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 Description
DTC DETECTION LOGIC
| DTC | CONSULT screen terms (Trouble diagnosis content) | DTC detection condition | |
| P2123-00 | APP SEN 1/CIRC (Throttle/Pedal position sensor/switch "D" circuit high) | Diagnosis condition | Engine running at idle |
| Signal (terminal) | Accelerator pedal position sensor 1 signal | ||
| Threshold | An excessively high voltage from the APP sensor 1 is sent to ECM | ||
| Diagnosis delay time | - | ||
POSSIBLE CAUSE
- Harness or connectors (APP sensor 1 circuit is open or shorted.)
- Accelerator pedal position sensor (APP sensor 1)
FAIL-SAFE
Engine Control System
| Fail safe mode | Vehicle behavior |
|---|---|
| Device fix mode |
|
Idle Start/Stop System
When a DTC is detected, the start/stop indicator lamp blinks slowly and the idle start/stop system operation is prohibited. When ECM detects error while operating the idle start/stop system, ECM restarts the engine.
NO RELATED
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
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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.