with this new key.

My thoughts are the transponder in the old key is dead, and hence not turning off the immobiliser.

But is there any way of checking the immobiliser circuit - presumably there is some sort of "reader" near the ignition to pick up the presence of the key's transponder???

Any thoughts on the functioning of the immob system, or even other thoughts on likely culprits are greatly appreciated.

Cheers, David B.

Maybe it's not the immob. Have your car's comp checked at the service. Hope it's only sensor fault.

Hi,
thx for the thoughts,

I never found out a way to "test" the functioning of the immobiliser circuit, specifically the key transponder sensor which sits around the ignition barrel...

I was thinking of attaching some sort of data logger to the key sensor outputs, but it got terribly complex, terribly fast.

I opted for disconnecting above terminals, cleaning, tightening the slip-on connectors and then re-attaching. That was about 1 month ago and it hasn't faulted since. Touch wood.

If the fault re-appears I will investigate either data collection, or simply try replace sensor with one from a wreckers.

Hope this helps any other readers with similar probs,
Cheers, David