U0404
Invalid Data Received From Gear Shift Control Module A
Network / communication
Generic OBD-II
Medium
What it means
U0404 means a module is receiving data from gear shift control module A that is out of range or implausible. On shift-by-wire vehicles this governs gear selection, so the transmission may drop into limp mode or refuse to change gears. You can usually limp a short distance, but have the module's wiring, shifter sensor, and software checked before driving far.
Medium
Can I keep driving? Short trips only — on shift-by-wire vehicles, invalid gear-selection data can force limp mode or prevent gear changes; get it diagnosed before driving far.
Common symptoms
What you'll notice
- Transmission or gear-selector warning light on
- Gear position mismatched, missing, or not selectable (shift-by-wire)
- Transmission stuck in a fixed gear or limp mode
- Other modules storing 'lost communication' or 'invalid data' codes for the gear shift module
Common causes
Most likely first
- Gear shift control module broadcasting out-of-range or implausible values onto the busLikely
- Internal gear shift module fault or corrupted softwareCommon
- Wiring, connector, or ground fault at the module corrupting bus dataCommon
- Shifter position sensor feeding the module impossible readingsLess often
How to diagnose & fix
Work through it in order
- Scan all modules and record every stored code, including companion communication codes.
- Check gear shift module power, grounds, and connectors.
- Inspect the shifter and module wiring for damage or corrosion.
- Verify module software; reflash or replace and program if internally failed, then clear and re-test.
FAQ
Quick answers
Is it safe to drive with U0404?+
Only briefly. On shift-by-wire systems, bad gear-selection data can force limp mode or block gear changes, which can leave you unable to select a gear. Get it diagnosed before driving far.
Can I just clear U0404?+
It returns until the fault is repaired. The gear shift module is still reporting invalid data, so the wiring, sensor, or module problem must be fixed first.
Related codes
Often seen with U0404
Read & clear U0404 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX