Invalid Data Received
What it means
U0400 is a generic network code meaning a module received data over the communication bus that was out of range or implausible, without naming a specific source module. What it means for you depends entirely on which signal went bad — anything from a single disabled feature to powertrain limp mode — so the first step is scanning for the companion codes that point to the real culprit.
Can I keep driving? Depends on the source — a module is reporting implausible data over the bus; effects range from a disabled feature to limp mode, so scan for companion codes first.
Real-world scan data
Figures reflect only diagnostic scans recorded through our own apps and tools. Cars are typically scanned because a symptom or warning light prompted it, so these counts describe our scan records — not the incidence of faults in any model, and not the quality, reliability, or safety of any vehicle. No comparison between manufacturers or models is implied. All trademarks belong to their respective owners; no affiliation or endorsement is implied.
Common symptoms
What you'll notice
- Check-engine or module warning light on
- Feature or system tied to the bad data not working correctly
- Reduced-power/limp mode if the invalid data affects the powertrain
- Companion 'invalid data' or 'lost communication' codes stored in other modules
Common causes
Most likely first
- A module transmitting out-of-range or implausible values onto the CAN busLikely
- Sensor feeding a module corrupted or impossible readingsCommon
- Wiring, connector, or ground fault corrupting bus dataCommon
- Software or configuration mismatch after a repair or module swapLess often
How to diagnose & fix
Work through it in order
- Scan every module and read all stored codes, including the companion codes, to find the source.
- Check freeze-frame data to see which signal was flagged invalid.
- Inspect the wiring, connectors, and grounds for the implicated module.
- Test the sending module and its sensor; reprogram or replace as needed, then clear and re-test.
FAQ
Quick answers
Is it safe to drive with U0400?+
Can I just clear U0400?+
Related codes
Read & clear U0400 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.