Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
2017 Subaru WRX BaseFACTORY OEM SERVICE PROCEDURE
Tire Pressure Monitor System (TPMS) DTCS
TIRE PRESSURE MONITOR SYSTEM (TPMS) DIAGNOSTIC TROUBLE CODE IDENTIFICATION
| DTC | Item | Contents of diagnosis | Remarks |
|---|---|---|---|
| C2021 | Tire 1 Air Pressure Low (Normal Mode) | Tire pressure of tire 1 is reduced. | <Ref. to DTC C2021 TIRE 1 AIR PRESSURE LOW (NORMAL MODE) , Diagnostic Procedure with Diagnostic Trouble Code (DTC).> |
| C2022 | Tire 2 Air Pressure Low (Normal Mode) | Tire pressure of tire 2 is reduced. | <Ref. to DTC C2022 TIRE 2 AIR PRESSURE LOW (NORMAL MODE) , Diagnostic Procedure with Diagnostic Trouble Code (DTC).> |
| C2023 | Tire 3 Air Pressure Low (Normal Mode) | Tire pressure of tire 3 is reduced. | <Ref. to DTC C2023 TIRE 3 AIR PRESSURE LOW (NORMAL MODE) , Diagnostic Procedure with Diagnostic Trouble Code (DTC).> |
| C2024 | Tire 4 Air Pressure Low (Normal Mode) | Tire pressure of tire 4 is reduced. | <Ref. to DTC C2024 TIRE 4 AIR PRESSURE LOW (NORMAL MODE) , Diagnostic Procedure with Diagnostic Trouble Code (DTC).> |
| C2121 | Transmitter 1 No Data | Data cannot be received from transmitter 1. | <Ref. to DTC C2121 TRANSMITTER 1 NO DATA , Diagnostic Procedure with Diagnostic Trouble Code (DTC).> |
| C2122 | Transmitter 2 No Data | Data cannot be received from transmitter 2. | <Ref. to DTC C2122 TRANSMITTER 2 NO DATA , Diagnostic Procedure with Diagnostic Trouble Code (DTC).> |
| C2123 | Transmitter 3 No Data | Data cannot be received from transmitter 3. | <Ref. to DTC C2123 TRANSMITTER 3 NO DATA , Diagnostic Procedure with Diagnostic Trouble Code (DTC).> |
| C2124 | Transmitter 4 No Data | Data cannot be received from transmitter 4. | <Ref. to DTC C2124 TRANSMITTER 4 NO DATA , Diagnostic Procedure with Diagnostic Trouble Code (DTC).> |
| C2221 | Transmitter 1 Pressure Data Abnormal | Transmitter 1 data contents are abnormal. | <Ref. to DTC C2221 TRANSMITTER 1 PRESSURE DATA ABNORMAL , Diagnostic Procedure with Diagnostic Trouble Code (DTC).> |
| C2222 | Transmitter 2 Pressure Data Abnormal | Transmitter 2 data contents are abnormal. | <Ref. to DTC C2222 TRANSMITTER 2 PRESSURE DATA ABNORMAL , Diagnostic Procedure with Diagnostic Trouble Code (DTC).> |
| C2223 | Transmitter 3 Pressure Data Abnormal | Transmitter 3 data contents are abnormal. | <Ref. to DTC C2223 TRANSMITTER 3 PRESSURE DATA ABNORMAL , Diagnostic Procedure with Diagnostic Trouble Code (DTC).> |
| C2224 | Transmitter 4 Pressure Data Abnormal | Transmitter 4 data contents are abnormal. | <Ref. to DTC C2224 TRANSMITTER 4 PRESSURE DATA ABNORMAL , Diagnostic Procedure with Diagnostic Trouble Code (DTC).> |
| C2321 | Transmitter 1 Function Code Abnormal | Function code has error. | <Ref. to DTC C2321 TRANSMITTER 1 FUNCTION CODE ABNORMAL , Diagnostic Procedure with Diagnostic Trouble Code (DTC).> |
| C2322 | Transmitter 2 Function Code Abnormal | Function code has error. | <Ref. to DTC C2322 TRANSMITTER 2 FUNCTION CODE ABNORMAL , Diagnostic Procedure with Diagnostic Trouble Code (DTC).> |
| C2323 | Transmitter 3 Function Code Abnormal | Function code has error. | <Ref. to DTC C2323 TRANSMITTER 3 FUNCTION CODE ABNORMAL , Diagnostic Procedure with Diagnostic Trouble Code (DTC).> |
| C2324 | Transmitter 4 Function Code Abnormal | Function code has error. | <Ref. to DTC C2324 TRANSMITTER 4 FUNCTION CODE ABNORMAL , Diagnostic Procedure with Diagnostic Trouble Code (DTC).> |
| C2421 | Transmitter 1 Battery Voltage Low | Transmitter battery voltage is low. | <Ref. to DTC C2421 TRANSMITTER 1 BATTERY VOLTAGE LOW , Diagnostic Procedure with Diagnostic Trouble Code (DTC).> |
| C2422 | Transmitter 2 Battery Voltage Low | Transmitter battery voltage is low. | <Ref. to DTC C2422 TRANSMITTER 2 BATTERY VOLTAGE LOW , Diagnostic Procedure with Diagnostic Trouble Code (DTC).> |
| C2423 | Transmitter 3 Battery Voltage Low | Transmitter battery voltage is low. | <Ref. to DTC C2423 TRANSMITTER 3 BATTERY VOLTAGE LOW , Diagnostic Procedure with Diagnostic Trouble Code (DTC).> |
| C2424 | Transmitter 4 Battery Voltage Low | Transmitter battery voltage is low. | <Ref. to DTC C2424 TRANSMITTER 4 BATTERY VOLTAGE LOW , Diagnostic Procedure with Diagnostic Trouble Code (DTC).> |
| C2521 | Speed Abnormal | Vehicle speed signal is not input to the control module when the vehicle speed is 6 km/h (3.7 MPH) or more. | <Ref. to DTC C2521 SPEED ABNORMAL , Diagnostic Procedure with Diagnostic Trouble Code (DTC).> |
Factory Service Tools
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
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