U0400Invalid Data Received
- Generic OBD-II code · Network
- How the car detects it
- U0400 is the unspecific entry of the invalid-data block. It says that a module receives messages from another node on time but rejects their content, without naming the sender; the codes from U0401 upward name the partner. GM's 2011 Saab 9-5 manual handles U0400 to U05FF in one procedure: the receiver doubts the integrity of incoming data, the test runs between 9 and 16 V while the network works, no circuit check is involved, and if the code stands alone the named module is reprogrammed, then replaced. Harley-Davidson shows the usual trigger in bulletin M1720: on 2021-2024 Pan America models, updating only the ECM leaves a U040000 that cannot be cleared, so the BCM must be flashed first. Lost contact is the U01xx block, software conflicts are U03xx. Effects depend on the module that stores it.
- What you may notice
- Code cannot be cleared or returns at once
- Functions of the storing module limited or warning lamp on, depending on the vehicle
- Likely causes
- LikelyModules on different software levels after a partial update
- PossibleReplaced module not programmed or configured
- RareDisturbed bus signal from poor connections or low supply voltage
- Repair
- Workshop only · Usually a job for a workshop.Typical cost: €50 – €600
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.