Throttle/Pedal Position Sensor Circuit High Input
The P2123 code indicates that the Engine Control Module (ECM) has detected a voltage signal from the throttle/pedal position sensor that is higher than the expected range. This sensor is typically a dual-channel sensor (e.g., APP sensor) that provides redundant signals to ensure accurate throttle control. A high voltage reading can be caused by a short to power, a faulty sensor, or wiring issues. This condition can lead to reduced engine power, poor acceleration, or a failsafe mode where the throttle response is limited.
01. Most Common Causes
- Faulty throttle/pedal position sensor
- Short to voltage in sensor circuit wiring
- Damaged connector or corroded terminals
- ECM internal fault (rare)
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Reduced engine power or limp mode
- Poor throttle response or hesitation
- Erratic idle or stalling
03. Step-by-Step Diagnosis
Step 1: Connect a scan tool and verify the code P2123. Check for additional related codes (e.g., P2122, P2127).
Step 2: Inspect the throttle/pedal position sensor connector and wiring for damage, corrosion, or shorts to power.
Step 3: Using a multimeter, check the reference voltage (typically 5V) and ground at the sensor connector. Then measure the signal voltage while pressing the pedal; it should vary smoothly.
Step 4: If signal voltage is stuck high (e.g., >4.5V), disconnect the sensor and check if voltage drops. If it remains high, there is a short to power in the wiring. If it drops, replace the sensor.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive with this code as it can cause sudden loss of throttle control or unintended acceleration. The vehicle may enter limp mode, limiting speed and power. Have it diagnosed and repaired promptly.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150 for parts and labor. A new throttle position sensor costs around $20-$50, and labor is about $30-$100 depending on the vehicle and shop rates.