Hello guys for a few months my focus fuel light stays on the gauge does not move, the display read "fuel computer data error" not sure exactly what that means any information would be apreciated.

You should first diagnose the instrument cluster with a suitable diagnostic system. For example an ELM327 interface and the ELMconfig software. The instrument cluster will have stored DTC codes which could point you in the right direction.

Personally I expect this problem to be caused by either a defective fuel tank sender inside the fuel tank or a defective instrument cluster.

Jw1082 thanks very much for that info I will try and do a gauge sweep test but I think I have already tried that not sure what a elm327 is would I have to go to a garage to get that diagnostic done? If it is a defective fuel tank sender will it be expensive to fix?

The gauge test does usually not show all stored DTC codes (usually only a limited number of critical DTC codes). I am afraid this will not give you the codes about this problem.

The instrument cluster can only be diagnosed with a suitable Ford specific diagnostic interface. Most generic diagnostic systems can only diagnose the engine/safety related DTC codes (prescribed by law) and not manufacturer specific DTC codes.

An ELM327 interface is a cheap universal diagnostic interface which can be bought for about €10,- from Ebay. Combined with the free Russian ELMconfig software and a modification to the ELM327 interface you can diagnose and configure practically all (CANbus) modules of the Focus MK2/MK2.5.

The fuel tank sender costs about €125,-. However it is a large amount of work to change the sender. The fuel tank must be removed from the car completely to have access to the tank sender unit assembly. The fuel tank sender is basically just a simple adjustable resistor which is attached to a float. The fuel tank sender can simply be tested by a multimeter. With different amounts of fuel in the tank you should measure different resistances. If the fuel tank sender has a permanent open or closed connection or the measurements are completely out of range it will be defective.

Another possibilty is a defective instrument cluster. The Focus MK2/MK2.5 instrument clusters are known to have problems caused by bad soldering connnections of the circuit board. As a result of vibrations (especially when driving on bad roads) the soldering connection become cracked which causes a bad connection or no connection at all. Depending on which connections are bad this can cause various electric or communication problems.

jw1982 You obviously know your stuff im Gona be honest I had to read that about 3 times to take it all in lol the elm327 seems like a good idea to be able to diagnose the problem but I'm not sure I will understand how to use The equipment but I might just order it on eBay tonight and I'll let you know how I get on, if it is the fuel tank sender unit and the part costs £125 how much would u guess I'd get charger in labour or if it's option b and it's the instrument cluster what do u think the damage would be on that?

To remove/install the fuel tank by a specialist my estimated guess will be about 4 hours. I did this myself a few years ago on my previous Focus MK2 and it took me (as a hobby mechanic) about 6 hours.

Most times the soldering problem of the instrument cluster can be solved by resoldering the soldering connections of the large connector on the circuit board. If you are handy with a soldering iron you can do this yourself. Taking apart the instrument cluster will be the hardest part but if you work slow and precise this should also be no problem.

ok so am I correct in saying that if I purchase a elm327 I will be able to detect weather it is the fuel sender unit or just the gauge cluster? I think electrical and soldering is way out of my depth wish I could do everything my self my focus has a small list of jobs on it

I have just done the sweep test and these Dtc codes came up.

#019202

#029318

#03a103

Not sure if that makes it more clear

The codes I believe are

9202: fuel sender open circuit

9318: battery voltage low

A103: antenna not connected.

Did you find out what the problem was . I have a 2006 the error says . Fule computer fault . And I don't have a clue and it won't start or eaven turn over