U0163 – Lost communication with navigation control module

U0163 means the vehicle lost communication with the navigation control module, so the map screen, routing, or GPS position may stop working. You may also lose related features like the clock sync, compass display, or some driver-assist map-based functions. According to factory diagnostic data, this code indicates the network cannot exchange valid messages with the navigation control module for a set period. The code does not prove the module failed. It only proves other modules stopped “hearing” it. Your first job is to confirm whether the navigation module is offline, unpowered, or blocked by a network wiring fault.

U0163 Quick Answer

The U0163 code points to a network communication loss with the navigation control module. Check module power/ground and the network wiring at the nav unit before replacing any parts.

What Does U0163 Mean?

Official definition: “Lost communication with navigation control module.” In plain terms, one or more control modules expected navigation data but did not receive it. In the real world, the infotainment system may show a navigation error, GPS may freeze, or the map may disappear. Some vehicles also disable functions that depend on nav data, even if the engine runs normally.

What the module is checking: The vehicle’s network controller(s) monitor message traffic and module “presence” on the bus. When the navigation control module stops sending expected messages, or other modules cannot request data and get a valid response, they store U0163. Why it matters: communication loss can come from a dead module, but it more often comes from lost power/ground, a loose connector, water intrusion, or a network short that drags the bus down.

Theory of Operation

Under normal conditions, the navigation control module powers up with the key cycle and joins the vehicle network. It then transmits identification and operating messages over the communication bus used on that platform. Other modules and the scan tool “see” it in a module list and can request data like GPS location, time sync, map status, and diagnostics.

U0163 sets when that message flow stops. A blown fuse, high-resistance ground, or intermittent wake-up feed can make the module drop offline. Harness damage can also distort network signals, so other modules stop decoding navigation messages. On many vehicles the nav module sits in the dash, trunk, or rear quarter panel, so connector fretting, amplifier moisture, or pin fit issues show up often after body work or water leaks.

Symptoms

U0163 symptoms usually show up first as a “missing module” on a scan tool and a dead or unstable navigation display.

• Scan tool: navigation control module missing from the network scan, shows “no communication,” or drops in and out during a module list refresh
• Navigation function: map screen blank, “GPS unavailable,” or route guidance stops mid-drive
• GPS behavior: position frozen, incorrect location, or no satellite acquisition after a key cycle
• Infotainment: head unit reboots, screen lags, or certain menus fail to load when nav is selected
• Clock/compass: time will not auto-update, compass heading disappears, or map-based compass data becomes erratic
• Related features: traffic data, speed-limit display, or other map-linked driver info becomes unavailable (if equipped)

Common Causes

• Navigation control module power loss: A blown fuse, failed relay, or open feed circuit powers the module down, so other modules stop receiving its network messages.
• High-resistance ground at the navigation module: Corrosion or a loose ground eyelet lets the module boot intermittently, which makes communication drop in and out.
• Connector pin fit or corrosion at the navigation module: Spread terminals, moisture, or green corrosion increases resistance and causes an intermittent “no response” condition on the network.
• Open or short in CAN/LIN communication wiring near the module: A chafed harness, aftermarket fastener, or track damage can interrupt the data path and trigger U0163.
• Network fault on the same bus segment: Another module or a wiring short can pull the bus down, which prevents the scan tool and other ECUs from talking to the navigation module.
• Aftermarket radio/navigation integration issue: Incorrect splices, adapters, or harness conversions can load the network or remove the module’s power/ground reference.
• Low system voltage or unstable ignition feed: Battery or charging issues can reset the navigation module during crank or idle, which looks like lost communication.
• Module internal fault (uncommon): Internal processor or transceiver problems can stop the module from responding, but you must prove power, ground, and network integrity first.

Diagnosis Steps

Use a bidirectional scan tool that can run a full network scan, plus a DVOM for voltage-drop testing. Pull the correct wiring diagrams for power, ground, and the exact network type (CAN or LIN). Keep back-probe pins, terminal tension tools, and a fused jumper handy. A scope helps on tough intermittent network dropouts.

1. Confirm U0163 in all modules and record freeze-frame data. For U0163, focus on ignition state, vehicle speed, battery voltage, and any other U-codes stored at the same time. Save the report so you can compare results after repairs.
2. Run a complete network scan and check whether the navigation control module appears. If the module does not show up, treat it as “offline” and prioritize power/ground and bus integrity. If it shows up, compare “current” vs “history” U0163 to decide if the fault is intermittent.
3. Check for pending versus confirmed/stored U0163 and note the status. Many communication faults behave like Type B logic on some platforms, so a pending code may indicate a one-time dropout. A hard network or power fault often returns immediately at key-on after clearing.
4. Check fuses, relays, and power distribution that feed the navigation control module before you probe the module connector. Verify the circuit with a test light or loaded meter test, not continuity alone. Replace nothing yet.
5. Verify navigation module power and ground under load with voltage-drop tests. With the module connected and operating, measure B+ drop from battery positive to the module B+ pin. Then measure ground drop from module ground pin to battery negative, and keep it under 0.1V with the circuit active.
6. Inspect the navigation module connector and nearby harness in detail. Look for water tracks, loose locks, backed-out pins, and terminal drag issues. Pay close attention to areas near the head unit, trunk-mounted modules, and under- routing where harness damage is common.
7. With ignition ON, check network line bias at the navigation module connector. Do not use ignition-OFF readings as a reference because network bias only exists when modules power up. If bias looks wrong or unstable, move to bus isolation checks using the service information for that vehicle.
8. Perform circuit integrity checks between the navigation module connector and the network splice or gateway connector. Use a wiggle test while watching scan tool module presence and U-code status. If you find an intermittent change, pinpoint the exact harness section or connector that triggers the dropout.
9. Use the scan tool to attempt direct communication with the navigation module if it appears in the network list. Pull identification data and run any available module self-tests. If the scan tool drops the session during testing, re-check power/ground drops and connector pin fit.
10. Clear codes, then perform a key-cycle and an operational road test to confirm the repair. Capture a scan tool snapshot during the test drive if the concern is intermittent, and compare it to freeze-frame conditions. Re-scan the network and verify U0163 does not return as pending or confirmed.

Professional tip: Treat U0163 like a “module offline” problem until proven otherwise. Prove the navigation module has solid power and a low-resistance ground with voltage-drop under load. Only then move to network diagnostics and module condemnation.

Possible Fixes

• Repair power feed, ignition feed, or fuse/relay issues that remove power from the navigation control module.
• Clean, tighten, and rework grounds, then confirm less than 0.1V ground drop under load.
• Clean corrosion and restore terminal tension at the navigation module connector and any inline connectors.
• Repair chafed, pinched, or shorted CAN/LIN wiring and correct any damaged splices.
• Remove or correct faulty aftermarket radio/navigation wiring that loads the network or disrupts module power.
• Update module software if the OEM procedure addresses known communication dropouts for that platform.
• Replace the navigation control module only after you verify power, ground, and network circuits test good.

Can I Still Drive With U0163?

You can usually drive with a U0163 code because it points to lost communication with the navigation control module, not a powertrain failure. Expect reduced infotainment functions. The map, guidance, compass heading, or “NAV” screen may go blank or reboot. Some vehicles also route vehicle settings through the same display, so convenience features can act up. Treat it differently if the radio cluster also drops off the network. If you lose the instrument cluster, multiple modules set U-codes, or the vehicle shows battery drain, stop driving and diagnose the network. A shorted data line can take down more than navigation.

How Serious Is This Code?

U0163 ranges from an inconvenience to a clue that the network has a broader problem. When only navigation quits, severity stays low and drivability usually remains normal. The risk rises when you also see multiple “lost communication” codes, intermittent no-start, or repeated module resets. Those patterns point to CAN bus instability, shared power feed issues, or a wiring fault that can spread. Some platforms tie navigation into driver assistance displays, backup camera processing, or vehicle configuration menus. In those cases, the loss can reduce situational awareness and lead to unsafe driver decisions. Fix U0163 sooner if the fault is confirmed, the code returns quickly, or the vehicle shows other network symptoms.

Common Misdiagnoses

Technicians often replace the navigation module or screen because the symptom looks like a “dead NAV unit.” That move wastes money when a fuse, ground eyelet, or connector causes the loss. Another common mistake involves clearing codes before checking network scan results. You lose valuable evidence, like whether the nav module dropped off the bus during crank. Many miss shared circuits. The nav module often shares ignition power, ground, or CAN splices with the radio amplifier or telematics unit. Water intrusion at the A-pillar, roof antenna lead, or trunk harness also fools people into blaming the module. Confirm power and ground with a voltage-drop test under load, then verify CAN integrity before condemning hardware.

Most Likely Fix

The most common confirmed U0163 repair direction is restoring the navigation control module’s power or ground, then proving stable network communication. Start with the basics that fail in real cars: an open fuse, loose ground point, or backed-out connector pin at the nav module, radio stack, or network splice pack. The next frequent fix involves repairing harness damage or corrosion that creates high resistance on the CAN lines near the center console, kick panel, or trunk. Only consider module replacement after the scan tool cannot consistently see the module and you have verified correct power, ground, and CAN bus continuity and isolation.

Repair Costs

Network and communication fault repairs vary by root cause — wiring/connectors are often the source, but module-level repairs or replacements can be significantly more expensive.

Last updated: April 2, 2026