U0124 – Lost Communication With Lateral Acceleration Sensor Module

Last updated: April 7, 2026

U0124 means one or more control modules stopped receiving messages from the Lateral Acceleration Sensor Module, so stability and traction features may reduce or shut off. You may notice an ABS/ESC warning and a change in how the vehicle responds during quick turns. According to manufacturer factory diagnostic data, this code indicates “Lost Communication With Lateral Acceleration Sensor Module.” U-codes stay intentionally general by SAE design, so the code does not prove a bad sensor module. It only proves a network communication problem occurred. Your job is to confirm whether the module went offline from lost power/ground, a network wiring fault, or an internal module failure.

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U0124 Quick Answer

U0124 points to a network communication loss with the lateral acceleration sensor module. Start by checking if that module appears on a full network scan, then verify its power, ground, and network connector condition before replacing anything.

What Does U0124 Mean?

Official definition: U0124 – Lost Communication With Lateral Acceleration Sensor Module. In plain English, another module (often ABS/ESC related) expected data from the lateral acceleration sensor module and did not get it. That missing data can disable or limit ESC, traction control, and sometimes ABS-related functions. The vehicle may still drive, but it may not manage skids the same way.

What the module checks: a controller monitors network message traffic and expects periodic lateral acceleration information. When those messages stop, arrive corrupted, or time out, it stores U0124 and may set warning indicators. Why that matters: the DTC identifies a suspected communication problem area, not a confirmed failed module. Power/ground loss, connector fretting, water intrusion, or a bus fault can all produce the same “lost communication” result.

Theory of Operation

Under normal operation, the lateral acceleration sensor module measures side-to-side acceleration and shares that data across the vehicle network. The ABS/ESC system uses it with steering angle and yaw rate inputs. Those values help the controller decide when to brake individual wheels. The data travels as network messages, not as a single analog voltage.

U0124 sets when the receiving module stops seeing the expected messages within a calibrated time. A simple power dropout can take the sensor module offline. A network fault can also block messages even when the module still powers up. Common blockers include high resistance at a splice, corrosion in a connector, or a short that drags the bus down and makes multiple modules drop out.

Symptoms

U0124 symptoms usually show up as stability-control warnings and scan tool communication issues.

• Scan tool behavior: the lateral acceleration sensor module does not respond, disappears from the module list, or drops out intermittently during a network scan
• ESC/traction warning: stability control and traction control lights on, with features disabled or limited
• ABS indicator: ABS light on or an ABS message displayed, depending on how the vehicle flags ESC faults
• Reduced stability assist: the vehicle feels less controlled during abrupt lane changes or slippery turns
• Multiple U-codes: additional “lost communication” codes stored in ABS/BCM/PCM because one network issue affects several modules
• Intermittent operation: warnings that clear after a restart, then return after driving over bumps or during wet weather
• No drivability change: engine performance often feels normal, even though safety systems report faults

Common Causes

• Loss of power feed to the lateral acceleration sensor module: A blown fuse, open feed, or failing relay removes operating voltage so the module drops off the network.
• High-resistance module ground (loose bolt, corrosion, paint under eyelet): The module may power up but reset under load, which looks like a communication loss.
• Open circuit in CAN High or CAN Low between the module and the network: The rest of the vehicle can’t receive messages from that module, so other controllers set U0124.
• Short to power or short to ground on CAN High/CAN Low: The short clamps bus voltage and disrupts network traffic, which can knock multiple modules offline.
• Poor connector fit at the sensor/module (spread terminals, water intrusion): Intermittent contact creates dropouts, so U0124 may appear as pending or history.
• Harness damage near the module mounting area: rails, carpet edges, underbody debris, or prior collision work can pinch CAN wiring and cause intermittent opens.
• Network-wide issue mistaken as a single-module loss: A different module or a gateway fault can drag the bus down, and U0124 becomes a “victim” code.
• Module internal reset or failure: Internal power supply faults can stop message transmission, but you must prove good power, ground, and bus integrity first.

Diagnosis Steps

Use a scan tool that can run a full network scan and view U-code status. Have a DVOM with min/max, back-probes, and a low-amp clamp if available. A wiring diagram is required to identify the module’s power, ground, and CAN circuits. Plan to do voltage-drop tests under load, not continuity-only checks.

1. Confirm U0124 on a complete vehicle scan. Record whether it shows as pending, confirmed/stored, or history. Save freeze frame data and note ignition state, vehicle speed, and any related U-codes, ABS/ESC codes, or battery/voltage codes.
2. Run a network scan and check if the lateral acceleration sensor module appears as “online.” If the module does not report, treat this as a hard offline module or bus issue. If it reports but U0124 sits in another module, focus on intermittent dropouts and connector integrity.
3. Review freeze frame versus your own scan tool snapshot strategy. Freeze frame shows the exact conditions when U0124 set. Use a manual snapshot during a road test or wiggle test to catch intermittent communication loss as it happens.
4. Check power distribution first. Inspect the module-related fuses, ignition feeds, and any shared sensor/module supply circuits. Do not start probing at the module until you confirm the upstream fuse and feed path stay powered in the same key position shown in freeze frame.
5. Verify module power and ground with voltage-drop testing under load. With the circuit operating, load the circuit (key on, and if possible command the system awake). Measure voltage drop from battery negative to the module ground pin; target less than 0.1 V drop. Then measure from battery positive to the module power feed pin to catch high resistance on the supply side.
6. Inspect the module connector and harness routing in the area. Look for water tracks, green corrosion, bent pins, pushed-out terminals, and damaged seals. Pay attention to areas that flex, such as near movement, carpet edges, and recent interior or collision repairs.
7. Check CAN bus resistance with ignition OFF and the battery disconnected. Measure between CAN High and CAN Low at an accessible connector on the network, ideally near the suspected module. A healthy CAN bus typically reads about 60 ohms (two 120-ohm terminating resistors in parallel). Readings near 120 ohms or OL point to an open or missing termination, and a very low reading suggests a short.
8. Check CAN bias voltage with ignition ON. Measure CAN High to ground and CAN Low to ground at the module connector or a nearby network access point. Most CAN systems sit near 2.5 V on both lines at rest. Do not use ignition-off voltage readings as a reference because the bias only exists when the network is powered.
9. Isolate the fault if the bus readings look wrong. Disconnect the lateral acceleration sensor module and re-check bus resistance and bias voltage. If the network returns to normal with the module unplugged, suspect a shorted module or its connector. If the readings stay wrong, locate the short or open in the harness or another module on the same bus segment.
10. Prove the repair. Clear codes and run another full network scan. Road test under the same conditions noted in freeze frame and verify U0124 does not return as pending or confirmed. Recheck for related ABS/ESC or stability control codes because they often set when this module drops offline.

Professional tip: When U0124 appears with multiple “lost communication” codes, fix the bus problem first. A single shorted module or water-filled connector can take down the whole CAN segment. Always confirm power and ground with a voltage-drop test before condemning any module.

Possible Fixes

• Repair the module power feed fault, such as an open wire, poor splice, or blown fuse after you identify the root cause.
• Clean, tighten, and rework the module ground connection, then confirm less than 0.1 V drop under load.
• Repair CAN High/CAN Low wiring damage, including pinched sections, chafing, or corroded splices, and verify correct bus resistance afterward.
• Restore connector integrity by fixing terminal tension, replacing damaged pins, and correcting water intrusion sources.
• Replace the lateral acceleration sensor module only after you prove good power, ground, and a healthy network, and confirm the module still will not communicate.
• Correct a network-wide fault on the same bus segment, such as another module shorting the bus or a termination issue, when isolation testing points away from the lateral acceleration module.

Can I Still Drive With U0124?

You can often drive with a U0124 code, but you should treat it as a safety-system warning. Many vehicles use lateral acceleration input for stability control, traction control, and yaw control decisions. When the network loses that message, the vehicle may disable ESC/traction functions or run in a reduced strategy. Normal cruising usually feels fine, but the car can respond differently during hard braking, abrupt steering, slick roads, or evasive maneuvers. If the ABS, ESC, or traction lights stay on, avoid aggressive driving and poor weather until you repair the fault. If the vehicle shows multiple network U-codes, intermittent stalling, or the scan tool drops communication, stop driving and diagnose the network and power feeds first.

How Serious Is This Code?

U0124 ranges from an inconvenience to a real safety concern. It stays mostly inconvenient when the only issue is an intermittent communication drop and the car drives normally. It becomes serious when stability control, traction control, or ABS functions switch off or act unpredictably. That matters most on wet, icy, or gravel surfaces. Repeated communication loss can also point to a wider network problem, not just one sensor module. In that case, other modules can drop offline and create new faults. Don’t ignore U0124 if warning lamps stay on, if steering feels “odd” in corners, or if you see additional U-codes that suggest a bus-wide issue.

Common Misdiagnoses

Technicians often replace the lateral acceleration sensor module because the title names it, then the U0124 code returns. The more common miss involves skipping a full network scan and not checking whether the scan tool can talk to the suspected module. Another frequent mistake involves checking power and ground with a simple voltage reading, not a loaded voltage-drop test. A weak ground can pass a static test and fail under vibration. Some also chase wheel speed sensors or alignment problems because the ESC light comes on. U0124 indicates a communication loss, so you must prove the module went offline or the network could not carry its messages before condemning any sensor.

Most Likely Fix

The most common confirmed repair direction for U0124 involves restoring module power, ground, or connector integrity at the lateral acceleration sensor module. Corrosion, loose terminals, and water intrusion cause many repeat failures. The second common direction involves repairing the network wiring at a splice or connector that serves that module, especially after collision work or interior removal. After repairs, confirm the fix by driving under the enable conditions that previously triggered the code. Those conditions vary by vehicle, so use service information and recheck for pending codes after the road test.

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.