Micra 1.0L Immobiliser Query

strong electric/mahnetic fields can mess up immobilisers on anything, which is why I don't put my phone in the same pocket as keys. On yours you can re-program the keys for yourself if it happens again. which type of system have you got? separate key fob or buttons in the key?

Thanks for your reply The only keys i have black NATS ones with a red chip in them as its the pikey version of the car. He recoded it using a plug in coding device and also said Nissan would have charged a packet to do the same thing. It only cost me 60 Quid to have them reset . Could a microwave cause the keys to screw up ????

Cured the same thing on our lasses Micra by charging the battery fully ... ;)

CTEK make great chargers, brings dead ones back to life!

Do you think replacing the battery would have caused the immobiliser fault to start with ?

Probably not ... but it could be that the new battery might have been 'on the shelf' for a while and not been up to full capacity. Throw in a few short journeys with little to no charge being added (certainly in my wifes case) and the battery is draining rather than charging.

Worth trying a full charge anyway, the least it will do is confirm the battery is OK or not.

Might also be worth checking the earth lead. Could be that it's been disturbed during the battery changeover.

Ill look at the battery voltage and give it a good charge over the weekend but am a bit worried about disconnecting the battery again in case the immob kicks in . Does this sound like the immobiliser unit is a bit ropey ???

Unless you're going to charge it with a really big charger then don't disconnect it.

=A0

Thanks for your advice much appreciated. Im still not 100 convinced the immob is ok but i will have to wait and see

As I understand it, the memory in the key is non-volatile, it's just an RFID chip. It is the car that has to be taught to recognise and accept the key as being the right key. If your old key still works I think you can forget any microwave/mobile phone damage to your key.

I would have thought though that the immobiliser system in the car would also have non-volatile memory as otherwise every Nissan owner in the country would have to be getting their systems reprogrammed every time they had a flat battery so I'm not convinced that the battery is at fault either. You didn't have a problem when the battery was changed which would support the "non-volatile" memory theory.

This doesn't help you alas. It's possible I suppose that the immobiliser's memory might not be entirely non-volatile, i.e., it might lose its memory if it loses power for a long time. I suppose this could occur if the immobilser's power supply or earth was faulty.

Lastly, RF interference can sometimes cause a temporary loss of function (although not usually wipe an immobiliser system's memory). Got any neighbours with new aerials (CB) or a taxi driver living next door?

Tim

Wife's Micra had a very similar sounding problem. Sometimes had problem starting but after leaving it for a minute or so would eventually start and run fine.

Slowly got worse but would start eventually. Then after a year or so it started cutting out on the road. Felt like fuel running out, so I blamed the fuel pump but tests showed that this was fine. Changed the fuel filter - no change. Next to get the blame was the temperature sensor because after unplugging this and plugging it back in it started behaving. I changed the connector and all was fine for a few months until the problem came back worse than ever. Unfortunately, each time it was taken to the garage it performed fine and there were never any fault codes on several checks. Main dealer was stumped and was suggesting a new ECU for around a grand!

Independent mechanic was also stumped but suggested the crank sensor on the grounds that unplugging it gave the same symptoms. Changed the crank sensor and all was ok again for about 9 months. Back came the problem. Started looking around the internet for a replacement ECU. Found one on eBay were the owner said main dealer insisted it was the problem so he changed it only to have the problem return. He traced the problem to a relay and was therefore selling his working ECU. I emailed him and asked which relay. He very kindly told me.

Pulled said relay from Wife's car and tested it in my lab at work. I discovered that every now and then on operating the relay the contacts, whilst clicking and closing (ie it appeared to be working) showed a resistance of a few hundred ohms. Found the problem!!

This relay is in the relay box beside the battery. It is the immobiliser relay which supplies the injectors. There are two blue relays near the front of the box. One is the immobiliser the other is the radiator fan control. I cannot remember which is which. I swapped them over and ordered a new relay. In the meantime the car would now start instantly on turning the key. New relay arrived and I fitted it and have not had a single problem since. It was autumn and the car was used as a run around so I wasn't too worried about overheating with the dodgy relay contolling the fan for a couple of days until the new one arrived, just kept an eye on the temperature guage but didn't have a problem.

This was more than a year ago so I am convinced that it is now fixed.

Definitely worth checking this relay especially if there are no fault codes to read.

Bill

As another poster said, it's not the keys getting messed up; it's the car that forgets. My Primera also had central locking, which had a separate blipper which the car ignored on a few occasions. It never forgot the ignition code though. For the CL there is a simple sequence involving the ignition key, door switch and fob - no tools or plug in computery stuff required. Maybe the key is similar.

I got the magic spell for the CL from alt.autos.nissan; perhaps the ignition sequence is also known.