few year back, my master key unable to start my car.
When I try to attempt 1st start, it will crank the engine but won't startup the car. when u turn off and start again , It won't crank engine unless I had to remove my key and wait for 3 sec and insert back then it will allow me to crank engine, of course it won't start up the car.


However when I use spare key, it will start up the car without fail. So I leave this problem for years until last year, my spare key cannot start the car. I tried many times and when I used back master key, it will start up the car.
So I leave this problem again for year until now


Currently both key unable to start up the car, it can crank the engine, radio and air con can work when key is turn.
Battery changes.
Now the only way to start up my car is using remote control to start.
Which mean battery / startup motor is still ok.
what is the problem?

 

Can you lock/unlock the car with the keys? My first though was maybe the battery is dead. My next thought Would run be something mught be wrong with the chip or imobalzer in the car and you might need the dealer to look at it.

 

Yes, still can lock and unlock car doors

 

It does sound like an immobilizer difficulty. If so, the dashboard light for the immobilizer (a green key-shaped light on mine) should come on and stay on or blink or something like that. At least on my '12 Fit, normal operation is for it to very briefly flash when first starting the car as it reads the chip in the key, and be off otherwise.

If the engine is cranking at the normal speed, your battery would appear to be decent, at least sufficiently so to start the car. If it struggles to crank over, it could possibly be a battery problem—but that wouldn't explain why one key works and the other doesn't.