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: TP Sensor A Out of Range (L4) (2018-19)
NOTE: Before you troubleshoot, review the general troubleshooting information - Refer to: How to Troubleshoot the Fuel and Emissions Systems (L4) .
| DTC Description | Confirmed DTC | Pending DTC |
|---|---|---|
| P0121 TP Sensor A Out of Range |
DTC (PGM-FI)
- Problem verification 1
-1. Turn the vehicle to the ON mode.
- 2. Clear the DTC with the HDS.
- 3. Turn the vehicle to the OFF (LOCK) mode.
- 4. Turn the vehicle to the ON mode.
- 5. Check the parameter (s) below with the HDS.
Signal Threshold Current conditions Values Unit Values Unit TP SENSOR A Less than 0.42 V Do the current condition (s) match the threshold?
YES
The failure is duplicated. Go to step 3.
NO
Go to step 2.
- Problem verification 2
-1. Check the parameter (s) below with the HDS.
Signal Threshold Current conditions Values Unit Values Unit TP Sensor More than 4.63 V Do the current condition (s) match the threshold?
YES
The failure is duplicated. Go to step 7.
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 - Refer to: How to Troubleshoot the Fuel and Emissions Systems (L4) .
- Determine possible failure area (THL1 line, others)
-1. Check for Pending or Confirmed DTCs with the HDS.
DTC Description Confirmed DTC Pending DTC P0121 TP Sensor A Out of Range P0221 TP Sensor B Out of Range Are DTC P0121 and P0221 indicated at the same time?
YES
Go to step 5.
NO
Go to step 4.
- 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 connectors.
PCM connector C (51P) Throttle body 6P connector - 4. Check for continuity between test points 1 and 2.
Test condition Vehicle OFF (LOCK) mode PCM connector C (51P): disconnected Throttle body 6P connector: 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 (C28) and the throttle body.
NO
The THL1 wire is OK. Check for any authorized service information related to the DTCs or symptoms you are troubleshooting, or substitute a known-good PCM - Refer to: PCM Removal and Installation (Without SH-AWD) .
- Determine possible failure area (throttle body, 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. 5: Test point 2 Body ground Is there about 5.0 V?
YES
Replace the throttle body - Refer to: Throttle Body Removal and Installation (L4) .
NO
Go to step 6.
- Open wire check (VCC3 (DBW) 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 C (51P) - 4. Check for continuity between test points 1 and 2.
Test condition Vehicle OFF (LOCK) mode Throttle body 6P connector: disconnected PCM connector C (51P): disconnected Test point 1 Throttle body 6P connector (female terminals) No. 5: Test point 2 PCM connector C (51P) No. 40 - Refer to: PCM Connector for Inputs and Outputs (L4) (2018-19) . Is there continuity?
YES
The VCC3 (DBW) wire is OK. Check for any authorized service information related to the DTCs or symptoms you are troubleshooting, or substitute a known-good PCM - Refer to: PCM Removal and Installation (Without SH-AWD) .
NO
Repair an open in the VCC3 (DBW) wire between the PCM (C40) and the throttle body.
- Determine possible failure area (SG3 (DBW) line, others)
-1. Check for Pending or Confirmed DTCs with the HDS.
DTC Description Confirmed DTC Pending DTC P0121 TP Sensor A Out of Range P0221 TP Sensor B Out of Range Are DTC P0121 and P0221 indicated at the same time?
YES
Go to step 10.
NO
Go to step 8.
- Determine possible failure area (throttle body, 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. 6: Test point 2 Body ground Is there about 5.0 V?
YES
Replace the throttle body - Refer to: Throttle Body Removal and Installation (L4) .
NO
Go to step 9.
- Open 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 C (51P) - 4. Check for continuity between test points 1 and 2.
Test condition Vehicle OFF (LOCK) mode Throttle body 6P connector: disconnected PCM connector C (51P): disconnected Test point 1 Throttle body 6P connector (female terminals) No. 6: Test point 2 PCM connector C (51P) No. 28 - Refer to: PCM Connector for Inputs and Outputs (L4) (2018-19) . Is there continuity?
YES
The THL1 wire is OK. Check for any authorized service information related to the DTCs or symptoms you are troubleshooting, or substitute a known-good PCM - Refer to: PCM Removal and Installation (Without SH-AWD) .
NO
Repair an open in the THL1 wire between the PCM (C28) and the throttle body.
- Open wire check (SG3 (DBW) 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 connectors.
PCM connector C (51P) Throttle body 6P connector - 4. Check for continuity between test points 1 and 2.
Test condition Vehicle OFF (LOCK) mode PCM connector C (51P): disconnected Throttle body 6P connector: disconnected Test point 1 Throttle body 6P connector (female terminals) No. 3: Test point 2 PCM connector C (51P) No. 39 - Refer to: PCM Connector for Inputs and Outputs (L4) (2018-19) . Is there continuity?
YES
The SG3 (DBW) wire is OK. Check for any authorized service information related to the DTCs or symptoms you are troubleshooting, or substitute a known-good PCM - Refer to: PCM Removal and Installation (Without SH-AWD) .
NO
Repair an open in the SG3 (DBW) wire between the PCM (C39) and the throttle body.
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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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