U0401 — Invalid Data Received From ECM/PCM "A"
Category: Network / Communication Severity: High
Updated:
DTC code U0401 means: Invalid Data Received From ECM/PCM "A". It falls under the "Network / Communication" category, with an estimated severity of High. Common causes include engine ECU with an internal fault or its own stored codes, outdated or incompatible software and eCM power or ground problems; it's worth confirming the diagnosis before replacing parts.
Possible causes
- Engine ECU with an internal fault or its own stored codes
- Outdated or incompatible software
- ECM power or ground problems
- CAN bus interference
Symptoms
- Erratic shifting (automatic)
- ABS/stability lights
- Cruise control disabled
- Check engine light
How to diagnose it step by step
- Read the ECM codes.
- Fix those codes first.
- Check battery and grounds.
- Check for software updates.
How to fix it
Another module (TCM, ABS) is receiving bad data from the ECM. Read and fix the codes stored in the ECM itself first; also check battery and grounds, and look for software updates.
Estimated repair cost
Depends on the cause: $0 (warranty update) to $1,500 (ECU).
Frequently asked questions
What does DTC code U0401 mean?
Invalid Data Received From ECM/PCM "A".
Is code U0401 serious?
Severity High. Have it checked as soon as possible, especially if it affects safety or the catalytic converter.
Can I keep driving with code U0401?
Carefully until the engine codes are resolved.
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