OBD-II trouble code
U0163: Lost Communication With Navigation Control Module
The navigation computer is missing from the bus. It is usually mounted under a seat or in the cargo area, which means the two things that kill it are liquids and luggage — and neither of those is a wiring fault you find by tracing the harness.
Quick facts
- System
- Network
- Category
- Network Communication
- Severity
- Low severity
- Drivable
- Usually safe to drive short-term
- Repair cost range
- $100 – $1,500
- DIY difficulty
- Advanced DIY
What does U0163 mean?
A module on the network expected periodic messages from the navigation control module and is no longer receiving them. The control module is the computing side of the navigation system: it takes satellite position, combines it with vehicle inputs such as road speed and yaw to keep tracking through tunnels and urban canyons, holds the map data, and calculates routes. It is not the screen, and that distinction shapes everything about this diagnosis.
Start with where the thing physically is. Unlike the screen, which has to be in front of the driver, the navigation computer has no reason to be anywhere visible, so manufacturers put it where there is space: under a front seat, behind a cargo-area trim panel, in the spare wheel well, or under the parcel shelf. That location is not a detail. It determines the failure modes, and the failure modes for a module in those places are not the ones you would look for in a dash-mounted unit.
Liquids are first. A module under a seat sits directly beneath the most reliable source of spilled drinks in any vehicle, and one under a cargo floor sits in the lowest point of a compartment that fills with water when a tail light seal, a boot lid drain or a rear screen bond starts to leak. Water reaches the connector, corrosion follows over weeks, and the module intermittently drops off before it disappears for good. Lifting the seat or the boot floor and looking for staining, corrosion or a damp carpet underlay answers this faster than any electrical test.
Mechanical damage is second, and it is just as location-specific. A module under a seat is in the path of the seat rails every time the seat is adjusted, and it is where feet and cargo end up. A module in the cargo area is in the way of everything that gets loaded and unloaded. Add to that the fact that these are exactly the places installers choose to mount amplifiers, subwoofers and alarm sirens — so a module in that space frequently has aftermarket hardware bolted alongside it and its connectors disturbed by whoever fitted it.
There is one distinction that saves a great deal of wasted effort here. Losing communication with the navigation computer and losing satellite reception are two entirely different faults with two entirely different causes, and they are constantly confused. A damaged or disconnected antenna lead — a very common finding, since that lead runs from the module all the way to the windscreen or roof — produces a system that cannot establish position. It does not remove the module from the network, so it does not set this code. Conversely, this code means the module is absent from the bus, which is a power, ground, wiring or module failure and has nothing to do with satellites. If the complaint is that the screen works and the map says it is searching for a signal, the antenna is worth checking but this code is not the reason.
The presentation follows from all this: the screen usually still works, because the display module is a separate unit and is still on the bus. What is missing is position, routing and any information the vehicle draws from navigation data. The vehicle drives normally and no safety function is affected.
One last consideration. On vehicles whose navigation computer stores maps on an internal drive rather than in solid-state memory, a failing drive can cause the module to hang during start-up and drop off the network intermittently before failing outright. That pattern — works sometimes, takes a long time to come alive, eventually stops appearing — points at the module itself rather than at its wiring.
Common causes
- Liquid ingress at an under-seat mounting from spilled drinks, followed by connector corrosion
- Water in the cargo area or spare wheel well from a tail light seal, boot lid drain or rear screen leak reaching a module mounted at the lowest point
- Mechanical damage or connector disturbance from seat rail movement, cargo loading or feet
- Connector unseated during installation of an amplifier, subwoofer or alarm siren in the same space
- Corroded ground point in the cargo area, which is where road salt and moisture collect
- Blown supply fuse or lost power feed to the module
- Internal drive or memory failure on units that store map data locally, causing intermittent start-up hangs
- Fault on the media network or gateway, in which case other modules on that bus are missing too
Symptoms
- Screen still works normally but shows no position and cannot calculate a route
- Navigation reporting that it is initialising or unavailable rather than searching for satellites
- Vehicle position lost or frozen at a location it was last at
- Any feature that consumes navigation data — predictive shifting, curve speed warnings, time-zone or clock setting — behaving oddly
- Fault that comes and goes at first and then becomes permanent
- Damp carpet, staining or corrosion found under the seat or cargo floor
- Onset traced to a car audio or alarm installation
- Vehicle otherwise driving completely normally
Diagnostic steps
- 1.Find out where this module is physically mounted on this vehicle before doing anything electrical. Under-seat and cargo-area mountings change the whole approach.
- 2.Lift the seat, the boot floor or the trim panel and inspect for water staining, damp underlay, salt and green corrosion at the connector. This is the highest-yield inspection on the code.
- 3.If water is found, trace where it came in — tail light seal, boot lid drain, rear screen bond — and fix the leak, or the replacement module will fail the same way.
- 4.Look for aftermarket hardware installed in the same space and check whether the module's connector was disturbed when it went in.
- 5.Do not chase the GPS antenna on this code. A damaged antenna lead prevents a position fix but leaves the module on the network, so it cannot be the cause of a lost-communication fault.
- 6.Scan all modules and note which respond. Several missing on the same network points at the bus or gateway rather than at this module.
- 7.Check the supply fuse, and confirm power and ground at the module connector with the ignition on.
- 8.Inspect the cargo-area ground point specifically, since that is where salt and moisture accumulate on most vehicles.
- 9.If supply, ground and wiring are proven and the module still will not appear — particularly if it used to come alive slowly before failing — suspect internal failure and check for a software update before replacing it.
Repair cost
$100 – $1,500
Diagnosis is $100 to $220. Where water is the cause, budget for two jobs rather than one: the connector or module work plus the leak that caused it, and a tail light seal or boot drain repair is $80 to $400 on its own. Ignoring the leak means replacing the module twice. Connector, ground and fuse repair is $120 to $400. Module replacement with programming is $500 to $1,500, and on vehicles where map data is licensed to the unit there may be an additional cost to activate or transfer it — worth confirming before ordering the part.
Estimate your repair
Run the numbers for your vehicle
Open the Repair Cost Estimator with module communication / can bus diagnosis preselected. Adjust labor rate and vehicle category to fit your situation.
DIY vs shop
This is an advanced DIY job. It typically requires specialty tools, scan-tool access, lifting equipment, or careful sequencing to avoid causing new failures. Plan for extended downtime and have a backup vehicle. Most owners are better served by a shop that has done this repair before.