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 P2123
DTC P2123 : APP Sensor A (TP Sensor D) Circuit High Voltage
NOTE: Before you troubleshoot, review the general troubleshooting information .
| DTC Description | Confirmed DTC | Pending DTC | Freeze Frame |
|---|---|---|---|
| P2123 APP Sensor A (TP Sensor D) Circuit High Voltage |
DTC (PGM-FI)
- Problem verification
-1. Turn the vehicle to the ON mode.
-2. Check the parameter (s) below with the HDS.
Signal Threshold Current conditions Values Unit Values Unit APP SENSOR A More than 4.9 V Do the current condition (s) match the threshold?
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 APP sensor and the PCM. If the freeze data/on-board snapshot of this DTC is recorded, try to reproduce the failure under the same conditions with the freeze data/on-board snapshot .
- Determine possible failure area (APP sensor, others)
-1. Turn the vehicle to the OFF (LOCK) mode.
-2. Disconnect the following connector.
APP sensor 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 APP sensor 6P connector: disconnected Test point 1 APP sensor 6P connector No. 4 Test point 2 APP sensor 6P connector No. 5 Is there about 5.0 V?
YES
NO
Go to step 3.
- Open wire check (SG4 line)
-1. Turn the vehicle to the OFF (LOCK) mode.
-2. Jump the SCS line with the HDS.
-3. Disconnect the following connector.
PCM connector A (51P) -4. Connect terminals A and B with a jumper wire.
Terminal A APP sensor 6P connector No. 5 Terminal B Body ground -5. Check for continuity between test points 1 and 2.
Test condition Vehicle OFF (LOCK) mode APP sensor 6P connector: disconnected APP sensor 6P connector No. 5: jumped to body ground PCM connector A (51P): disconnected Test point 1 PCM connector A (51P) No. 48 Test point 2 Body ground Is there continuity?
YES
The SG4 wire is OK. Update the PCM if it does not have the latest software, or substitute a known-good PCM , then recheck. If DTC P2123 goes away and the PCM was updated, troubleshooting is complete. If DTC P2123 goes away and the PCM was substituted, replace the original PCM .
NO
Repair an open in the SG4 wire between the PCM (A48) and the APP sensor.
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.