If your diagnostic scanner has reported fault code U1900, don't rush into replacing expensive control modules. In many cases the fault is caused by a wiring issue, poor power supply, low battery voltage or a communication problem elsewhere on the CAN Bus network. At C.A.R.S., we specialise in finding the actual cause before recommending any repairs.

U1900 CAN Communication Fault Repair
s Your Vehicle Showing Fault Code U1900?
We Diagnose and Repair U1900 CAN Bus Communication Faults
If you've scanned your vehicle and found U1900, don't panic.
This fault code doesn't always mean a control module has failed. In many cases, U1900 indicates that one or more modules on the vehicle's CAN Bus network have stopped communicating correctly. This can be caused by wiring faults, poor power or earth connections, low battery voltage or a faulty module on the network.
At C.A.R.S., we specialise in diagnosing electrical communication faults rather than simply replacing expensive parts.

Common Symptoms
You may experience one or more of the following:
✔ Vehicle won't start
✔ Intermittent non-start
✔ Multiple warning lights illuminated
✔ Dashboard displaying numerous fault messages
✔ Instrument cluster not working correctly
✔ No communication with one or more control modules
✔ Central locking or electric windows not operating correctly
✔ Steering or ABS warning lights
✔ Battery drain

What Does U1900 Mean?
The U1900 Diagnostic Trouble Code relates to a communication problem on the vehicle's CAN (Controller Area Network) Bus.
Modern vehicles contain many electronic control modules including:
  • Engine ECU
  • Body Control Module (BCM)
  • Instrument Cluster
  • ABS Module
  • Airbag Module
  • Steering Module
  • Immobiliser
These modules constantly exchange information. If one module stops communicating, the diagnostic system may store a U1900 fault code. On some vehicles, especially Ford models, U1900 can also appear during diagnostics without indicating the root cause, so further testing is essential rather than replacing parts based on this code alone.

Common Causes
We regularly find faults caused by:
✔ Damaged wiring
✔ Corroded connectors
✔ Water damaged modules
✔ Low battery voltage
✔ Poor earth connections
✔ Blown fuses
✔ Faulty Body Control Modules
✔ Instrument Cluster failures
✔ CAN Bus wiring faults

Don't Guess – Diagnose
Many garages immediately recommend replacing expensive control modules.

Unfortunately, this can become very costly if the module isn't actually faulty.
Our approach is different.
We carry out professional electrical diagnostics to identify the actual cause before recommending any repairs.
This often saves customers hundreds of pounds in unnecessary parts.

Why Choose C.A.R.S.?
✔ Established since 1990
✔ Mobile Auto Electrical Specialists
✔ Advanced diagnostic equipment
✔ Specialist wiring fault diagnosis
✔ Honest advice
✔ Lifetime workmanship warranty
✔ No VAT
✔ Mobile service at your home or workplace

We Can Repair
  • CAN Bus wiring faults
  • Body Control Modules (BCM)
  • Instrument Clusters
  • Electrical wiring repairs
  • Water damaged wiring
  • Communication faults
  • Module programming
  • Network diagnostics

Frequently Asked Questions

Can I still drive with a U1900 fault?
Sometimes yes, but many vehicles will experience starting issues, warning lights or loss of certain electrical functions. It depends on which module has stopped communicating.
Does U1900 mean my ECU is faulty?
No. U1900 is a communication fault, not a diagnosis of a failed ECU. Wiring, power supplies, earths or another module on the network may be responsible.
Do you offer a mobile service?
Yes. We can carry out many diagnostic and repair procedures at your home or workplace.

Call C.A.R.S.
If your vehicle has stored a U1900 CAN Communication Fault, don't replace expensive modules until the fault has been properly diagnosed.
📞 Call Ursula on 07970 252155
We'll be happy to discuss the symptoms and advise on the most appropriate next step.