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 P0121 (L15B7/L15BA/L15BY) (17-21)
DTC P0121 : TP Sensor A Out of Range
NOTE: Before you troubleshoot, review the general troubleshooting information .
| DTC Description | Confirmed DTC | Pending DTC |
|---|---|---|
| P0121 TP Sensor A Out of Range |
- Problem verification
-1. Turn the vehicle to the ON mode.
-2. Clear the DTC with the HDS.
Clear DTC
-3. Wait 10 seconds or more.
-4. Check for Pending or Confirmed DTCs with the HDS.
DTC Description Confirmed DTC Pending DTC P0121 TP Sensor A Out of Range Is DTC P0121 indicated?
YES
The failure is duplicated. Go to step 2.
NO
Intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at the throttle body and the PCM. If the on-board snapshot of this DTC is recorded, try to reproduce the failure under the same conditions with the on-board snapshot .
- Determine possible failure area (THL1 line, others)
-1. Turn the vehicle to the OFF (LOCK) mode.
-2. Disconnect the following connector.
Throttle body 6P connector -3. Turn the vehicle to the ON mode.
-4. Measure the voltage between test points 1 and 2.
Test condition Vehicle ON mode Throttle body 6P connector: disconnected Test point 1 Throttle body 6P connector (female terminals) No. 3: Test point 2 Throttle body 6P connector (female terminals) No. 5: Is there about 5.0 V?
YES
Go to step 6.
NO
Go to step 3.
- Shorted wire check (VCC3 line)
-1. Turn the vehicle to the OFF (LOCK) mode.
-2. Jump the SCS line with the HDS, and wait more than 1 minute.
-3. Disconnect the following connector.
PCM connector E (80P) -4. Check for continuity between test points 1 and 2.
Test condition Vehicle OFF (LOCK) mode Throttle body 6P connector: disconnected PCM connector E (80P): disconnected Test point 1 Throttle body 6P connector (female terminals) No. 5: Test point 2 Body ground Is there continuity?
YES
Repair a short in the VCC3 wire between the PCM (E75) and the throttle body.
NO
The VCC3 wire is not shorted. Go to step 4.
- Open wire check (VCC3 line)
-1. Check for continuity between test points 1 and 2.
Test condition Vehicle OFF (LOCK) mode Throttle body 6P connector: disconnected PCM connector E (80P): disconnected Test point 1 Throttle body 6P connector (female terminals) No. 5: Test point 2 PCM connector E (80P) No. 75 Is there continuity?
YES
The VCC3 wire is OK. Go to step 5.
NO
Repair an open in the VCC3 wire between the PCM (E75) and the throttle body.
- Open wire check (SG3 line)
-1. Check for continuity between test points 1 and 2.
Test condition Vehicle OFF (LOCK) mode Throttle body 6P connector: disconnected PCM connector E (80P): disconnected Test point 1 Throttle body 6P connector (female terminals) No. 3: Test point 2 PCM connector E (80P) No. 76 Is there continuity?
YES
The SG3 wire is OK. Go to step 8.
NO
Repair an open in the SG3 wire between the PCM (E76) and the throttle body.
- Shorted wire check (THL1 line)
-1. Turn the vehicle to the OFF (LOCK) mode.
-2. Jump the SCS line with the HDS, and wait more than 1 minute.
-3. Disconnect the following connector.
PCM connector E (80P) -4. Check for continuity between test points 1 and 2.
Test condition Vehicle OFF (LOCK) mode Throttle body 6P connector: disconnected PCM connector E (80P): disconnected Test point 1 Throttle body 6P connector (female terminals) No. 6: Test point 2 Body ground Is there continuity?
YES
Repair a short in the THL1 wire between the PCM (E50) and the throttle body.
NO
The THL1 wire is not shorted. Go to step 7.
- Open wire check (THL1 line)
-1. Check for continuity between test points 1 and 2.
Test condition Vehicle OFF (LOCK) mode Throttle body 6P connector: disconnected PCM connector E (80P): disconnected Test point 1 Throttle body 6P connector (female terminals) No. 6: Test point 2 PCM connector E (80P) No. 50 Is there continuity?
YES
The THL1 wire is OK. Go to step 8.
NO
Repair an open in the THL1 wire between the PCM (E50) and the throttle body.
- Throttle body check
-1. Substitute a known-good throttle body .
-2. Reconnect all connectors.
-3. Exit the SCS mode with the HDS.
-4. Turn the vehicle to the ON mode.
-5. Clear the DTC with the HDS.
Clear DTC
-6. Wait 10 seconds or more.
-7. Check for Pending or Confirmed DTCs with the HDS.
DTC Description Confirmed DTC Pending DTC P0121 TP Sensor A Out of Range Is DTC P0121 indicated?
YES
The throttle body is OK. Check for any authorized service information related to the DTCs or symptoms you are troubleshooting, or substitute a known-good PCM , then recheck. If DTC P0121 goes away and the PCM was substituted, replace the original PCM .
NO
NO RELATED
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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.