Network, generic

U0400 Invalid Data Received

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

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.

Likely causes

Modules on different software levels after a partial update
Replaced module not programmed or configured
Disturbed bus signal from poor connections or low supply voltage

Symptoms

  • Code cannot be cleared or returns at once
  • Functions of the storing module limited or warning lamp on, depending on the vehicle

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€50–600
Time0.3–2 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

can bus wiringcontrol module

Related codes

U0401U0402U0300U0073

References: saabwisonline.com, static.nhtsa.gov.