U0164
Lost Communication With HVAC Control Module
- Severity
- Low
- Driving
- No driving restriction
The control module has stopped receiving messages from the HVAC (heating and air conditioning) control module. Heating, ventilation or air conditioning will not respond, and the system usually falls back to a fixed default setting. Nothing about the way the car drives is affected.
Possible causes
- CommonLow battery voltage or a discharged battery, dropping modules off the bus
- CommonBlown fuse or corroded earth on the supply to the HVAC (heating and air conditioning) control module
- CommonCorroded or water-ingressed connector - blocked drains soak footwell electrics
- PossibleDamaged, chafed or corroded bus wiring
- PossibleFailed module
- PossibleConnector disturbed during dashboard or heater work
What you might notice
- Climate control unresponsive or stuck on one setting
- Blower not working, or running at one fixed speed
- Temperature not adjustable
- Display blank
- Heated steering wheel inoperative
What to check, in order
- Check battery voltage and state of charge before anything else. A weak or failing battery drops modules off the bus and sets lost-communication codes with no wiring fault at all - this is the single most common false lead in this whole family.
- Check the fuses and earths for the HVAC (heating and air conditioning) control module.
- Look for water ingress. Blocked bulkhead and sunroof drains soak the footwell, and climate modules are often mounted right there.
- Ask whether the dashboard or heater has been worked on recently. A partially seated connector is a common cause.
- Note how many U-codes are stored. Several at once points at battery, earth or bus wiring.
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
Network communication
U0100U0101U0102U0103U0104U0105U0106U0107U0108U0109U0110U0111U0112U0113U0114U0115U0116U0117U0118U0119U0120U0121U0122U0123U0124U0125U0126U0127U0128U0129U0130U0131U0132U0133U0134U0135U0136U0137U0138U0139U0140U0141U0142U0143U0144U0145U0146U0147U0148U0149U0150U0151U0152U0153U0154U0155U0156U0157U0158U0159U0160U0161U0162U0163U0164U0165U0166U0167U0168U0169U0170U0171U0172U0173U0174U0175U0176U0177U0178U0179U0180U0181U0182U0183U0184U0185U0186U0187U0188U0189U0190U0191U0192U0193U0194U0195U0196U0197U0198U0199