🚨 Diagnostic Profile
Vehicle Make: BUICK
Technical Code Description: Accelerator Pedal Position Sensor 1 Circuit Low Voltage
This diagnostic trouble code indicates that the Engine Control Module (ECM) or Powertrain Control Module (PCM) has detected a voltage signal from the Accelerator Pedal Position (APP) Sensor 1 that is lower than the expected calibrated range. This sensor works alongside two other redundant sensors within the same pedal assembly to communicate the driver’s throttle input electronically. A low voltage reading typically points to a wiring fault, a failing sensor, or a poor ground connection within the pedal assembly circuit.
🚨 Repair Difficulty Tier
Difficulty Rating: Intermediate
This repair falls into the Intermediate category because it requires the use of a digital multimeter to test circuit continuity and voltage drop, along with a capable OBD-II scan tool to view live sensor data (PIDs) for all three APP sensor circuits simultaneously. While the pedal assembly itself is simple to mechanically remove, accurately diagnosing whether the fault lies in the wiring harness, the connector, or the sensor itself requires technical skill with electrical diagnostics. No complex module programming is typically required unless the ECM has been affected by a cascading electrical fault.
🛠️ Resolution Steps
Step 1: Preliminary Inspection
Begin with a visual inspection of the accelerator pedal assembly, typically located under the dash near the driver’s footwell. Check the wiring harness and electrical connector for signs of corrosion, pin damage, chafing, or a loose connection. Inspect for any aftermarket wiring, floor mats, or debris that may have pinched or damaged the harness near the pedal base. Confirm that the connector is fully seated and locked into place.
Step 2: Diagnostic Verification
Using an OBD-II scan tool, access live data streams for APP Sensor 1, 2, and 3. Compare the voltage outputs as you slowly depress the pedal; a healthy sensor should show a smooth, linear voltage increase from idle to wide-open throttle without dropouts. Back-probe the sensor connector with a digital multimeter to check for proper 5-volt reference voltage from the ECM and a stable ground signal. A reading significantly lower than 0.5V at idle (or outside manufacturer specification) with the key on confirms a low voltage fault, pointing to either a short to ground, a failing sensor, or a poor reference voltage supply.
Step 3: Resolution & Reset Process
If wiring and connectors test correctly but voltage remains low, replace the entire accelerator pedal assembly, as the APP sensors are typically non-serviceable and integrated into the pedal unit on most Buick models. After installation, clear the stored Diagnostic Trouble Codes (DTCs) using the scan tool. Perform a key-cycle relearn by turning the ignition to the “ON” position (engine off) for 30 seconds, then starting the vehicle to allow the ECM to recalibrate the new sensor baseline. Conduct a test drive while monitoring live data to confirm the code does not return and that throttle response is smooth.
📦 Parts, Labor, and Budget Estimates
Required Components/Software: Accelerator Pedal Assembly (with integrated sensor), OBD-II Scan Tool (capable of live data streaming), Digital Multimeter, Electrical Contact Cleaner (if corrosion is present).
Average Component Price: $75 – $220 USD for a new OEM or quality aftermarket pedal assembly, depending on the specific Buick model year and trim.
Estimated Labor Hours: 0.5 to 1.5 hours total, including diagnostic time, pedal assembly replacement, and post-repair verification/reset.