Fiat 2.8JTD Starting issue ..keys from two different vehicles on the same bunch ?

[scotjimland]

Can having ignition keys from two different vehicles on the same bunch cause an issue with starting ?

Yesterday the van just cranked over, usually it starts on first turn of the key.. tried a few times , then it started

When out shopping and it did it again.. twice..

Plenty of fuel, but then I wondered, did having my daughters car key on the same bunch cause a problem?

I tried googling this without a definitive answer ..

I have removed her car key and tried starting several times with no problems.. but still unsure if that is the problem..

 

[Figaro]

I think your key speaks to the immobilizer so having a second key present might interfere with that handshake ?
Having a second aftermarket immobilizer might increase the likelihood.
Just my non expert museings

 

[scotjimland]

I think your key speaks to the immobilizer so having a second key present might interfere with that handshake ?
Having a second aftermarket immobilizer might increase the likelihood.
Just my non expert museings

that is also my thinking ..

just been out to try, it started first turn of the key..

 

[scotjimland]

Useful reply from a Fiat forum member ..

You did not state, or perhaps notice whether or not the key code (padlock symbol) light extinguished, but otherwise your description matches that of key code failure.

My answer to the query raised would be yes, quite possible, as the key from the second vehicle could also respond, and cause corruption of the correct code. Also I have read a sensible suggestion the other metallic objects on the key ring may absorb the weak RF signal, with similar results.

 

[scotjimland]

More advice on the Fiat forum basically concurs with the above with some useful info

Fiat Forum

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[Jev88]

Do you have the older Red key and Black keys? Don't use the red key - it enables basic programming of the black keys. Use it every day and it can wear out and can trip the system into learning mode looking for a black key? I'm no expert but can see this being a problem with the older "master keys" system.

 

[scotjimland]

Do you have the older Red key and Black keys? Don't use the red key - it enables basic programming of the black keys. Use it every day and it can wear out and can trip the system into learning mode looking for a black key? I'm no expert but can see this being a problem with the older "master keys" system.

Just the black key came with the van, the dealer had two spare keys made , one of which I was using.. I kept the back key safe... am now going to use the black key, on a fob with no other keys ,

 

[Headrush]

I have keyless entry on my car and I find that the door doesn't unlock if I'm holding my phone in the hand that's opening the door. These NFC systems are designed to be very low power so interference is definitely possible.

 

[pappajohn]

Put her key back on the bunch and try again
If the fault reoccurs then that's the problem.
I suppose one key could be saying "wrong key" and cancelling/over-riding the correct key.

 

[scotjimland]

Fiat Forum reply

My current understanding is that when the ignition is switched on, a radio signal is used to supply power to the key. In effect a non specific challenge, to which any key within the limited range may respond with its code. If the received code matches one stored in the vehicle, the key is recognised. From eLearn, at the same time the ECU sends a code to the code recognition device, which returns the code only if the key has been recognised. If the code is repeated back, then injection of fuel is allowed. This latter code is described as a rolling code, which I assume means that it changes at every start. If two keys are within range, I agree that the second key could corrupt the code transmitted by the first key.

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[Manxcat]

My mobile phone interfered with the key earlier this year. Took me ages to work out it was the phone.