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Key Fobs Both Stopped Working

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Does anyone know why both keyfobs would stop working?

This happened this evening. i went to the car pressed the boot button and it opened.

I went out about 30 mins later and tried to open the car and it would not. I used the fob but nothing. I thought the Battery may be low (14 months old) so got the spare. That wouldn't open either.

I popped the lock cover and opened the car with the key. the alarm activated but the fobs still wouldn't work.

I left the car locked outside.

I can ring Lexus tomorrow but would like to find out sooner.



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Happens every now and again. Radio interference from routers, microwave ovens (usually from the control circuitry, not the magnetron so don't panic) or anything that generates a radio signal can potentially interfere.

It could be a one off due to any number of factors.

If it happens often where you park, Lexus can change frequency which may solve your problem, it just depends what and how the signal is being blocked/distorted.

I know a couple of spots that I cannot go to as the key simply will not work, even with it touching the start button.

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It's in the same spot where i have always parked it.

How do I get it working again? Just tried it again and still will not open.

I don't want to wake the neighbours at 23:58 by setting off the alarm again so will wait till morning.

I have done a WIFI scan and there is my router (Draytek) and a Linksys none with any strong signal.

Does anyone know what procedure to follow in getting it to start?



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Sometimes holding the keyfob actually on the start button will do it.

Can you get another vehicle around/close to yours? You can possibly block the signal. (The RAC and AA have had success with this)

Have you been everywhere around the vehicle so different sensors will possibly pick up the keyfob?

As stupid as this may seem, give it a try with a homemade waveguide like a metal collinder or pan or something pointing at the car and the keyfob in the centre. Go around the car. I realise you will look a bit of a dope though and probably think I'm winding you up!! :lol:

I appreciate you can't roll it a few yards and try again this time of night but that's the first thing to try in the morning.

There's someone else who can't park on his drive on here... can't think of who. Just stopped working one day in that spot. I think he was going to get Lexus to change the frequency.

There is a possibility of course that there is a fault with the system, but more likely it is this.

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Well, this morning i tried again.

The remote still wouldn't work so i popped the cover off the door lock and turned the key and the alarm activated.

I tried to start the car by pressing the button with the remote but it said "No key detected". Tried 3 times and then the alarm stopped and then pressing the button with the fob worked. I moved the car to the drive and the remote started working!

Spoke to Lexus and after me insisting the both remotes were not flat batteries, they agreed to swap out the remotes and reprogram to a new frequency.

As I am taking it in in 2 weeks for a service, I agreed to do it then.

I have searched for wifi points around the car and found 3. I have changed my frequency from 11 to 1 and still no joy. My car has been parked in the same place every night for the last 14 months but this is the first time. Maybe someone has just fitted some device near me.

The person at Lexus Manchester advised that there are some well known sites (trafford Centre is one of them I was told), that caused this type of fault.

Lets see what happens.

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by their very action of recognizing the Trafford Centre is well known for a similar problem,

Lexus are admitting an issue they should be finding a solution to.......

It might not be a Lexus problem... Some areas (especially very populated areas e.g. the Trafford Centre) have devices to purposely jam certain radio frequencies so they can't be used for let's say, bomb detonators. Not saying this is the case, but I know these areas exist in Europe...

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  • 1 month later...

Just sweeped my street and for bomb detonators and the good news is we are all clear :whistling:

I live in a field in Standish and there is one other neighbour with a WIFI network (other than me). I have even changed my channel and even turned it off but it stil had would not work for that evening.

I have had my broadband for 5 years with 6 differnet routers (because I work in IT and buy all kinds of routers for support testing).

So... I am not sold on this idea. I need to find out the actual frequencies and not just bollocks about bomb detonators! (sorry!)

But I always look for a simple problem than NORAD or MI5 targeting a 2 square meter area of my road!

Since Lexus reprogrammed my fobs and car, the bad guys have gone home... :shutit:

Simple... IT IS A BUG!! Get over it!

Have a great new year.

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There are several issues here and not all the blame can be placed on the manufacturer.

They don't just transmit a single code, the fobs send the same code many, many times in a few milliseconds. They must all match, undergo identification, mitigation and the discrimination of real transient signals from the spurious ones. If there are disturbances among the receive sequence and say only an 80% successful packet transmission is received then the security system won't respond to it.

Anything within the communication edge of the transmitter can cause the undesired effect. Simple things like wireless doorbells, antenna boosters (TV, cell or military), wireless routers, video senders and all sorts of things your neighbour may have or someone around you. Its not always as simple as someone close to you either due to more complex things like Faraday scatter effects, artificial waveguides, etc.

Car alarm, immobiliser and central-locking systems are permitted to operate license-free at 433.72-434.12 throughout Europe. Some older radio keyfobs in the UK operate around 418MHz. Assuming that these transmitters do not emit excessive out-of-band noise (whether harmonics or spurious), the problem lies with the adjacent channel performance of keyfob receivers. Changing frequency works a lot of the time because of this.

All car manufacturers suffer from this issue to some degree. Its certainly not a Lexus only issue.

The same frequencies are already legally allocated to other users - the primary UK user being the Ministry of Defence, with secondary users including amateur radio operators and traffic information systems. The answer really would be to change frequency range which would help but car manufacturers in the UK haven't really commented apart from Jeep who claim it's not possible because of government restrictions.

It may even be that super-regenerative receivers are used instead of the more selective superheterodyne type. Super-regenerative receivers tend to have very poor adjacent channel rejection.

The UK Government set up the Radio Activated Key Entry (RAKE) committee, which has recommended that radio keys for vehicle access should only be treated as a convenience feature and should never be used as the sole means of activation in safety critical situation.

Either that or the batteries are low like Dave's. Or Aliens.

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@ Geoffers - you know way too much mate :P

The UK Government set up the Radio Activated Key Entry (RAKE) committee

Is that like the Bureau for Unlocking Mechanisms For the United Nations (BUMFUN) committee?

Guess like you say there is a lot of noise out there on all the spectrums now!

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