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ElectricalSeverity High: diagnose before driving on

U0164Lost Communication With HVAC Control Module

What it means

A control module stopped receiving messages from the climate control module on the data bus (CAN). The climate control module may be without power or ground, or the bus wiring to it is faulty.

Symptoms

  • Heating or air conditioning controls not working
  • Several warning lights at once
  • Other modules may store related codes

Common causes

  • No power or ground at the climate control module
  • CAN wiring open, shorted or corroded (CAN-H / CAN-L)
  • Low battery voltage during cranking
  • Failed climate control module

What to check first

  1. Check fuses, supplies and grounds at the climate control module
  2. Measure CAN-H to CAN-L resistance with the battery disconnected (about 60 Ω on most cars)
  3. Scope CAN-H and CAN-L for a clean mirrored signal
Can I drive with U0164? Not recommended. U0164 can lead to stalling, limp mode or engine damage; diagnose it before driving further.

Generic OBD-II meaning. Manufacturer-specific meanings and checks can differ; always check the service information for the car.

How to test the parts behind U0164

CAN bus networkWiring, typical values, multimeter and scope tests

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U0164: questions and answers

What does U0164 mean?

U0164: Lost Communication With HVAC Control Module. A control module stopped receiving messages from the climate control module on the data bus (CAN). The climate control module may be without power or ground, or the bus wiring to it is faulty.

What are the symptoms of U0164?

Heating or air conditioning controls not working. Several warning lights at once. Other modules may store related codes.

What causes U0164?

No power or ground at the climate control module. CAN wiring open, shorted or corroded (CAN-H / CAN-L). Low battery voltage during cranking. Failed climate control module.

How do you diagnose U0164?

1. Check fuses, supplies and grounds at the climate control module 2. Measure CAN-H to CAN-L resistance with the battery disconnected (about 60 Ω on most cars) 3. Scope CAN-H and CAN-L for a clean mirrored signal

Can I drive with U0164?

Not recommended. U0164 can lead to stalling, limp mode or engine damage; diagnose it before driving further.