P2123 2018 GMC Sierra Code - Accelerator Pedal Position Sensor 1 Circuit High Voltage
Quick Answer
The Accelerator Pedal Assembly contains 2 Accelerator Pedal Position (APP) sensors. Common causes include Faulty Accelerator Pedal Position Sensor, Accelerator Pedal Position Sensor harness is open or shorted, Accelerator Pedal Position Sensor circuit poor electrical connection. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
- What it means
- P2123 2018 GMC Sierra indicates Accelerator Pedal Position Sensor 1 Circuit High Voltage.
- Common causes
- Common causes include Faulty Accelerator Pedal Position Sensor, Accelerator Pedal Position Sensor harness is open or shorted, Accelerator Pedal Position Sensor circuit poor electrical connection.
- Severity
- High - diagnose this code as soon as possible.
- Can I drive?
- Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
Code P2123 2018 GMC Sierra Description
Both the APP sensors 1 and 2 signal percentages increase as the pedal is depressed, from approximately 0 percent at rest to above 95 percent when fully depressed.
The Diagnostic Trouble Code (DTC) will be set when the ECM detects that the APP sensor 1 voltage is greater than 4.75 V for less than 1 s.
What are the Possible Causes of the DTC P2123 2018 GMC Sierra?
- Faulty Accelerator Pedal Position Sensor
- Accelerator Pedal Position Sensor harness is open or shorted
- Accelerator Pedal Position Sensor circuit poor electrical connection
- Faulty Engine Control Module (ECM)
How to Fix the DTC P2123 2018 GMC Sierra?
Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.
What is the Cost to Diagnose the Code?
Labor: 1.0
To diagnose the P2123 2018 GMC Sierra code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.
Need more information about the P2123 2018 GMC Sierra code?
Need more information on how to fix the P2123 2018 GMC Sierra code? Get Access to Factory Service Manuals
Need Help with the Code?
Get the P2123 2018 GMC Sierra code diagnosed by a professional: Find a repair shop in your area
Frequently Asked Questions about P2123 2018 GMC Sierra Code
What does OBDII code P2123 mean on a 2018 GMC Sierra?
P2123 indicates that the vehicle's Engine Control Module (ECM) has detected a high voltage signal from the Accelerator Pedal Position (APP) Sensor 1 circuit, suggesting a potential issue with the sensor or wiring.
What are the symptoms of code P2123 in a 2018 GMC Sierra?
Common symptoms include reduced engine performance, delayed throttle response, activation of "limp mode," and possible illumination of the check engine light.
What causes code P2123 in a 2018 GMC Sierra?
Causes may include a faulty APP sensor, damaged wiring or connectors in the APP circuit, short circuits, or issues with the ECM.
Can I drive my 2018 GMC Sierra with code P2123?
It is not recommended to drive the vehicle with this code active, as throttle control may be compromised, potentially leading to reduced drivability or unsafe conditions.
How is code P2123 diagnosed on a 2018 GMC Sierra?
A technician will inspect the APP sensor, wiring, and connectors for damage, perform voltage and resistance tests, and possibly use a scan tool to monitor sensor data and ECM functionality.
How do you fix code P2123 on a 2018 GMC Sierra?
Repairs may include replacing the APP sensor, repairing or replacing damaged wiring or connectors, or reprogramming or replacing the ECM if needed.
Can a dirty accelerator pedal cause code P2123?
No, a dirty accelerator pedal typically does not cause this code, as it is related to electrical signals rather than mechanical issues.
How much does it cost to repair code P2123 on a 2018 GMC Sierra?
Repair costs can vary, but replacing the APP sensor typically costs $100-$300, while wiring repairs or ECM replacements may increase costs significantly.
Does code P2123 require ECM reprogramming?
In some cases, ECM reprogramming or replacement may be necessary if the issue originates from the ECM itself or if sensor calibration is required.
Can a faulty APP sensor damage the engine on a 2018 GMC Sierra?
A faulty APP sensor is unlikely to cause direct engine damage but can lead to drivability issues that might strain other components if left unaddressed.
Discuss the causes and fixes for P2123 2018 GMC Sierra OBDII Code
Code P2123 2018 GMC Sierra comments
No comments found for this page.
Fix Your Car Smarter
Try the New AutoCodes App!
Get complete OBDII diagnostics, repair solutions, and cost estimates, plus AI chat support on demand.
