P2128 on Chevrolet: How to Diagnose & Fix
Throttle/Pedal Position Sensor E Circuit High Input
1 Chevrolet model · 1 documented issue · $100-$500 repair
P2128 on Chevrolet by model: symptoms, diagnosis and fix
The 2007-2013 Avalanche frequently enters "Reduced Engine Power" mode, severely limiting acceleration. The most common causes are the electronic throttle body wearing out or the accelerator pedal position sensor (APP sensor) developing faults. The vehicle becomes barely drivable in this mode, struggling to accelerate to highway speeds. The issue can occur intermittently before becoming permanent.
Common Symptoms
- "Engine Power Reduced" or "Reduced Engine Power" message on dash
- Vehicle struggles to accelerate past 20-30 mph
- Check engine light with P2128 or P2138 codes
- Intermittent power loss that resolves after restart
- Rough or hesitant throttle response
How to Fix
Diagnose with a scan tool to determine if the throttle body or accelerator pedal position sensor is the cause. Throttle body replacement costs $200-$400 parts and labor. APP sensor replacement costs $100-$250. A remanufactured throttle body from a quality source works well. Clear codes after repair and road test to verify.
What you need to diagnose it
The repair instructions explicitly call for reading stored codes. Use a scanner that can read the named code families before choosing a repair.The recommended scanner supports these code families; confirm your exact year, model and module coverage before buying.
ANCEL AD310 Classic OBD-II Scanner
Read & clear engine (P) codes
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Reading and clearing the code is DIY work. Module replacement or reprogramming is not — most modules are VIN-programmed, so a new one does nothing until a shop codes it to your car. Check for an open recall or service bulletin before buying anything.
Sources for this issue (1)
P2128 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P2128 mean on a Chevrolet?
P2128 stands for "Throttle/Pedal Position Sensor E Circuit High Input." This code means the throttle or accelerator pedal position sensor 'E' is sending a signal voltage higher than its normal expected range. Modern vehicles use electronic throttle control, where pedal and throttle sensors (often with redundant 'E/F' channels) tell the computer how far the driver is pressing and how far the throttle is open. A high-input reading indicates an electrical fault such as a short to voltage or a wiring problem in that sensor channel. The computer may limit throttle response or enter a reduced-power 'limp' mode for safety until the fault is resolved. On Chevrolet it is documented across 1 model: Avalanche.
What are the most common causes of P2128?
The most common causes of P2128 are: Faulty pedal/throttle position sensor (channel E), Wiring shorted to voltage or power, Corroded or damaged sensor connector, Open or high-resistance ground/reference circuit, Chafed or pinched harness wiring, Faulty accelerator pedal assembly or throttle body, Faulty engine control module (PCM) — rare. The specific cause varies by vehicle.
How much does it cost to fix P2128 on a Chevrolet?
Published repair estimates on Chevrolet range from $100 to $500 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
Looking for P2128 on a different make?
View P2128 across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.