OBDII DTC U1900 Fault on Ford Focus 2. How to fix

Errors diagnosed by mobile scanners and computers in one way or another indicate a malfunction in the engine management system. And these errors are not always duplicated by the Check Engine icon. In the case of the common error u1900 check lights up very rarely and most owners of Ford Focus 2 are surprised to find this OBDII code only when scanning.

U1900 code, causes of error on Ford Focus 2

No one probably needs to be told that all the electronic modules, sensors and systems of the Focus mk2 communicate with each other using a specific protocol. A high-speed system of data exchange between modules and nodes is provided by CAN buses. Any malfunction or loss of data by the system is immediately displayed in the form of a Check Engine message and duplicated in the ECU memory as an error code.

These faults can then be read by a scanner or diagnostic computer. There is a certain list of the errors that relate to the information exchange system between the modules, here it is in condenced form:

As you can see, any of these faults can cause a lot of trouble if they are not corrected in time.

How the U1900 failure appears in Focus

The difficulty is that this code may not be active for a long time, but at a certain moment it will shoot out, leading to the failure of electronics in one way or another. We are well aware that any device and any system can be disabled if the information flow fails (and which one, the scanner does not specify). In the best case, it will be the connector of the scanner, which reads errors, in the worst case – alarm system, power system, catalytic converter, in a word, anything.

Of the obvious symptoms that can’t be overlooked, such abnormalities can occur:

Since all the Focus Mk2 have already passed the warranty mileage, you will have to eliminate the error U1900 by your own hands or pay the dealer center. We can always get there in time. As a rule, the dealer, like a bad polyclinic, will find a whole heap of other faults in our Ford. But there is no guarantee that the error U1900 will be reset. Therefore, in order not to pay too much, let’s try to solve the problem ourselves.

Diagnostics, fault reset and removal of the consequences of U1900

In principle, it is possible to do not quite right and just erase the mistake from your memory. Out of sight, out of mind. This can be done elementary with the same scanner ELM 327 even on the fly. But this will not solve the problem. The only effective method is a thorough inspection of all CAN bus pins and probable soldering of the board.

In 90% of the trouble lies in the contacts that are on the dashboard board. To get to them, you need to disassemble it completely and free the board for soldering. Removing the dashboard on the second Focus is not difficult. To do this, simply lower the steering column, remove the plastic pads, unscrew the two screws and remove the dashboard, pre-disconnect the terminal block.

After disassembling the dashboard and carefully removing the arrows, we get access to the circuit board, which must be soldered in the place that we indicated in the photo above. For soldering it is necessary to use either a soldering station or a low-power soldering iron not more than 20-25W.

In principle, the most serious errors that can affect the operation of the engine are duplicated by the Check Engine warning light and disassemble the dashboard for the sake of soldering and resetting CAN Communication Bus Fault does not always make sense. At least we know what error code U1900 means and what to do to fix it.