The 2 attached documents I have got from JMC are leaked internal Yamaha UK memos to all dealerships and service workshops.

They show the range of the faulty ECU's up to frame number related, best thing to do is to check if your frame number falls within this range and if so print these 2 documents and take them to your dealer and they shall have no problem in sorting you out with a new ECU

The quality is not perfect but you can just about make out the frame numbers. Sorry but this was obtained by a mechanic and not officially from Yamaha.

For the benefit of all please note these are the affected frame numbers

XT660R Up to frame no. DM015-007858
XT660X Up to frame no. DM014-006257



And thanks very much to JMC for helping me with this even though now you are on the other side of the world, its great that you kept these things safe.

When you say faulty do you mean-cutting out because i think that my XT-R is in that range(it is 2005.) and it's not cutting out

Dear g-tec, the XT660X & R were put on the market in mid to late 2004, as you can see from the attached fax, the first batch of bikes came with a faulty ECU that fault was in the fuelling setting, most of these bikes had serious cut out issues at low rpm, hence Yamaha recognized the problem and offered a free ECU replacement to all owners. Supposedly all bikes built after 2005 should come with the new ECU, however we have heard stories of bikes built after '05 with the same problems which is why I have decided to post this message for owners.

The old saying: "if it ain't broke don't change it" means you are one of the lucky few so don't worry. or..... perhaps your bike was within the range and if you have bought it 2nd hand someone has already changed it or... Yamaha replaced it from the dealership before selling it to you. Open the right hand side panel under the seat that covers the air box and read the number on the ECU to see if its the new or old one.

I am first owner,bought it in july last year,i will check that number Thanks for fast reply

I didn't saw nothing on right side,i think that you ment left side because there is something that looks like ecu if i am not wrong

depends on your definiton of left and right in relation to the bike lets simplify this by saying look on the gear lever pedal side of the bike as opposed to the brake pedal side, i.e. the side where your chain and sprockets are.

Thanks for fast reply,as far as i see those numbers(very hard) mi ecu has other numbers,it looks that i am lucky one

Anyone who can read the frame numbers and the ECU number? And post them?
I think I have a bike with lower number... but it's so hard to read...
Thanks

XT660R Up to frame no. DM015-007858
XT660X Up to frame no. DM014-006257

There is no specification for ECU number in these pages, all you have to ensure is that your frame number is higher than the two numbers above. If not, contact your dealer.

Does anyone know how to tell the difference between the old ecu and the new one?I have a 05 xtx purchased new,my frame number is on the lower side which means I should have the old ecu,but I haven't had any of the problems associated with it! I am wondering did the dealer change the ecu before I took delivery.

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