U0325
Software Incompatibility with Auxiliary Heater Control Module
- Severity
- Low
- Driving
- No driving restriction
The software in the auxiliary heater control module is not compatible with the rest of the vehicle. Heating, ventilation or air conditioning will not respond correctly, and the system usually falls back to a fixed default. Nothing about the way the car drives is affected.
Possible causes
- CommonThe auxiliary heater control module replaced but never coded to this vehicle
- CommonUsed module fitted from a different vehicle or trim level
- CommonOption coding not written after fitting - climate zones, heated seats, auxiliary heater
- CommonSoftware update interrupted during programming
- CommonWrong part number - single-zone and multi-zone modules differ
What you might notice
- Climate control unresponsive or stuck on one setting
- Temperature not adjustable
- Rear or multi-zone controls not working
- Display blank or in the wrong language
- Fault present since a repair
What to check, in order
- Ask what was done. A module or dashboard repair immediately before this appeared is the explanation.
- Check the option coding matches the car's actual climate equipment - the number of zones in particular.
- Check the part number against the trim level.
- One exception to this being comfort-only: on many vehicles the same module runs the windscreen demister and the air conditioning compressor that dries the air. If you cannot clear a misted or frozen screen, that is a visibility problem worth fixing before winter driving.
- This needs manufacturer-level coding rather than a replacement part.
Read this code from your own car
Plug an ELM327 adapter into the OBD-II port under the dashboard. Pin16 reads every stored, pending and permanent code, explains each one like this page does — offline, with no account — and shows what the car recorded when the fault was set.
Where this code sits
U00xxU01xxU02xxU03xxU04xxU05xxU06xxU07xxU08xxU09xxU0AxxU0BxxU0CxxU0DxxU0ExxU0FxxU10xxU11xxU12xxU13xxU14xxU15xxU16xxU17xxU18xxU19xxU1AxxU1BxxU1CxxU1DxxU1ExxU1FxxU20xxU21xxU22xxU23xxU24xxU25xxU26xxU27xxU28xxU29xxU2AxxU2BxxU2CxxU2DxxU2ExxU2FxxU30xxU31xxU32xxU33xxU34xxU35xxU36xxU37xxU38xxU39xxU3AxxU3BxxU3CxxU3DxxU3ExxU3Fxx