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.
DTC C2121: TPM System Programming Malfunction: Testing
2000 Saturn LS1 AutomaticSECTION Testing
WARNING: This page is about a different car, the 2000 Chevrolet Corvette. However, it is still accessible from the selected car via links, so may be relevant.
- If tire pressure monitoring diagnostic system check has been performed, go to next step. If tire pressure monitoring diagnostic system check has not been performed, go to TIRE PRESSURE MONITORING (TPM) SYSTEM DIAGNOSTIC SYSTEM CHECK under DIAGNOSTIC TESTS in ANALOG INSTRUMENT PANELS - CORVETTE article.
- Using buttons on DIC, enter the TIRE TRAINING mode. See TIRE PRESSURE MONITOR (TPM) SENSOR PROGRAMMING under PROGRAMMING. If programming can be performed using DIC, go to next step. If programming cannot be performed using DIC, go to INSTRUMENT PANEL CLUSTER (IPC) DIAGNOSTIC SYSTEM CHECK under DIAGNOSTIC TESTS in ANALOG INSTRUMENT PANELS - CORVETTE article.
- Program all TPM sensors. If programming of TPM sensors is not successful, go to next step. If programming of TPM sensors is successful, go to step 5 .
- Check that all TPM sensors are installed and not damaged. See TIRE PRESSURE SENSOR under REMOVAL & INSTALLATION. If any TPM sensors are damaged or missing, go to step 7 . If all TPM sensors are present and not damaged, go to step 9 .
- Clear DTCs using scan tool. Road test vehicle above 15 mph for 20 minutes. If DTC C2121 resets, go to step 9 . If DTC C2121 does not reset, test is complete.
- Select display RFA DTCs function on scan tool. If DTC B2805 is set, go to step 8 . If DTC B2805 is not set, system is okay at this time.
- Replace TPM sensors as necessary. After repairs, go to step 10 .
- Program all TPM sensors. If programming of TPM sensors is successful, go to step 10 . If programming of TPM sensors is not successful, go to REMOTE KEYLESS ENTRY DIAGNOSTIC SYSTEM CHECK .
- Replace remote control door lock receiver. See REMOTE CONTROL DOOR LOCK RECEIVER under REMOVAL & INSTALLATION. After repairs, go to next step.
- Turn ignition off. Reconnect any disconnected components or connectors. Clear all DTCs. After repairs, go to TIRE PRESSURE MONITORING (TPM) SYSTEM DIAGNOSTIC SYSTEM CHECK under DIAGNOSTIC TESTS in ANALOG INSTRUMENT PANELS - CORVETTE article.
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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.