U0155: lost instrument-cluster communication. Distinguish a blank display from an offline IPC and verify software applicability.
Meaning, symptoms, causes and checks
U0155 reports missing instrument-cluster (IPC) messages. A blank display and an IPC that is offline are different findings: establish which is present before replacing the cluster. GM documents software-related examples on listed vehicles; that does not make a software update the answer for every U0155.
Affected system: Control-module communication
Symptoms
- Blank or intermittent instruments, missing readings or dashboard warnings.
- On applicable GM vehicles, the display can recover after an ignition cycle while other modules retain U0155.
Possible causes
- IPC supply/ground or network connector faults.
- For vehicles covered by GM 21-NA-054, a software anomaly is documented; confirm exact applicability and the latest service information.
What to check
- Save codes from all modules and record whether the display is blank while the IPC still responds to the scanner.
- If IPC is offline, verify its fuses, supplies, grounds and network branch before considering display hardware.
- If it communicates but the display fails, read IPC-specific faults and investigate the display/software path instead of treating it as a proven CAN outage.
- Check VIN, equipment and service-bulletin applicability before any software procedure. A workshop must confirm current calibration and the required programming/setup sequence.
- After the confirmed repair, verify communication, warnings and essential instrument readings. Do not continue driving without reliable safety-critical dashboard information.
Also written as: U0155-00, U015500, UO155 (some scan tools add the fault-type byte, e.g. -00).