CAN network

U0155 — Lost Communication with Instrument Panel Cluster

Severity: medium Drive with care, to a shop

What U0155 means

U0155 means another control module, often the PCM or BCM, stopped receiving messages from the instrument panel cluster over the CAN bus. Normally the modules constantly share data on a two-wire network, and the cluster uses it to show speed, RPM, temperature, and warning lights. When that exchange breaks down, the cluster may behave erratically or go dead.

Symptoms

  • Gauges erratic or not moving
  • Warning lights stuck on or never lighting
  • Blank or flickering cluster display
  • Several warning lights on at once
  • Intermittent no-start
  • Functions of other modules unavailable

Possible causes

  1. Open or shorted CAN bus wiring, chafed harness
  2. Failed instrument cluster
  3. Missing power or ground at the cluster, blown fuse
  4. Corroded connector at the cluster
  5. Low battery voltage or charging problem
  6. Another faulty module loading down the bus
  7. Rarely, a faulty PCM/ECM

How to diagnose

  1. Check battery voltage and charging system output
  2. Scan all modules and note which ones are missing from the network
  3. Check the fuses feeding the instrument cluster
  4. Test power and ground at the cluster connector
  5. Inspect the cluster connector for corrosion or moisture
  6. Measure resistance between CAN-H and CAN-L at the diagnostic connector (about 60 ohms is normal)
  7. Inspect the harness for chafing or breaks and test for shorts to ground or power
  8. Unplug suspect modules one at a time, only following a documented procedure

Common fixes

  • Replace the fuse and restore power and ground to the cluster
  • Clean or replace corroded connectors
  • Repair the CAN bus wiring
  • Replace or repair the instrument cluster and program it as required
  • Replace a faulty module that is disrupting the bus

U0155 on different brands

Ford · manuals
On Ford, U0155:87 means a missing message from the instrument cluster; per SSM 51578 on the 2023 Super Duty it can be a BCM self-test history code rather than a confirmed module failure.

Questions and answers

What does U0155 mean?

A control module lost communication with the instrument panel cluster on the CAN bus. The cause may be wiring, cluster power, or the cluster itself.

Can I drive with U0155?

Only briefly and carefully. The gauges and warning lights may not work, so get it fixed as soon as you can.

What should I check first?

Start with battery voltage and fuses, then power and ground at the cluster, then the CAN wiring and connectors.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.