P2128 2018 GMC Sierra Code - Accelerator Pedal Position Sensor 2 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
- P2128 2018 GMC Sierra indicates Accelerator Pedal Position Sensor 2 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 P2128 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 2 voltage is greater than 2.6 V for less than 1 s.
What are the Possible Causes of the DTC P2128 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 P2128 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 P2128 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 P2128 2018 GMC Sierra code?
Need more information on how to fix the P2128 2018 GMC Sierra code? Get Access to Factory Service Manuals
Need Help with the Code?
Get the P2128 2018 GMC Sierra code diagnosed by a professional: Find a repair shop in your area
Frequently Asked Questions about P2128 2018 GMC Sierra Code
1. What does the OBDII code P2128 mean on a 2018 GMC Sierra?
P2128 indicates a high voltage issue in the Accelerator Pedal Position Sensor 2 (APP Sensor 2) circuit, which monitors the position of the accelerator pedal.
2. What are the symptoms of code P2128 in a 2018 GMC Sierra?
Symptoms may include reduced engine power, difficulty accelerating, the throttle not responding properly, and the illumination of the check engine light.
3. What causes the P2128 code on a 2018 GMC Sierra?
Common causes include a faulty accelerator pedal position sensor, damaged wiring or connectors in the APP Sensor 2 circuit, or a malfunctioning engine control module (ECM).
4. Can I drive my 2018 GMC Sierra with the P2128 code?
While the vehicle may still be drivable, it will likely experience reduced performance. Prolonged driving without repairs could lead to further damage.
5. How do I fix the P2128 code on my 2018 GMC Sierra?
Repairs may involve replacing the APP sensor, repairing damaged wiring or connectors, or reprogramming or replacing the ECM if necessary.
6. How do I diagnose the P2128 code on a 2018 GMC Sierra?
Diagnosis involves using a scan tool to check for related codes, inspecting the APP sensor and its wiring for damage, and testing the voltage and continuity of the circuit.
7. How much does it cost to fix a P2128 code on a 2018 GMC Sierra?
Repair costs vary depending on the issue but typically range from $150 to $400 for parts and labor, with the accelerator pedal sensor being the most common replacement.
8. Can a dirty or stuck accelerator pedal cause the P2128 code?
While less common, a dirty or sticky pedal could impact sensor readings and should be inspected if other causes are ruled out.
9. Will clearing the P2128 code fix the problem on a 2018 GMC Sierra?
Clearing the code will temporarily turn off the check engine light but won’t resolve the underlying issue causing the high voltage in the APP Sensor 2 circuit.
10. Is the P2128 code related to the throttle body in a 2018 GMC Sierra?
Indirectly, yes. A faulty APP sensor or wiring can affect throttle body operation since the ECM uses APP sensor data to control throttle response.
Discuss the causes and fixes for P2128 2018 GMC Sierra OBDII Code
Code P2128 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.
