U0164 Code: Fix communication error with HVAC control module


An OBD 2 scanner is attached to every vehicle to diagnose any problem you face as a car owner. The code U0164 is just like the trouble code you notice in that case. And this article mainly tells you the details about this code.

Meaning Of the Code U0164:

The trouble code U0164 is a generic communication process that is mainly a diagnostic trouble code that you notice from the OBD2 scanner vehicle in many models or versions. The trouble code I told you before means the HVAC control modules have some communication problems with other control modules and communicate with each other. The Controller Area Network or CAN bus system is the main thing to communicate with another control module with its circuit.

Without the help of the CAN bus, the control module can’t pass data between them, and with that, you also face problems with the problem scanner. For this reason, the scanner is also unable to determine where the trouble locates and which circuit is damaged.

Where is the HVAC control module Located?

To solve the trouble code, you must know where the HVAC control module is. The HVAC is located behind the dash in most vehicles, mainly in the vehicle’s center or behind the instrumental panel. It gets inputs from different sensors, some hardwire directly to it, and most data is sent with the help of the CAN bus system. This input data allows all the control modules in the vehicle’s internal temperature, and in this case, for front or both passengers of the car. The car manufacturer, type of communication system, number, and colors of wire for this communication system r are the steps of troubleshooting. If you don’t find the HVAC, you can get help from TSBs because it contains all details of your car with the solution to many problems. HVAC control module

Code severity and symptom:

The severity of this case is no issue with the module’s backup capabilities. If there is an issue with electrical, then the module needs a backup and defaults to the defrost position. But many times, the U0164 code also has some other symptoms, like:

  • Malfunction Indicator Light or MIL is “ON,”
  • The engine light is on.
  • Inoperative or power-up problem of the HVAC control module.

Reason For the trouble code U0164:

There are many reasons behind this trouble code. Like:

  • Open CAN bus circuit,
  • CAN bus circuit in any short to ground or ground,
  • Absence of power or ground to HVACCM,
  • Fault in the control module, which is a rare case.

Diagnostic and solving process of the trouble code U0164:

The quickest way to find the problem is to look at the Technical Service Bulletins or TSBs. Because these TSBs work like a manual book for every car. That’s why you get every detail from this manual book. Many people also face this type of problem, and these features contain solutions with the details of the trouble. The TSBs not only save your time but also save some money.U0164 Lost Communication With HVAC Control Module

  • DTC Checkup

Check the DTCs at the first step. These DTCs are mainly related to tire, VIN or vehicle identification number, or battery. So you need to check all things first. If you misdiagnose the problem, it will cost o more money with extra time. Try to diagnose the problem. It would help if you had a scan tool to find the problem from DTC, and this code quickly finds out with this. And then, try to access the HVAC, and when you get there, you can go through the memory code and find the problem is solved or still in there.

  • Power supply

The trouble is related to the common failure of loss of power or ground of the HVAC sometimes. So you also need to check the fuses supply of the HVAC of your car. After that, locate the ground and check if any poor or damaged wires are there. If you point out the problem, try to repair this by repairing the wire. It would help if you had a wire bristle brush and baking soda or water to clean the wire, then clean the wire and connector or where it connects. Then give time to dry the part you repair.u0164 chevy

After doing any repair, clear the code from memory and reprogramme the system. If you don’t find the problem, then it’s restored itself. If the code pops up again, the problem is connected to HVAC.

  • Check CAN BUS

After that, it’s time to check all the connectors of the HVAC, but make sure it’s turned off with the help of the manufacturer’s process. Then check the connection of the CAN bus system. This bus system mainly also connected all the modules of the vehicle. But first, disconnect the negative battery cable. Then visually inspect the connectors and wiring. Then look for the scratches, scuffs, exposed wires, melton plastic, or burn marks. Disconnect all the connectors and examine all the parts of the terminal. If you find the burnt or green tint compression, then clean the terminals. Use any electrical contact cleaner and also a plastic brush. And after that, dry the place and apply the electrical grease where the corrosion took place.

  • Measure the voltage

If you face the problem again, you need some voltage check before plugging in all the connectors with HVAC. It would help if you had a digital volt ohmmeter or DVOM. Then locate the RCM power and ground. The wiring diagram accesses and finds where the main power and ground are situated in the HVAC. Reconnect the HVAC with the battery. Connect the red wire with the voltmeter to the battery. Then the voltage of the power source with the HVAC and the black wire with the voltmeter to the ground. And then you can get the reading as a good reason. After that, connect the red wire from the voltmeter with the battery positive and black wire with each ground. Then again, you can see the battery voltage every time you plug the voltmeter into it. But before proceeding, check the wiring diagram and check both communication circuits in the HVAC.carry out the result you check related to your vehicle.

  • Check circuits

After that, check two communication circuits and find CAN C+ and CAN C- of the circuit. Then connect all the black voltmeter wire with the reliable ground and connect CAN C+ with red wire. When you notice the engine’s key, you get 2.6 volts with slight fluctuations. Then vice versa the connection, connecting the CAN C- with red wire then finding the output. You can get 2.4 volts with sight fluctuations. Like that, check the CAN B+ and CAN B- like before. Then you find 0.5 volts with a slight change in the CAN B+. After that, you also get 4.4 volts and small fluctuations in the side of the CAN B-.

When you go through all possible solutions but still end up with the problem in the car screen or are unable to remove the problem of U0164, you need an automotive technician’s help.

Repair cost:

 The repair cost varies with the type and model of the car. The price also differs from the place you go to fix the problem. But a professional needs around one hour to solve the problem. And I will also give you an idea about the budget. You need around 75$ to 100$ to repair the problem. When you first find the problem, try to fix the issue as soon as possible.


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