P0641 on Chevrolet: How to Diagnose & Fix
Sensor Reference Voltage "A" Circuit/Open
1 Chevrolet model · 1 documented issue · 1 critical · $150-$700 repair
P0641 on Chevrolet by model: symptoms, diagnosis and fix
The GMT360 TrailBlazer uses a drive-by-wire throttle actuator control system with dual redundant sensors in both the throttle body and the accelerator pedal. When the two throttle position signals disagree the PCM sets P2135 and drops the truck into Reduced Engine Power limp mode — the vehicle will barely accelerate, which is dangerous when it happens pulling into traffic. Usual root causes are an internally failed electronic throttle body, a corroded or loose crimp in the throttle body connector, or moisture intrusion in the harness. Related codes P0641 (5V reference) and P1523 (throttle closed position performance) show up alongside it.
Common Symptoms
- 'Reduced Engine Power' message on the dash
- Vehicle will barely accelerate / limp mode
- Check engine light with P2135
- Rough or hunting idle
- Intermittent stall or no throttle response
How to Fix
Do not simply throw a throttle body at it. Inspect the throttle body connector terminals for a loose crimp between the terminal and the copper strands and for green corrosion — a widely reported fix on this platform. Clean carbon from the throttle bore, since heavy buildup causes P1523. If the two TPS signals still fail to track on a scan tool, replace the electronic throttle body assembly (roughly $150-400 for the part) and relearn idle. If pedal position codes appear instead, the accelerator pedal position sensor assembly is the culprit. No recall covers this.
Sources for this issue (3)
P0641 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 P0641 mean on a Chevrolet?
P0641 stands for "Sensor Reference Voltage "A" Circuit/Open." The control module detected an open or out-of-range condition on the 5-volt sensor reference 'A' supply circuit that powers multiple drivability sensors. The reference voltage is missing or incorrect. On Chevrolet it is documented across 1 model: TrailBlazer.
What are the most common causes of P0641?
The most common causes of P0641 are: Short or open in the 5V reference 'A' circuit, Shorted sensor pulling down the reference, Corroded/damaged connectors, Wiring chafe to power or ground, Internal PCM fault. The specific cause varies by vehicle.
How much does it cost to fix P0641 on a Chevrolet?
Published repair estimates on Chevrolet range from $150 to $700 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 P0641 on a different make?
View P0641 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.