U0325
Software Incompatibility With Auxiliary Heater Control Module
Network / communication
Generic OBD-II
Low
What it means
U0325 means the auxiliary (supplemental cabin) heater control module is running software that doesn't match the rest of the network — typically after a module swap or an incomplete update. The result is a heater that may not work, but the engine and safety systems are unaffected, so the vehicle is safe to drive.
Low
Can I keep driving? Yes — only the auxiliary/cabin heater function is affected; the powertrain and safety systems keep working normally.
Common symptoms
What you'll notice
- Check-engine or module warning light on
- Auxiliary or supplemental cabin heater not working
- Slow cabin warm-up in cold weather
- Other modules log lost-communication codes for the auxiliary heater module
Common causes
Most likely first
- Auxiliary heater control module software doesn't match the network software levelLikely
- Replacement or used heater module installed without correct programmingCommon
- Interrupted or incomplete software update on the heater moduleCommon
- Coding data out of sync after another module was reflashedLess often
How to diagnose & fix
Work through it in order
- Scan all modules and identify the mismatched software/part numbers.
- Confirm the auxiliary heater module part number is correct for this VIN.
- Reflash or recode the module to the manufacturer-approved software level.
- If the module was recently replaced, program it to the vehicle, then clear and re-test.
FAQ
Quick answers
Is it safe to drive with U0325?+
Yes. This affects only the auxiliary cabin heater. The engine, brakes, and steering are unaffected — you may just get slower heat in cold weather.
Can I just clear U0325?+
It will come back until the software mismatch is corrected. The heater module needs to be reprogrammed to the right level.
Related codes
Often seen with U0325
Read & clear U0325 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