LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Toyota >> 2009 >> Prius Base >> Repair and Diagnosis (Single Page) >> Accessories & Equipment >> Warning Systems >> Tire And Wheel >> Tire Pressure Warning System >> DTC C2121/21: No Signal from Transmitter ID1 in Main Mode; DTC C2122/22: No Signal from Transmitter ID2 in Main Mode; DTC C2123/23: No Signal from Transmitter ID3 in Main Mode; DTC C2124/24: No Signal from Transmitter ID4 in Main Mode; DTC C2181/81: Transmitter ID1 not Received (Test Mode DTC); DTC C2182/82: Transmitter ID2 not Received (Test Mode DTC); DTC C2183/83: Transmitter ID3 not Received (Test Mode DTC); DTC C2184/84: Transmitter ID4 not Received (Test Mode DTC) >> Description
April 5, 2026: LEMON Manuals is launched! Read the announcement.

DTC C2121/21: No Signal from Transmitter ID1 in Main Mode; DTC C2122/22: No Signal from Transmitter ID2 in Main Mode; DTC C2123/23: No Signal from Transmitter ID3 in Main Mode; DTC C2124/24: No Signal from Transmitter ID4 in Main Mode; DTC C2181/81: Transmitter ID1 not Received (Test Mode DTC); DTC C2182/82: Transmitter ID2 not Received (Test Mode DTC); DTC C2183/83: Transmitter ID3 not Received (Test Mode DTC); DTC C2184/84: Transmitter ID4 not Received (Test Mode DTC): Description

The tire pressure warning valve and transmitters installed in the tire and wheel assemblies measure the air pressure of the tires. The measured values are transmitted to the tire pressure warning antenna and receiver on the body as radio waves and then sent to the tire pressure warning ECU. The ECU compares the measured air pressure values with the air pressure threshold. When the measured air pressure value is less than this threshold, the warning light in the combination meter illuminates.

The tire pressure warning valve and transmitters constantly send radio waves to the tire pressure warning antenna and receiver.

Under the conditions below, the tire pressure warning antenna and receiver is unable to receive the signals from the tire pressure warning valves and transmitters, and a DTC is stored.

HINT:

These DTCs are detected when no signals are received for 20 minutes or more, after a vehicle speed of 8 km/h (5 mph) or more is detected and no signals are still received for 20 minutes or more.

DTCs from C2121/21 to C2124/24 can only be cleared by using Techstream. DTCs from C2181/81 to C2184/84 can be cleared when the transmitter in the tire pressure warning valve and transmitter sends a forced transmission signal or test mode ends. DTCs from C2181/81 to C2184/84 are output only in test mode.

DTC DETECTION CONDITION CHART

DTC Code DTC Detection Condition Trouble Area
C2121/21
C2122/22
C2123/23
C2124/24
When all conditions below are met:
  • Tire pressure warning valve and transmitter is not in stop mode
  • Signal is not received from tire pressure warning valve and transmitter for 20 minutes or more
  • Vehicle speed is more than 8 km/h (5 mph) for a total of 20 minutes
  • Tire pressure warning valve and transmitter
  • Tire pressure warning antenna and receiver
  • Harness or connector
  • Tire pressure warning ECU
C2181/81
C2182/82
C2183/83
C2184/84
Test mode procedure is performed.
  • Tire pressure warning valve and transmitter
  • Tire pressure warning antenna and receiver
  • Harness or connector
  • Tire pressure warning ECU

HINT:

It is necessary to perform this procedure in order to identify the malfunctioning tire pressure warning valve and transmitter because it cannot be identified by only the output DTCs.