Toyota-specific code — factory diagnostic data| DTC Data Sheet | |
| Code | U0164 |
| Vehicle | 2014 Toyota Highlander (XU50) |
| System | Hybrid Control System |
| Fault type | Communication |
| Official meaning | Communication Error from A/C ECU to HV ECU |
| Source | 2014 Toyota Highlander factory diagnostic information |
Definition source: Toyota factory description. Diagnostic guidance is based on factory-defined fault logic for this code.
U0164 on the 2014 Toyota Highlander means: Communication Error from A/C ECU to HV ECU. It is a communication code reported by the Hybrid Control System.
Decode any Toyota Highlander VIN — free recalls, specs & safety ratings — free VIN decoder with NHTSA data
Looking for the cross-vehicle definition? Read the generic U0164 article for the SAE-defined fault logic that applies to all manufacturers.
U0164 Quick Answer
U0164 on a 2014 Toyota Highlander indicates Communication Error from A/C ECU to HV ECU. Start with a freeze-frame check and a careful inspection of the connector and wiring at the affected device before replacing any parts.
What Does U0164 Mean on a Toyota Highlander?
On the 2014 Toyota Highlander, the Hybrid Control System sets U0164 when it detects a fault matching its official definition: Communication Error from A/C ECU to HV ECU. This is a manufacturer-specific definition from Toyota factory diagnostic data and applies to the XU50-generation Highlander.
Symptoms
- Warning light for the affected system (check engine, ABS, airbag, or a system indicator depending on the module)
- Reduced or lost function of the hybrid control system
- Possible related codes from other modules on the Highlander CAN/LIN network
Common Causes
- Fault in the component named in the definition (communication error from a/c ecu to hv ecu)
- Open, shorted, or high-resistance wiring in the affected circuit
- Connector corrosion, water ingress, or a backed-out terminal
- Loss of supply voltage or a poor ground at the device
- Module internal fault — confirm wiring and supplies before condemning the module
Diagnostic Approach
For U0164 on the 2014 Toyota Highlander you’ll want a scan tool with Toyota-enhanced coverage (Techstream-class) — generic OBD-II readers usually will not read U-codes — plus a digital multimeter and the wiring diagram.
- Confirm the code is current, not stored history, and record freeze-frame data.
- Read all modules — related codes often pinpoint the root cause faster than the headline code.
- Inspect and wiggle-test the connector at the named device while watching live data.
- Measure supply voltage and ground integrity at the device; verify the circuit against the Highlander wiring diagram.
- Substitute or isolate the suspect device only after wiring and supplies check out.
- Clear the code and road-test through one or two drive cycles to confirm the repair.
Possible Fixes
- Repair open/short/high-resistance wiring or a corroded connector
- Restore supply voltage or ground at the affected device
- Replace the failed component named in the definition
- Replace and, where required, initialise/program the module if it is internally faulty
Can I Still Drive With U0164?
It depends on the system. Hybrid Control System faults that affect braking, the airbag/restraint system, power steering, or stability control should be repaired before further driving. Comfort or convenience faults can usually be deferred briefly, but related codes can mask one another on the Highlander network — diagnose promptly.
FAQ
Is U0164 specific to the Toyota Highlander?
The definition here is taken from 2014 Toyota Highlander (XU50) factory diagnostic data. The same code may appear on other Toyota models, but the affected module and exact criteria can differ between platforms.
Can I clear U0164 without fixing it?
You can clear it, but if the underlying fault is still present the Highlander will reset the code on the next drive cycle that runs the relevant monitor. Diagnose the cause first.
Will a generic OBD-II reader show U0164?
Often not — U-codes are manufacturer-specific and usually require a scan tool with Toyota-enhanced coverage such as a Techstream-class tool.
Source
Code definition from 2014 Toyota Highlander (XU50) factory diagnostic information (Hybrid Control System). Symptom, cause, and diagnosis guidance summarised from standard OBD-II diagnostic practice for this platform.