U0163 – Lost Communication With Navigation Display Module “B”

System: Network | Standard: ISO/SAE Controlled | Fault type: General | Location: Designator B

Definition source: SAE J2012/J2012DA (industry standard)

DTC U0163 indicates the vehicle network has detected a loss of communication with the Navigation Display Module “B.” In practical terms, one or more other modules expected to receive messages from that navigation display module but did not see them within the allowed time window, so a network communication fault was stored. The exact modules involved, message timing, and whether this sets as a current or history code can vary by vehicle, so confirm the monitor’s enable criteria and network topology using the correct service information. This DTC does not, by itself, prove the display module has failed; it only confirms a communication break that must be isolated with testing.

What Does U0163 Mean?

U0163 – Lost Communication With Navigation Display Module “B” means the networked control system has determined that communication with the Navigation Display Module “B” has been lost. Under SAE J2012 DTC structure conventions, a “U” code is a network-related fault, and this particular entry is used when the expected data exchange with that specific module is missing or invalid due to a communication interruption. The code points to a problem in the communication path (network wiring, connectors, power/ground to the module, or the module’s ability to participate on the network), not to a single guaranteed component failure.

Quick Reference

• Subsystem: Vehicle network communication for the Navigation Display Module “B” (in-vehicle data bus and related power/ground).
• Common triggers: Module offline, bus open/short, poor connector contact, low system voltage during start, or a network segment fault.
• Likely root-cause buckets: Wiring/connector issues, module power/ground faults, network backbone problems, module internal fault, configuration/software issues (varies by vehicle).
• Severity: Usually non-driveability-critical, but driver information features may be impaired; severity depends on what functions are integrated with the display.
• First checks: Verify battery/charging health, check for related network DTCs, confirm module powers up, inspect connectors and harness routing.
• Common mistakes: Replacing the display module before verifying power/ground, ignoring shared network faults, or overlooking intermittent connector/backbone issues.

Theory of Operation

The Navigation Display Module “B” is a network node that exchanges data with other modules over the vehicle communication bus. Depending on design, it may publish status and receive commands (for example, requests to display information or share positioning-related data). Other modules monitor network traffic and expect periodic messages or acknowledgments from that module. If those messages stop arriving, are corrupted, or the module no longer responds to network requests, the vehicle can set a “lost communication” DTC.

The monitor typically runs when network wake-up conditions are met and system voltage is within an acceptable range. A loss can be caused by the module losing power/ground, a disconnected connector, high resistance at terminals, damage to the bus wiring, or a network short/open that prevents messages from reaching the rest of the system. Because multiple modules share the same bus, diagnosing the communication path is critical before condemning any single module.

Symptoms

• Display inoperative: Navigation screen may stay dark, freeze, or reboot intermittently.
• Missing functions: Navigation-related menus, prompts, or connected features may be unavailable.
• Warning indicator: A warning message or general malfunction indicator may appear depending on vehicle strategy.
• Intermittent operation: Concern may occur over bumps or during temperature changes, suggesting a connection issue.
• Multiple network codes: Additional U-codes may set in other modules due to shared bus disruption.
• No communication with scan tool: The module may not respond during a network module scan.
• Battery drain: In some cases, repeated wake/sleep cycling or bus activity may contribute to abnormal key-off draw.

Common Causes

• Open, shorted, or high-resistance wiring in the network communication circuits between the Navigation Display Module “B” and the rest of the vehicle network
• Poor connector fit, backed-out pins, bent terminals, corrosion, or contamination at the Navigation Display Module “B” connector(s) or an in-line network connector
• Loss of power feed to the Navigation Display Module “B” (blown fuse, faulty relay, open in the feed circuit, or poor splice)
• Loss of ground to the Navigation Display Module “B” (open ground, loose fastener, paint/oxidation under the ground eyelet, or high resistance at a ground splice)
• Network backbone fault affecting multiple modules (short between communication lines, short-to-power/ground on the bus, or a damaged section of the main harness)
• Intermittent connection caused by harness stress, vibration, or prior repairs leading to momentary network dropouts
• Module internal fault within the Navigation Display Module “B” (communication transceiver or internal power regulation issue), after power/ground and network integrity are verified
• Configuration or software-related communication issue (module not properly configured or software anomaly), where applicable and only after electrical checks pass

Diagnosis Steps

Useful tools include a scan tool capable of full-network scanning and module identification, a digital multimeter for power/ground checks and voltage-drop testing, and basic back-probing or terminal test tools. Access to wiring diagrams and connector views for your vehicle is essential. If available, a breakout lead or non-intrusive test adapters can reduce terminal damage during testing.

1. Confirm the DTC and capture context: Perform a full-system scan, record all stored and pending codes, and save freeze-frame or event data if available. Note whether other communication or network-related DTCs are present, as they can change the diagnostic direction.
2. Verify the symptom and affected functions: Check whether the navigation display functions are inoperative, intermittent, or rebooting. If the scan tool cannot communicate with the Navigation Display Module “B,” document that as a key finding.
3. Check for network-wide impact: Use the scan tool network topology (if supported) to see which modules are offline. If multiple modules drop off the network, suspect a backbone or shared power/ground issue rather than a single module fault.
4. Inspect fuses and module wake-up conditions: Identify the power supplies for the Navigation Display Module “B” (constant battery feed and ignition/switched feed, as applicable). Check related fuses/relays and confirm they are not open and are seated correctly. If a relay is involved, verify it is being commanded on where applicable (varies by vehicle).
5. Perform a focused visual inspection: Inspect the module connectors and the harness routing for abrasion, pinch points, prior repair splices, or signs of heat damage. Look for connector damage, moisture intrusion, corrosion, or partially latched connectors. Correct obvious issues before deeper testing.
6. Verify power and ground at the module under load: With the module connected (or using an appropriate test method that keeps the circuit loaded), check the module power feeds and grounds. Use voltage-drop testing on the ground path and on the power feed path to find excessive resistance. Consult service information for which pins are power/ground on your vehicle.
7. Check communication circuit integrity: With the ignition off and following vehicle-specific guidance to prevent network/module damage, inspect the network communication circuits for opens/shorts. If service information allows, measure end-to-end continuity between relevant points and check for shorts to ground or shorts to power on the communication lines. Do not force probes into terminals; use correct adapters.
8. Wiggle test for intermittent faults: While monitoring scan-tool communication status (online/offline), gently wiggle the harness near the module, at connectors, and along known stress points. Also lightly tap connectors and observe for dropouts. If the condition changes, isolate the exact section by repeating with smaller movements.
9. Isolate the module vs. the network (vehicle-dependent): If the network shows broad instability, disconnecting one module at a time may help identify a module or branch that is pulling the network down; only do this if service information permits and the procedure is safe for the platform. If only the Navigation Display Module “B” is offline and network health is otherwise normal, focus on its power/ground and local harness branch.
10. Review live data and log events: If communication is intermittent, use the scan tool to log network status, module presence, and any related voltage or ignition status PIDs (as available). Correlate dropouts to ignition transitions, vibration, or electrical load changes to guide harness and ground testing.
11. Make a verified repair and re-test: After repairing wiring, terminals, grounds, or power feeds, clear codes and perform a drive cycle or functional test appropriate to the system. Confirm the module remains consistently communicative and that U0163 does not return as stored or pending.

Professional tip: If U0163 is intermittent, prioritize voltage-drop testing and connector terminal checks over simple continuity readings. A circuit can pass continuity with a multimeter yet fail under real load due to poor pin tension, oxidation, or a compromised splice. Logging module online/offline status during a wiggle test can quickly pinpoint the exact harness segment or connector that is failing.

Possible Fixes & Repair Costs

Repair costs for U0163 vary widely because the root cause can range from a simple connection issue to network wiring repair or a module-level fault. Accurate diagnosis determines whether the fix is labor-heavy (harness access) or part-heavy (module replacement and setup).

• Clean, reseat, and secure connectors at the navigation display module “B” and any in-line network connectors; correct poor terminal fit or backing-out pins.
• Repair wiring faults on the communication network (open, short-to-power, short-to-ground, or high resistance) found during inspection and testing.
• Restore proper module power and ground (repair blown fuse, faulty relay, poor ground point, or high-resistance power/ground wiring) verified by testing.
• Correct corrosion or moisture intrusion at connectors by repairing terminals/connectors and addressing the source of contamination.
• Perform required configuration, setup, or relearn procedures after repairs if the platform requires it (varies by vehicle; follow service information).
• Replace the navigation display module “B” only after confirming network integrity and power/ground are correct and the module remains non-communicative.

Can I Still Drive With U0163?

Usually, U0163 does not prevent the vehicle from moving, but it can disable navigation display features and may be accompanied by warnings or loss of related infotainment functions depending on how modules share data (varies by vehicle). If the vehicle also shows critical warnings (brake, steering, airbag), experiences stalling/no-start, or multiple network codes appear at once, avoid driving and diagnose immediately because a broader network or power/ground problem could be present.

What Happens If You Ignore U0163?

Ignoring U0163 commonly results in persistent loss of navigation display functionality, repeated warning messages, and intermittent or escalating network communication issues if the underlying cause is a deteriorating connector, wiring damage, or power/ground instability. In some cases, additional modules may log communication faults, complicating future diagnosis and potentially causing more features to become unavailable over time.

Last updated: March 16, 2026

Vehicles Commonly Affected by U0163

• Vehicles equipped with a separate navigation display module “B” on a shared in-vehicle network
• Platforms with multiple infotainment modules that exchange data over CAN or similar networks
• Vehicles with display modules located in areas prone to vibration or connector movement (installation location varies by vehicle)
• Vehicles with prior dash, console, or infotainment service where connectors may be partially seated
• Vehicles with known sensitivity to low battery voltage or poor grounds affecting network stability
• Vehicles with aftermarket electrical accessories that may disturb power, ground, or network routing (if present)
• Vehicles operated in environments that promote connector corrosion or moisture intrusion
• Vehicles with harness routing near moving components where chafing can occur (varies by vehicle)

To confirm the fix, ensure the navigation display module “B” consistently appears on the network during repeated key cycles, no U0163 returns after a road test, and related functions remain stable without intermittent dropouts.