Fix U0164: Mechanic’s solutions that WORKED

The code U0164: Lost Communication with HVAC Control Module indicates a communication failure with the HVAC Control Module, which can affect the performance of the vehicle’s climate control system. It is a critical issue that should be addressed promptly to maintain comfort and functionality within the vehicle.

U0164 quick overview

Meaning	U0164: Lost Communication with HVAC Control Module
Is it serious?	Yes, it can be serious as it affects the communication with the Heating, Ventilation, and Air Conditioning (HVAC) system, potentially impacting climate control functions in the vehicle.
Possible causes	– Faulty or damaged HVAC Control Module – Wiring issues, such as frayed, corroded, or broken wires – Faulty connections or connectors in the CAN (Controller Area Network) bus – Grounding issues in the vehicle’s electrical system – Short circuits or open circuits in the CAN bus – Problems with other modules on the same communication network affecting the HVAC module
How to diagnose?	Scan for Codes: Use a diagnostic scanner to confirm the presence of U0164 and check for additional trouble codes. Inspect Wiring: Closely examine the wiring harnesses for damage, especially those connected to the HVAC module. Check Connectors: Inspect connectors for corrosion, looseness, or damage. Measure CAN Bus Voltages: Use a multimeter to verify proper voltages on the CAN bus lines. Test Ground Connections: Ensure all ground points are secure and free from corrosion. Isolate Modules: Disconnect other modules on the same network to identify if one is causing communication issues. Review Technical Bulletins: Look for manufacturer-specific technical service bulletins that may address known issues related to this code. Consult Documentation: Refer to the vehicle’s service manual for specific diagnostic procedures and module locations related to the HVAC system

How to fix U0164 – learn from mechanics

I looked into U0164 service cases at iatn.com website where in the private forums the mechanics seek advice from other mechanics. I looked up a bunch of cases to help you decide how to fix your issue and see what would a real mechanic do to solve it.

Case #1: Nissan

Vehicle Information

• 2009 Nissan Maxima S, 3.5L

Issue + Repair History

• Car towed in due to no start, key not recognized
• Code P0741 initially diagnosed
• Replaced steering wheel lock module
• Unable to register the intellikey, vehicle still won’t start

Other OBD2 Codes + Test Results

• U0164 – canbus failure
• P0741 – Torque Converter Clutch

Suggestions to Fix Issue

• Check with mobile locksmiths for possible solutions or tooling required
• Use Autel scan tool for key registration process
• Verify steering lock solenoid is under warranty extension
• Try using the spare key with the existing lock module
• Check “push start” fuse in engine compartment fuse box
• Examine communication lines between key slot, BCM, and ECM

Final Fix

• Fixed by replacing a fuse related to the HVAC module (U0164 CAN bus code)
• Vehicle started inadvertently on the fifth key press after being in anti-theft lockdown mode
• Cleared codes, and the vehicle operates normally now

Case #2: Chevrolet

Vehicle Information

• 2008 Chevrolet Tahoe LT, 5.3L

Issue + Repair History

• Vehicle involved in a front-end wreck
• ABS light, Traction light, Brake light all on
• Codes: U0140, U0151, U0159, U0164, U0168, U0214, U0109

Other OBD2 Codes + Test Results

• U0140 – Lost Communication With Body Control Module
• U0151 – Lost Communication With Restraints Control Module
• U0159 – Lost Communication With Parking Assist Control Module
• U0164 – Lost Communication With HVAC Control Module
• U0168 – Lost Communication With Vehicle Security Control Module
• U0214 – Lost Communication With Remote Function Actuation
• U0109 – Lost Communication With Fuel Pump Control Module
• Continuity tests pass, but issues with locating yellow and yellow/black wire connection to DLC

Suggestions to Fix Issue

• Scan all modules to identify affected ones
• Verify data lines’ ability to carry a load
• Check harness chafing at the body mounts along the left frame rail
• Inspect the DLC wiring harness for shorting on the adjustable pedal motor

Final Fix

• Removed an aftermarket navigation system
• Found communication wires cut
• After looping the cut wires, the vehicle’s issues were resolved

Case #3: Dodge

Vehicle Information

• 2008 Dodge Charger R/T, 5.7L

Issue + Repair History

• Police car experiencing no crank, no signal to starter relay, ASD, or ECM
• Loses communication with ECM/PCM during no start state
• Tried pulling IOD fuse, disconnecting battery, and letting it sit
• New battery installed, factory reflash wireless ignition mode for police package, multiple keys used

Other OBD2 Codes + Test Results

• U0100 – Lost Communication with ECM
• U0164 – Lost Communication with HVAC Module
• U1197 – Security Seed Response Not Received

Suggestions to Fix Issue

• Replace ignition switch and perform PCM reflash
• Check for intermittent ground in ECM harness
• Try jumping out the starter relay to check if it cranks
• Check WIM (Wireless Interface Module) and ESIM (Electronic Shift Module) communication
• Perform capacitor discharge by touching negative and positive battery cables together

Final Fix

• Replaced the ECM, which resolved the issue

Case #4: Land Rover

Vehicle Information

• 2007 Land Rover LR3 SE, 4.4L

Issue + Repair History

• Multiple warning lights: ABS, HDC, Ride Control
• Suspension lowering on speeds above 30mph
• Found water ingress from windshield seal
• Replaced transfer case module and cleaned mildly corroded connectors

Other OBD2 Codes + Test Results

• U0416 – Invalid data from Vehicle Dynamics Control Module
• U0010 – Medium speed can bus off
• U0164 – Bus signal missing from HVAC module
• U0421 – Invalid data from ride level control module

Suggestions to Fix Issue

• Check ABS module communication
• Inspect ABS connector for corrosion
• Verify all unsealed splices under right front sill plate
• Check CAN voltages and resistance
• Scope CAN hi and lo, disconnect modules one by one to find faulty one
• Check for codes in rear differential control module
• Inspect sunroof drains and joints in harness loom for water damage

Final Fix

• Found water ingress caused by defective windshield seal
• Repaired two corroded connectors and checked grounds
• Found no water in the interior fusebox (junction box)
• Replaced rear brake light bulbs and cleaned brake light switch
• Checked resistance on high-speed CAN bus
• Repaired a couple of corroded connectors under passenger front cabin
• Disassembled all-terrain module with no moisture or corrosion found
• Resolved with checking and repairing wiring issues related to water ingress

Case #5: Chevrolet

Vehicle Information

• 2007 Chevrolet Silverado 2500 HD LT, 6.0L

Issue + Repair History

• Truck often won’t crank, with no signal to crank relay
• When it does start, Instrument Panel Cluster (IPC) is dead, no communication with IPC, ABS, Radio, theft module, or HVAC
• BCM communicates but shows codes U0164, U0198, and U0155 (loss of communication codes)
• New AC Delco battery installed

Other OBD2 Codes + Test Results

• P0615 (start enable circuit)

Suggestions to Fix Issue

• Check grounds near OBD connector and secondary ground on driver side engine mount
• Check bus lines for resistance and ohms
• Inspect wiring harness at splice pack JX221 near the left kick panel
• Check Keyless entry/TPMS module if mounted on the floor
• Look for brake fluid on the ECBM connector
• Check the big round connector on the transmission for broken wires

Final Fix

• Disconnected one wire at a time at bus junction near parking brake pedal, regained communication
• Found bus line to On-Star module shorted behind dash or On-Star module failed internally
• Customer opted to leave On-Star module off the circuit, resolving the issue