U0424
Invalid Data Received From HVAC Control Module
Communication network
Generic OBD-II
Low
What it means
U0424 is a network communication code: a module is receiving data from the HVAC (heating, ventilation, and air-conditioning) control module that is corrupt, missing, or out of range. Communication is working, but the values are wrong. It affects the climate system only — engine and safety systems are unaffected — so the main symptom is climate control not working the way it should.
Low
Can I keep driving? Safe to drive — this affects climate control, not engine or safety systems; heating, A/C, or defog may not work correctly.
Common symptoms
What you'll notice
- Climate control behaving erratically or not responding
- Wrong temperature, fan speed, or airflow-mode output
- HVAC display or controls blank or frozen
- Automatic climate features not adjusting as expected
Common causes
Most likely first
- Internal fault in the HVAC control module sending corrupt dataLikely
- Wiring or connector problems on the bus to the HVAC moduleCommon
- Low system voltage or a poor ground at the moduleCommon
- Failed HVAC sensor (in-car temperature, blend-door, etc.) feeding bad valuesLess often
How to diagnose & fix
Work through it in order
- Scan all modules and note freeze-frame data; clear any lost-communication codes first.
- Check battery voltage and the HVAC module's ground.
- Inspect the module connector and bus wiring for corrosion or loose pins.
- Test HVAC sensors and actuators for range faults.
- If wiring, power, and sensors are good, suspect the HVAC control module and confirm with manufacturer tests.
FAQ
Quick answers
Is it safe to drive with U0424?+
Yes. It only affects the climate system. The main inconvenience is heating, A/C, or defog not working properly — clear defog before cold or wet weather driving.
Can I just clear U0424?+
It returns while the module reports bad data. Check power and wiring, then the HVAC module, rather than just clearing.
Related codes
Often seen with U0424
Read & clear U0424 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