I've had a recent problem with my immobilzer. With the key in the ignition the immobilzer was not clearing and the car would not start. Honda have recoded the keys for free and the problem is fixed. Does anyone have any ideas what would cause the keys to malfuction?

I was wondering if exposure to a MIG or TIG welder might do it. I was welding for several hours with the key in my pocket.

 

The immobilizer uses a little RFID tag in the key. Certainly welding creates strong electromagnetic fields, but I never heard of that damaging the keys.

I wonder whether our FCC vs. your UK ministry of whoever regulates radio transmissions, might require the systems to be different over there...?

 

Thank you Jim

I check out the question of arc welding damaging the key - as you say it should not be a problem.

I find auto electrics confusing.

 

Yeah, & the immobilizer is even stranger than the "normal" auto electrical system. It's a little ring antenna that fits around the ignition key cylinder, #14 in the picture (USA car). But unless you were welding inside the car, that stuff wouldn't be suspect. Coincidence?? Look for loose connections to that thing.



The RFID chip receives a tiny amount of electric power from that antenna, just enough to transmit back it's serial # so the ECU can decide whether it's an authorized key. So I can sorta understand a welding arc might overpower that little chip in the key.

But if so, why aren't there more stories about this happening?? There's a gazillion cars with immobilizers, any you can't possibly be the first guy to do any welding with a car key in your pocket.

 

I think you are right, there would be lots more cases reported if arc welding damaged the key. Well Honda couldn't explain it but they did recode 2 keys for free and said the third key was faulty and could not be recoded.