U0164

Lost Communication With HVAC Control Module

Network / communication Generic OBD-II Low

What it means

U0164 means a controller has lost communication with the HVAC control module — the unit that runs the heating, ventilation, and air-conditioning system. When it drops off the network, climate controls stop responding and you may lose A/C, heat, or fan control, but the engine, brakes, and steering are unaffected. It is usually caused by a wiring or connector fault, a lost power or ground feed, or a failed module.

Low

Can I keep driving? Yes — this affects climate control only, so the car drives and stops normally; you may just lose automatic heating, A/C, or fan control until it's fixed.

Real-world scan data

Seen in

1,005

scans in the past year

Found in

0.2%

of scans

0.3%

of scans that found faults

Appears alongside · share of U0164 scans

U0100in 40.8% of scans

U0155in 35.4% of scans

U0121in 31.8% of scans

Figures reflect only diagnostic scans recorded through our own apps and tools. Cars are typically scanned because a symptom or warning light prompted it, so these counts describe our scan records — not the incidence of faults in any model, and not the quality, reliability, or safety of any vehicle. No comparison between manufacturers or models is implied. All trademarks belong to their respective owners; no affiliation or endorsement is implied.

Common symptoms

What you'll notice

Climate control unresponsive or stuck on one setting
No A/C, heat, fan-speed, or airflow control
HVAC display or buttons dead or frozen
The HVAC control module unresponsive to a scan tool

Common causes

Most likely first

Damaged, corroded, or disconnected wiring or connector at the HVAC moduleLikely
Lost power or ground feed to the moduleCommon
CAN bus fault between the HVAC module and the networkCommon
Failed HVAC control moduleLess often
Blown fuse feeding the climate control systemLess often

How to diagnose & fix

Work through it in order

Scan all modules and confirm whether the HVAC module responds at all.
Check the fuse, power, and ground feeding the HVAC control module.
Inspect the module's connector and wiring for corrosion or damage behind the dash.
Check the CAN circuits between the module and the gateway for opens or shorts.
If power and wiring are good but the module stays silent, replace it, then clear and re-test.

FAQ

Quick answers

Is it safe to drive with U0164?+

Yes — it only affects the climate control system, so the engine, brakes, and steering are unaffected; it's a comfort issue rather than a safety one.

Can I just clear U0164?+

You can, but if the module or its wiring is faulty the code and the dead climate controls return until the connection is repaired.

Read & clear U0164 yourself

Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.

▶ Get it on Google Play

✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX