Code Fault Location Probable Cause
U0155 Data bus: instrumentation command module - no communication
(Buy Office On Amazon)

We recommend Torque Pro

What Does Code U0155 Hateful?

OBD Ii mistake code U0155 is a generic code that is defined as "Lost Communication With Instrument Console Cluster (IPC) Control Module", and is set when the PCM (Powertrain Command Module) detects a loss of communication between itself and the musical instrument panel cluster command module, or between the instrument panel cluster control module and ane or more other control modules on the CAN (Controller Surface area Network) series bus communication system.

Most modern vehicles have upwardly of 20 microcontrollers or control modules, and many have more, all of which are concerned or involved with controlling, monitoring, or regulating i or more functions that ensure the smooth and efficient operation of all the systems that make modern vehicles work.

Ane such control module is the instrument cluster that conveys vitally of import information virtually the overall condition and efficiency of major operational systems to the commuter. Examples of this data would be the vehicles' speed, temperature, and pressures of diverse fluids like engine oil and coolant, and warning lights that indicate the status of important systems like safety systems, among others.

To integrate all of these systems and their control modules, modernistic vehicles use a complex spider web of harnesses, known every bit the Tin (Controller Area Network) bus system. This arrangement interconnects all the command modules in the application through thousands of circuits to permit systems, subsystems, and a plethora of sensors to communicate both with the PCM and with each other according to strictly maintained communication protocols. All the same, while all control modules transmit and receive information that includes identifying the communicating control modules, the data from and to some control modules are deemed more than important than data to and from other modules.

1 instance of this is information/communication between the PCM and the instrument cluster. If this communication link is cleaved for whatever reason, many other command modules cannot communicate with the PCM(or with each other) via the instrument cluster, which in practice, ways that the PCM cannot oversee and/or monitor the efficient functioning of some critically important control modules.

1 practical instance of this should suffice; since effective control of an automatic transmission depends on (among other factors) the vehicles' road speed, engine speed, and throttle position, the PCM cannot communicate with the transmission command module if the communication link between the PCM and the instrument cluster is broken. In this case, the vehicles' road speed is relayed to the PCM via the instrument cluster, which means that if no communication is possible, the transmission cannot be controlled effectively, if at all.

Thus, if the PCM detects a break in communication betwixt itself and the instrument cluster, information technology will set code U0155, and possibly a warning light as well. Note that depending on where in the Tin can coach system the failure occurred, the PCM might initiate a fail-safe or limp manner- peculiarly if transmission and throttle command is afflicted.

Where is the U0155 sensor located?

The image above shows the instrument cluster panel from a Ford Focus application. Note the black foursquare just to right of center; this is in most cases a CPU (Primal Processing Unit of measurement) that acts every bit a sort of "immigration business firm" for all the signals from command modules that enter and leave the instrument cluster via the CAN bus system.

Also note that while instrument clusters are sometimes repairable by suitably qualified persons, the repaired musical instrument cluster and the PCM almost ever needs to be reprogrammed with the manufacturer's anti-theft protocols at the same time. This is especially true of Ford applications, which may not beginning if the right reprogramming procedures are not followed.

What are the common causes of code U0155?

Some common causes of code U0155 could include the following-

  • Open up circuit in the Tin motorcoach positive circuit
  • Open up excursion in the Tin bus negative excursion
  • Brusk circuit in either or both Tin omnibus circuits
  • One or more failed or failing control modules other than the PCM
  • Failed or failing PCM, but note that while this is not altogether impossible where UXXXX codes are concerned, it is nevertheless an exceedingly rare occurrence