U0164 Code: Lost Communication with HVAC Module — Causes & Fix
U0164 means lost communication with the HVAC (climate control) module — the network can no longer talk to the heating/AC controller.
- Applies to
- All OBD-II vehicles (any make or model)
- Est. repair cost
- $50 – $700
- Time to fix
- 1–4 hours
What it means
Causes include HVAC module power/ground loss, CAN wiring faults, or a failed module. U0164 is a generic OBD-II network/communication ("U") code defined in the SAE J2012 standard, so it applies to virtually any modern OBD-II vehicle regardless of make. These faults usually point to the vehicle's data bus (often CAN) or a module that has dropped off the network. Fix the wiring/module fault, then clear the code with a scan tool.
Symptoms
- Climate control not responding
- Warning light
- AC/heater controls dead or erratic
How to fix it
- 1
Check HVAC module power and wiring
1. Verify the HVAC module power and grounds. 2. Inspect the CAN wiring.
- 2
Diagnose the module
1. Scan whether the HVAC module responds. 2. Repair wiring or address the module, then clear the code.
Frequently asked questions
Is U0164 serious?
It mainly affects climate control, so it is low risk to drive with — but the AC/heater may not respond until the module communication is restored.
Last updated July 19, 2026
Guidance only — always consult a qualified professional or the official service manual before carrying out repairs.