C2126 Toyota Avalon – Transmitter ID not Received in Main Mode

Toyota logoToyota-specific code — factory diagnostic data
DTC Data Sheet
CodeC2126
Vehicle2014 Toyota Avalon (XX40)
SystemTire Pressure Warning ECU And Receiver
Fault typeFault
Official meaningTransmitter ID not Received in Main Mode
Source2014 Toyota Avalon factory diagnostic information

Definition source: Toyota factory description. Diagnostic guidance is based on factory-defined fault logic for this code.

C2126 on the 2014 Toyota Avalon means: Transmitter ID not Received in Main Mode. It is a fault code reported by the Tire Pressure Warning ECU And Receiver.

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⚠ Scan tool requirement: This is a Toyota-specific code. A generic OBD2 reader will retrieve the code but cannot access the module-level data, live PIDs, or bi-directional tests needed for diagnosis. A professional-grade scan tool with Toyota coverage is required for complete diagnosis.

C2126 Quick Answer

C2126 on a 2014 Toyota Avalon indicates Transmitter ID not Received in Main Mode. 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 C2126 Mean on a Toyota Avalon?

On the 2014 Toyota Avalon, the Tire Pressure Warning ECU And Receiver sets C2126 when it detects a fault matching its official definition: Transmitter ID not Received in Main Mode. This is a manufacturer-specific definition from Toyota factory diagnostic data and applies to the XX40-generation Avalon.

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 tire pressure warning ecu and receiver
  • Possible related codes from other modules on the Avalon CAN/LIN network

Common Causes

  • Fault in the component named in the definition (transmitter id not received in main mode)
  • 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 C2126 on the 2014 Toyota Avalon you’ll want a scan tool with Toyota-enhanced coverage (Techstream-class) — generic OBD-II readers usually will not read C-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 Avalon 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 C2126?

It depends on the system. Tire Pressure Warning ECU And Receiver 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 Avalon network — diagnose promptly.

Compare nearby Toyota transmitter received trouble codes with similar definitions, fault patterns, and diagnostic paths.

  • C1278 – Toyota Avalon – Abnormal Change in Output Signal of Rear Speed Sensor LH (Test Mode DTC)
  • C1311 – Toyota Avalon – Open in Main Relay 1 Circuit
  • C1312 – Toyota Avalon – Short in Main Relay 1 Circuit
  • C1281 – Toyota Avalon – Master Cylinder Pressure Sensor Output Malfunction (Test Mode DTC)

FAQ

Is C2126 specific to the Toyota Avalon?

The definition here is taken from 2014 Toyota Avalon (XX40) 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 C2126 without fixing it?

You can clear it, but if the underlying fault is still present the Avalon 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 C2126?

Often not — C-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 Avalon (XX40) factory diagnostic information (Tire Pressure Warning ECU And Receiver). Symptom, cause, and diagnosis guidance summarised from standard OBD-II diagnostic practice for this platform.