U0073 – Sending fault (navigation to APGS)

Last updated: April 7, 2026

U0073 means the vehicle cannot reliably send navigation information to the APGS system, so parking guidance features may disable or act inconsistently. You will often notice a parking assist message, missing guidance lines, or the system refusing to start. According to manufacturer factory diagnostic data, this code indicates a “Sending fault (navigation to APGS).” In plain terms, one module tries to transmit navigation-related data, and the APGS module does not receive usable messages. Because U-codes are intentionally general by SAE design, you must confirm which module, network path, or power/ground feed caused the sending failure.

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U0073 Quick Answer

U0073 points to a communication send problem between the navigation function and the APGS module. Start with a full network scan, then verify power/ground integrity at the navigation and APGS-related modules before chasing wiring.

What Does U0073 Mean?

Official definition: U0073 – Sending fault (navigation to APGS). In practice, a module expected to provide navigation-derived data for Automated Parking Guidance (APGS) reports that its message did not transmit correctly or did not complete in a valid way. That can disable APGS features or remove navigation-based guidance elements during low-speed parking maneuvers.

What the module checks: the sending module monitors message handling on the vehicle network and its own internal ability to publish the required navigation-to-APGS data. The code does not prove a bad APGS module or a bad navigation unit. Why it matters: a “sending fault” can come from network integrity problems, module power/ground voltage-drop, connector resistance, or software/state issues, so you must prove the failure with scan tool network status and electrical tests.

Theory of Operation

Under normal conditions, the navigation system (or a gateway/infotainment controller that hosts navigation data) broadcasts specific data frames onto the vehicle network. The APGS module uses those frames to improve parking guidance logic and on-screen prompts. The network may involve CAN, Ethernet, or a gateway translating between buses, depending on the platform.

U0073 sets when the sending side cannot place the navigation-to-APGS message on the network in a valid way, or when internal diagnostics flag a failed transmit event. Low system voltage, poor module grounds, bus-off events, gateway congestion, or connector pin fit issues can all break message transmission. Because OEMs can map “navigation to APGS” through different modules, you must confirm the actual sender and the network route on the vehicle you.

Symptoms

U0073 symptoms usually show up first as scan tool network irregularities or APGS feature shutdown.

• Scan tool symptoms: APGS and/or navigation-related module shows intermittent communication, drops off the module list, or logs multiple U-codes with timeouts
• APGS disabled: automated parking assist refuses to start or cancels immediately after activation
• Missing guidance: parking guidance overlays, direction prompts, or navigation-referenced cues do not display or flicker
• Warning message: “Parking Assist Unavailable” or similar driver information message appears during low-speed maneuvers
• Intermittent operation: APGS works after a key cycle, then fails again after driving or after an infotainment reboot
• Related DTCs: additional network codes appear in gateway, infotainment, or ADAS modules, often as “lost communication” companions
• Voltage sensitivity: symptoms worsen with heavy electrical loads, cold starts, or after battery service

Common Causes

• Navigation unit missing from the network (offline): If the navigation module drops off the bus, it cannot transmit the required data to APGS and U0073 sets as a sending fault.
• APGS module not receiving due to network path fault: A fault in the communication path can block or corrupt navigation-to-APGS messages even when both modules power up.
• High-resistance power or ground at the navigation module: Voltage drop under load can make the navigation unit reset or brown out, which interrupts message transmission.
• High-resistance power or ground at the APGS module: APGS can miss or reject incoming navigation messages if its supply voltage dips during operation.
• CAN bus open circuit on CAN+ or CAN-: An open conductor changes bus impedance and prevents reliable message delivery between navigation and APGS.
• CAN bus short to ground, short to power, or short between CAN lines: A short forces the bus dominant or distorts bit timing, so the navigation messages never reach APGS correctly.
• Connector fretting, corrosion, or water intrusion at an in-line junction: Intermittent contact at a splice, gateway, or junction connector can cause a “sending fault” that appears during vibration or temperature change.
• Incorrect module configuration or software mismatch: If coding, variant setup, or software levels do not match, APGS may treat the navigation message as invalid and log U0073.

Diagnosis Steps

Tools you need include a scan tool with full network scan and freeze frame access, a DVOM with min/max, and a wiring diagram for the vehicle. Have back-probe pins and terminal inspection tools ready. For CAN testing, use an ohmmeter with the battery disconnected and a voltmeter with ignition ON. A lab scope helps with intermittent bus noise, but it is not required.

1. Confirm U0073 on a full vehicle scan and record freeze frame data. For this communication code, note ignition state, vehicle speed, battery voltage, and any related network or module DTCs. Save the scan report so you can compare after repairs.
2. Run a network scan and verify whether the navigation module and APGS appear as “online.” If either module shows “no communication,” treat that as your lead. Check for pending vs confirmed status. A pending U0073 often points to an intermittent network issue.
3. Check fuses and power distribution for both modules before probing module connectors. Verify each related fuse carries load and not just continuity. Inspect the fuse box for heat damage or loose terminals that can drop voltage under vibration.
4. Voltage-drop test the navigation module power and ground under load. Turn ignition ON and command the module awake if the scan tool allows it. Measure power feed drop from battery positive to the module feed. Measure ground drop from module ground to battery negative. Keep ground drop under 0.1V while the circuit operates.
5. Voltage-drop test the APGS module power and ground under load using the same method. Watch DVOM min/max during module wake-up because many faults show up during inrush current. If you see excessive drop, repair the supply or ground path before any network work.
6. Inspect connectors and harness routing between navigation, APGS, and any gateway or junction points. Look for pushed pins, backed-out terminals, water tracks, corrosion, and fretting marks. Pay attention to areas near kick panels, trunk side cavities, and under- harness runs. Perform a light tug test on suspect wires.
7. Check CAN bus resistance with ignition OFF and the battery disconnected. Measure resistance between CAN+ and CAN- at an accessible module connector or DLC if the wiring diagram confirms it reads the same segment. A healthy high-speed CAN network typically reads about 60 ohms. Readings near 120 ohms or OL suggest an open or missing termination. Very low resistance suggests a short.
8. Check CAN bias voltages with ignition ON. Measure CAN+ to ground and CAN- to ground at a safe back-probe point. Healthy bias usually sits near 2.5V on both lines at rest. Do not use ignition-OFF voltages as a reference because the network bias appears only when powered.
9. If resistance or bias readings look wrong, isolate the fault by unplugging modules one at a time on the affected network segment. Repeat the resistance and bias checks after each disconnect. This process helps you find a shorted module, a shorted branch, or an open in a specific leg.
10. If the bus tests pass, use the scan tool to monitor related data and states. Look for navigation status, GPS/navigation output status, APGS readiness, and any “message not received” counters if available. Use a scan tool snapshot during a road test or parking maneuver to capture intermittent dropouts. Freeze frame shows what happened when U0073 set. A snapshot captures the moment the concern occurs during testing.
11. After repairs, clear codes and perform a repeat network scan. Recreate the operating conditions that set U0073. Confirm the code does not return as pending or confirmed. If the monitor behaves like a two-trip (Type B) logic on that platform, complete two key cycles and a repeat maneuver to verify the fix.

Professional tip: If U0073 sets only during parking assist use, wiggle-test the harness while monitoring the network “online/offline” list. Focus on junction connectors and splices near the rear bumper and trunk. Those areas see moisture and flex. Fixing a 0.2V ground drop often restores stable communication without replacing any module.

Possible Fixes

• Repair power or ground drops to the navigation module or APGS: Clean and tighten ground points, repair overheated fuse terminals, and restore proper feed voltage under load.
• Repair CAN wiring faults: Correct opens, shorts, or pinched sections on CAN+ or CAN- and restore proper bus resistance and bias voltage.
• Clean, dry, and re-pin damaged connectors: Remove corrosion, address water intrusion sources, and replace terminals that show fretting or poor pin tension.
• Repair harness routing and strain points: Re-route or secure wiring that rubs, stretches, or gets pinched during movement, trim installation, or trunk loading.
• Update module software or correct configuration: Reflash or re-code modules when the network is healthy but message validity or compatibility problems trigger the sending fault.
• Replace a verified faulty module only after testing: Replace the navigation unit, APGS, or gateway only after power/ground, connector integrity, and CAN integrity checks confirm the module causes the fault.

Can I Still Drive With U0073?

You can usually drive with a U0073 code, but expect feature loss and inconsistent operation. This DTC points to a network sending fault between the navigation system and APGS (often “Advanced Parking Guidance System”). In plain terms, the vehicle may not trust guidance data, or it may stop receiving it. That can disable automatic parking prompts, camera overlay guidance, or park-assist steering support. Treat this as a safety concern in tight spaces. You still control the vehicle, but you may lose alerts or guidance you rely on. If parking assist behaves unpredictably, stop using it until you repair the fault. If other network codes appear with U0073, avoid driving far until you confirm basic module communication and stable battery voltage.

How Serious Is This Code?

U0073 ranges from an inconvenience to a real safety and drivability risk, depending on what else shares the network. When only the navigation-to-APGS message path fails, the result often stays limited to parking assist features. That is mostly an inconvenience. Severity increases when the fault reflects a broader bus problem, low system voltage, or a module that drops offline. In that case, you can see multiple U-codes, warning messages, and intermittent driver-assist behavior. Any time APGS or related ADAS-type features need calibration after repair, you must complete the required initialization before trusting the system. Do not assume a new module or repaired wiring makes the feature safe. Confirm operation with a scan tool and perform any OEM calibration routines listed in service information.

Common Misdiagnoses

Technicians often replace the navigation unit or APGS module too early because the title mentions “sending fault.” That wastes time and money. The code does not prove a module failed. U0073 can set when a module browns out, resets, or loses ground under load. Corroded grounds near the luggage compartment or under- harness splices commonly mimic “bad modules.” Another common mistake involves ignoring pending vs confirmed status and not checking freeze frame or event records. Intermittent network dropouts can leave no obvious damage. A quick module ping test can also mislead you if the fault occurs only while shifting into reverse or while the camera powers up. The right path starts with a full network scan, module presence, power/ground voltage-drop tests, and connector inspection at the navigation and APGS modules before any parts ordering.

Most Likely Fix

The most common repair direction for U0073 involves restoring stable power, ground, and connector integrity to the navigation and APGS modules, then confirming clean communication on the involved network path. . After the electrical repair, verify the fix by running the same conditions that set the code. That often means repeated reverse engagements and a short drive with parking assist enabled. Enable criteria vary by model, so use service information to confirm the validation drive pattern.

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.