OBD-II trouble code
U0440: Invalid Data Received From Pedestrian Alert Control Module
A module is receiving messages from the pedestrian alert control module, but the data inside them is implausible or out of range. The link is alive; the content is wrong. Affects the low-speed warning sound on hybrids and EVs, not core driving.
Quick facts
- System
- Network
- Category
- Network Communication
- Severity
- Low severity
- Drivable
- Usually safe to drive short-term
- Repair cost range
- $100 – $800
- DIY difficulty
- Shop recommended
What does U0440 mean?
Hybrids and electric vehicles are nearly silent at low speed, so regulations in the United States and many other markets require them to emit an artificial warning sound — the Acoustic Vehicle Alerting System (AVAS), sometimes called a pedestrian alert or approaching-vehicle audible system. The pedestrian alert control module generates that sound and adjusts its pitch and volume based on vehicle speed and direction, broadcasting its status onto the vehicle network. U0440 sets when a receiving module is still hearing from the pedestrian alert control module, but the data in its messages is invalid: a value is out of range, implausible, or contradicts what other modules see. The link is alive; the content can't be trusted. That is the key difference from a lost-communication code, which means the module has gone completely silent.
Because the fault is bad data rather than a dead bus, the causes cluster around whatever makes the module report wrong information. Low system voltage or a poor ground, moisture or corrosion at the module's connector, chafed wiring, or a failing external speaker/actuator can push the module into reporting an implausible value. The module is often mounted low near the front of the vehicle where its speaker projects sound forward, so it is exposed to road spray and debris — water intrusion is a realistic cause. Software that is outdated or was never re-flashed after a replacement can also trigger the code.
This is a low-severity, comfort-and-safety-feature code rather than a driveability fault. Core engine, brake, steering, and battery control do not depend on the pedestrian alert module, so the vehicle drives normally. The practical consequence is that the low-speed warning sound may be reduced, distorted, or absent, which matters for pedestrian safety in parking lots and at crosswalks even though it doesn't affect how the car moves. Some vehicles will show a message that the alert system needs service. Because U0440 is often secondary, read the full list — a companion voltage or component code often names the real cause, and low voltage is worth ruling out first.
Common causes
- Low system voltage, a weak battery, or a poor ground
- Water intrusion or corrosion at the module's forward, low-mounted connector
- Failing external warning speaker/actuator feeding the module a bad status
- Chafed or damaged wiring corrupting messages in transit
- Outdated, corrupted, or mismatched module software
- Pedestrian alert module replaced without proper programming
- Electrical noise on the bus corrupting messages
- Internal module fault
Symptoms
- Check engine light or a vehicle-service message
- Low-speed pedestrian warning sound reduced, distorted, or absent
- Message that the acoustic alert / AVAS system needs service
- No effect on how the vehicle drives
- Companion voltage or component codes stored alongside U0440
Diagnostic steps
- 1.Read ALL stored codes first — U0440 is often secondary to a voltage or component code that names the real fault.
- 2.Load-test the battery and check charging voltage and grounds; low voltage is a leading trigger.
- 3.Inspect the module and its speaker connector — mounted low and forward — for water intrusion, corrosion, and loose pins.
- 4.Confirm whether the warning sound is actually present at low speed as a functional check.
- 5.Check the external warning speaker/actuator and its wiring for damage.
- 6.Verify the module has the correct, current calibration, then address companion codes before replacing the module.
Repair cost
$100 – $800
Cost depends on what is producing the bad data. Correcting low voltage or a bad ground is often $150-$400. Repairing a corroded connector or water intrusion varies with access. An external warning speaker is typically $100-$300 installed. A module reflash is $100-$200, and pedestrian alert control module replacement with programming is the higher end at $300-$800. Because this is a low-severity feature code, thorough diagnosis usually finds a cheaper cause than a module swap.
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
Leave this one to a qualified shop. It typically involves emissions-critical components, refrigerant handling, or other work that requires manufacturer-grade tooling, training, or certification. DIY attempts often produce a more expensive problem than the original code.