U0404 low

Invalid Data Received From HVAC Control Module

The U0404 code means the vehicle's onboard diagnostic system has detected: Invalid Data Received From HVAC Control Module. This is a low severity code.

My Garage →
Keep driving?
Yes, but fix soon
DIY difficulty
moderate
Estimated cost
$100 - $500 (parts and labor)
Diagnose CAN Bus Issues
LAUNCH CRP123X Full System Scanner

Network codes mean modules are not communicating. You need a scanner that reads all systems to find the problem.

Check Price on Amazon

Affiliate link -- we earn a commission at no extra cost to you.

Common Symptoms

  • Climate control not maintaining set temperature
  • Air blowing from wrong vents
  • Temperature display showing incorrect readings
  • Automatic climate mode not working correctly
  • Blower speed changing unexpectedly

Probable Causes (Ranked by Likelihood)

  • HVAC control module sending incorrect sensor data Very High
  • Failed interior temperature sensor High
  • Blend door actuator sending wrong position data Moderate
  • Wiring issue between HVAC module and BCM Low

Step-by-Step Diagnostic Procedure

  1. Check interior temperature sensor readings with a scan tool

  2. Verify blend door actuator positions match commanded positions

  3. Inspect wiring to the HVAC module and temperature sensors

  4. Check the ambient temperature sensor for accurate readings

  5. Monitor HVAC live data for erratic or impossible values

Frequently Asked Questions

Can I drive with code U0404?

Yes, safe to drive. The climate control may not maintain the correct temperature but no driving systems are affected.

What causes U0404?

Usually a failed temperature sensor or blend door actuator sending incorrect data to the HVAC module. These sensors can degrade over time.

Is U0404 expensive to fix?

Typically $100 to $500. Temperature sensor replacement is inexpensive. Blend door actuator replacement can be more costly due to dashboard disassembly.

Sources

This page is built from documented references. Verify against your own service info before repair work.

Explore More

Search codes Vehicle-specific fixes Guides By make

Was this helpful?

Share carcodefinder.com with a friend who needs to decode their check engine light.

Browse by symptom → Read repair guides → Fixes by vehicle →