U1114 – Lane Keeping Assist (LKA) angle message lost (BYD)

U1114 means your BYD Dolphin may stop offering reliable Lane Keeping Assist, or it may disable the feature altogether. You can still steer the car normally, but the lane centering support can drop out without warning. According to BYD factory diagnostic data, this code indicates the Lane Keeping Assist (LKA) angle message is lost on the vehicle network. That wording matters. It points to a communication or message-availability problem, not an immediate proof that a camera, steering part, or sensor has failed. The next job is to find which module stopped sending the angle message, or which module stopped receiving it.

U1114 Quick Answer

U1114 on a BYD Dolphin means the control modules no longer see the expected LKA angle message on the network. Diagnose it like a network/message loss fault first, not a parts failure.

What Does U1114 Mean?

Official definition: “Lane Keeping Assist (LKA) angle message lost.” In plain terms, a BYD control module expected an LKA “angle” value and did not receive it. When that happens, the car may disable LKA, show an ADAS warning, or log multiple network-related faults.

What the module actually checks: the receiving module monitors message presence and freshness on the in-vehicle network. It expects an LKA angle message to arrive within a set time and with valid counters. When the message stops arriving, arrives corrupted, or fails a validity check, it stores U1114. Why that matters: the DTC identifies a suspected trouble area, not a failed part. You must confirm whether the sender went offline, the receiver lost network access, or the data became invalid due to power, ground, wiring, or network integrity issues.

Theory of Operation

On BYD platforms, Lane Keeping Assist relies on multiple modules sharing data over the vehicle network. A sensing module calculates lane position and a steering-related angle command or reference angle. That value then travels as a network “message” to other modules that decide whether to assist steering, warn the driver, or disable the function.

U1114 sets when the receiving module does not see the LKA angle message when it. Common triggers include a module reset, poor power or ground to a key ADAS module, network wiring issues, or a gateway that drops messages. Intermittent faults often happen during low-voltage events, connector movement, or moisture intrusion.

Symptoms

These are the most common signs technicians and owners report with U1114 on BYD vehicles.

• Scan tool ADAS-related module shows “no communication,” disappears from the module list, or drops out intermittently during a full vehicle scan
• LKA disabled lane keeping assist unavailable or cancels shortly after enabling
• ADAS warning driver assistance warning message or indicator in the cluster
• Lane markings lane line display disappears or flickers on the driver information screen
• Intermittent operation LKA works at startup, then fails after bumps, turns, or temperature change
• Multiple U-codes other “message lost” codes stored in steering, brake, or ADAS controllers
• Event-related fault appears after 12V battery service, jump start, or low-voltage condition

Common Causes

• Intermittent CAN network dropout to the LKA message path: Momentary loss of network communication prevents the Lane Keeping Assist angle message from reaching other BYD modules.
• High resistance in CAN wiring or splices: Corrosion, poor crimps, or damaged splice packs distort the data signal and trigger a “message lost” fault.
• Connector fretting or water intrusion at an ADAS or gateway connector: Micromovement or moisture increases contact resistance and causes brief communication interruptions.
• Power supply instability to the transmitting module: A weak feed, loose fuse terminal, or failing relay resets the module and stops the LKA angle broadcast.
• High-resistance ground at the transmitting module or gateway: The module stays “alive” on a meter test but drops out under load and stops sending the message.
• Harness damage near the windshield/roofline or front body harness routes: Pinched or rubbed wiring creates opens or shorts that disrupt the network segment used by LKA-related messages.
• Network termination or shielding issue on the affected bus segment: A missing or compromised termination path increases reflections and produces sporadic message loss.
• Software/configuration mismatch after a repair or update: Incorrect coding or an incomplete update can stop the expected LKA angle message from being published on the BYD network.
• Transmitting module internal fault or thermal reset: An internal failure can halt the message stream even when power and ground look normal at first.

Diagnosis Steps

You need a scan tool that can run a full BYD network scan and view live data for LKA/ADAS-related modules. Use a DVOM for voltage-drop testing under load. A two-channel oscilloscope helps confirm CAN integrity during an intermittent dropout. Have wiring diagrams and connector views for the BYD Dolphin platform you are servicing.

1. Confirm U1114 and record freeze frame and DTC status. Focus on ignition state, vehicle speed, battery voltage, and any related network/ADAS codes. Save the report so you can compare after repairs.
2. Run a full network scan and note which modules do not respond. A “message lost” code often pairs with a module that drops offline. If the suspected LKA/ADAS transmitter or gateway does not appear, treat it as a power/ground or network backbone problem first.
3. Check fuses and power distribution that feed the likely transmitting module and any gateway/ADAS controllers. Inspect fuse blades and the fuse box terminals for heat discoloration or looseness. Do not jump to ECU connector probing until you prove the power supply path stays stable.
4. Verify module power and ground with voltage-drop testing under load. Load the circuit with the module connected and operating. Keep ground drop under 0.1 V while the circuit runs, or repair the ground path before anything else.
5. Perform a careful harness and connector inspection along the suspected message path. Focus on connectors that serve ADAS/gateway areas and any harness routing near the windshield, dash, and front body channels. Look for water tracks, green corrosion, bent pins, pin fit issues, and harness rub-through.
6. Check for intermittent faults by manipulating the harness while monitoring live data. Watch for the LKA angle value to freeze, drop out, or show “not available.” Use a scan tool snapshot to capture the moment the message disappears. Freeze frame shows when the DTC set, while a snapshot helps catch the dropout during testing.
7. Evaluate pending versus confirmed behavior after clearing codes. Many network faults behave like Type B logic in practice, where a single dropout sets pending and repeated events store a confirmed code. If U1114 returns immediately at key-on, you likely have a hard fault or a module that stays offline.
8. Measure CAN circuit bias and activity with ignition ON, not OFF. Communication line bias exists only with the network powered. Use the DVOM for basic checks, then confirm signal quality with an oscilloscope if the fault stays intermittent or load-related.
9. If scope access is available, check CAN waveform integrity during the fault. Look for noise, ringing, dropouts, or a line that intermittently sticks dominant or recessive. Correlate the waveform event to the snapshot timestamp or the driver-reported symptom window.
10. Isolate the fault to a segment if the platform design supports it. Disconnect one suspect module at a time only when service information allows it, and only with ignition OFF. Recheck network operation and module presence after each change.
11. After repairs, clear DTCs and run the same conditions shown in freeze frame. Confirm the LKA angle message stays present in live data and the module list remains stable. Complete a road test and re-scan to verify U1114 stays cleared.

Professional tip: Treat U1114 as a network integrity problem until you prove the message source stays powered, grounded, and online. Many technicians chase the “angle” wording and replace sensors. The faster path uses a network scan, voltage-drop under load, and a snapshot during a wiggle test to catch the exact moment the message drops.

Possible Fixes

• Repair power feed issues: Restore stable power at the transmitting module or gateway by correcting loose fuse terminals, relay faults, or damaged feed wiring.
• Repair ground path resistance: Clean and re-secure ground points, then confirm less than 0.1 V drop under load with the module operating.
• Repair CAN wiring/connector defects: Fix pin fit, corrosion, water intrusion, or damaged wiring, then recheck network scan stability.
• Restore harness routing protection: Repair chafed sections and add proper abrasion protection to prevent repeat dropouts.
• Correct software/configuration issues: Perform the correct BYD programming, calibration, or configuration steps when service information shows a mismatch.
• Replace a module only after verification: If the network and power/grounds test good and the module repeatedly drops offline, replace the verified failed module and complete required setup.

Can I Still Drive With U1114?

You can usually drive a 2020 BYD Dolphin with U1114, but you should treat the Lane Keeping Assist system as unavailable or unreliable. U1114 means the network lost the LKA angle message, so the driver-assist logic cannot trust steering or path-control inputs. Expect LKA warnings and a feature shutdown. Keep full control of steering at all times. Avoid relying on any lane-centering or lane-keep corrections until you confirm the fix. If the warning appears with other network codes, or if you notice heavy steering, unstable steering feel, or multiple ADAS faults, stop and diagnose the power and network basics first.

How Serious Is This Code?

U1114 ranges from an inconvenience to a safety concern, depending on what else fails with it. If only LKA drops out, the car remains drivable and the impact stays limited to ADAS functionality. The risk rises when U1114 appears with other U-codes, voltage faults, or intermittent module resets. Those patterns point to a wider CAN communication problem that can affect braking assist, stability control coordination, or steering support messages. Treat any simultaneous steering, brake, or stability warnings as a priority. Also remember this is an ADAS-related fault. If you replace or disturb any camera, steering, or driver-assist module, BYD calibration or initialization may be required before the system is safe to use.

Common Misdiagnoses

Technicians often replace the camera or an LKA-related module because the message says “angle,” then miss the real issue: the network could not deliver the message. The most common waste happens when no one checks module power and ground integrity under load. A small voltage drop can reboot a sender module and “lose” the message. Another frequent mistake involves clearing codes and returning the car without a road test that recreates the drop-out. Shops also skip checking for stored companion U-codes in other modules, which usually identify the actual sender or bus segment. Confirm which module broadcasts the LKA angle message on this BYD platform before you touch parts.

Most Likely Fix

The most frequently confirmed repair direction for U1114 involves restoring reliable communication, not replacing an angle-related component. Start with connector and harness checks at the likely message sender and the module logging U1114, especially for backed-out pins, moisture, or fretting corrosion. Next, verify clean power and ground to those modules with a loaded voltage-drop test. If you find intermittent resets or multiple U-codes, correct the power feed, ground splice, or network wiring issue first. After repairs, confirm the message stays present during a drive under the same conditions that originally set the fault. Enable criteria vary by BYD system, so use service information to match the conditions.

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: March 29, 2026