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karlandrews

u1900

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Hi,

I have a 2010 plate, 1.8 petrol ford focus.
I was driving to work and the engine suddenly the dashboard light up like a christmas tree  went into 'speed limited mode the engine ran fine from work
And when I turn the car off it doesn’t come back on it happened again over the weekend i borrowed a friends obd reader and it come up with fault u1900 

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DTC U1900 = CAN Communication Bus Fault

DTC U1900 is not Always an actual fault. This code can also be caused by the diagnostics itself. This DTC code is quite common. Many vehicles without any problems also show this DTC code during diagnostics.


Because of this DTC U1900 is not a reliable code.I suggest to perform further diagnostics using a Ford specific diagnostic system. A Ford specific diagnostic system can diagnose a lot more (CANbus) modules and shows a lot more (manufacturer specific) DTC codes than a generic diagnostic system. In this case I would look specifically for DTC codes that are stored in the instrument cluster because al symptoms point to the well known instrument cluster problem. 

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5 minutes ago, JW1982 said:

 

DTC U1900 is not Always an actual fault....

 

I reckon, from the OP 1st post, he does have an 'actual fault' LOL

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In 90% of all cases the U1900 DTC code is not related at all to the actual problem. The U1900 DTC code is usually set during diagnostics because the diagnostic equipment causes a very short loss of CANbus communication when accessing the CANbus network. 

In this case the U1900 code itself is just a generic loss of communication code which does not tell anything. Without further information the DTC code itself is basically useless. Much more information is needed to be able to determine whether this code is related to the actual problem at al. For example:

* which module contains this DTC code?

* what suffix did the code have? The suffix of the code usually contains much more information than the code itself. 

* is the code currently active or was the code previously set? Decent diagnostic systems show when the code was set (mileage) and whether the code is currently active or not. 

 

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its done it again today started the engine came up with speed limited turned the car off restarted it everything is fine again and no code showing would i be better booking it in to ford for  diagnostics  

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