"key Not Detected"

[Bill Badger]

I'm getting a constant warning on my Mondeo Titanium that the key battery is low. I've changed the battery for a new, good quality replacement but the warning symbol returned within a day or two. I've put up with it for a few weeks because I know the battery is new, but I'm occasionally getting a 'Key not detected' warning, which is rather worrying because the car won't start.....! It seems to sort itself out after ten seconds or so, but it's obviously a bit worrying because one day it won't!

I recall hearing about one or two problems from others. Anyone had similar issues?

[ppeter7]

is it the sensor ring on ignition at fault ive had this on a work van

[Italiot]

I get the same problem on titainum x about every six month I change the battery and it last for another six months but no one has managed to find a resolve for myself be interesting now they've been out a while if now resolve

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[kristriple]

This happens occasionally on my 2007. Depends how old your car is I suppose? I just ignore mine and try again in a few seconds.

[alexp999]

Do you have the keys in a pocket or bag near a mobile phone?

They can cause interference with the transmitter.

[The Admiral]

I had that a few weeks ago for the first time?, I just started using the other fob, But out of interest how long do they last? and can anyone change them?

[higgsy]

My focus keys are very sensitive to the batteries, I got some Maxell batteries and was getting through them at the rate of one per 2 weeks. Key not detected, key not unlocking car sometimes, remote battery low. I put an enegizer in about 2-3 months ago and no issues whatsoever since.

[The Admiral]

Hi Higgsy that seems a lot !, I've had my car almost 2 years and I've never replaced any batteries, Am on my 7th Mondeo since they began in 1993 " K-reg" and I've only ever changed one set in my R reg ST Mondeo I had years ago.

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[higgsy]

What I was getting at was the keyless remotes don't like certain brands of batteries, I had a maxell battery in my old corsa remote for years and didn't ever need to change it, yet when using them in the focus keyless remote they caused issues.

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[Italiot]

I put Duracell battery in my fob and usauly last about 6 months

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[Pete80]

Just changed the battery in my fob as it appeared to be going flat, got a duracell jobby in so will see how long it lasts