U0401 fault code: what it means

U0401: Invalid data received from the engine computer: modules are getting messages from the ECM that make no sense.

Network (communication between modules) · Minor

Usual causes, most likely first

engine fault codes stored in the ECM
ECM software mismatch
CAN wiring fault

U0401 by make

Jeep

Implausible data received from engine computer, logged by the 9-speed TCM (Cherokee/Renegade). TCM reflash usually clears it.

Usual causes: TCM software; engine fault affecting torque signal; CAN fault

What the repair usually costs

Diagnostic scan, fault code read and report (warning light on)NZ$70–NZ$140 · A$80–A$150

Not sure what U0401 means on your car? Ask Credov.

Before you clear it

Write the code down or photograph the scanner first. A code that comes straight back after clearing points to a fault that is still there. A car whose codes were cleared just before you arrived may be hiding one: the scanner's readiness monitors show "not ready" for a while after codes are cleared.

Researched by Credov from manufacturer and workshop sources. A fault code points to where a fault may be; a workshop confirms it with a diagnosis. Browse all fault codes.