The most common causes of U1603 include: CAN bus communication timeout; Control module offline or not responding; Wiring harness damage or short circuit; Software version mismatch between modules. A professional OBD-II scan tool is recommended for accurate diagnosis.

How do I fix U1603 for Chevrolet / GM Lyriq?

Recommended steps to address U1603: (1) Schedule a diagnostic check within the next week (2) Monitor the issue for any changes (3) Check for software updates at your next service visit (4) Document any symptoms for the technician. Always consult a qualified EV technician for high-voltage system repairs.

Is it safe to drive with U1603?

U1603 is a caution-level code. It is generally safe to continue driving short distances, but have it inspected at your next scheduled service visit.

Chevrolet / GM Lyriq

U1603

Caution

Lost Communication with Instrument Panel Cluster

Severity

Caution

What does U1603 mean?

Fault code U1603 means "Lost Communication with Instrument Panel Cluster". This is a General Motors-specific EV diagnostic trouble code for the GM Ultium / BEV3 platform. It is classified as "network" with a severity level of "caution". Applicable models: Chevrolet Equinox EV (2024+), Chevrolet Blazer EV (2024+), Honda Prologue (2024+), Cadillac Lyriq (2023+), Chevrolet Silverado EV (2024+).

Possible Causes

CAN bus communication timeout
Control module offline or not responding
Wiring harness damage or short circuit
Software version mismatch between modules

Recommended Actions

1 Schedule a diagnostic check within the next week
2 Monitor the issue for any changes
3 Check for software updates at your next service visit
4 Document any symptoms for the technician

This code applies to all vehicles. View generic U1603 information →