🚨 Diagnostic Profile
Vehicle Make: BUICK
Technical Description: Accelerator Pedal Position (APP) Sensor 1 Performance
This diagnostic trouble code indicates that the Powertrain Control Module (PCM) has detected an irrational or out-of-range signal from the primary Accelerator Pedal Position sensor. Since most modern Buick models utilize an electronic ‘drive-by-wire’ throttle system, this sensor is critical for communicating driver throttle input to the engine computer. A fault here often triggers ‘Reduced Engine Power’ mode to prevent unintended acceleration.
🚨 Repair Difficulty Tier
Rating: [Intermediate]
This repair requires the use of a professional-grade scan tool capable of reading live bi-directional data (Mode $06 or enhanced PIDs) to compare sensor voltage readings for Sensor 1 vs. Sensor 2. While the physical replacement of the pedal assembly is straightforward (hand tools only), accurately diagnosing whether the fault lies in the wiring harness, the pedal sensor, or the PCM itself requires an intermediate understanding of multiplexed voltage signals and multimeter usage.
🛠️ Resolution Steps
Step 1: Preliminary Inspection
Begin by visually inspecting the wiring harness connector located at the base of the accelerator pedal assembly under the dash. Look for corrosion, bent pins, or chafed wires caused by rubbing against the driver’s side kick panel. Check for any aftermarket floor mats that may be interfering with the pedal’s full range of motion, as this can sometimes trigger performance codes by restricting travel.
Step 2: Diagnostic Verification
Connect an OBD-II scan tool and navigate to live data streams. Monitor the Accelerator Pedal Position sensors 1, 2, and 3 simultaneously. As you slowly depress the pedal by hand (key on, engine off), the voltage percentages should rise in a smooth, linear, and simultaneous fashion. If Sensor 1 lags, jumps erratically, or fails to reach 100% while others do, this confirms an internal sensor fault. Additionally, back-probe the connector with a multimeter to verify a steady 5-volt reference signal from the PCM and a solid ground.
Step 3: Resolution & Reset Process
If the live data confirms an internal sensor discrepancy, replace the entire accelerator pedal assembly, as the sensor is typically non-serviceable and integrated into the pedal unit. After installation, clear the Diagnostic Trouble Codes (DTCs) using the scan tool. It is recommended to perform a Throttle Relearn/Reset procedure (if applicable to the specific Buick model) to allow the PCM to recalibrate the idle and pedal parameters. Perform a test drive to ensure the ‘Reduced Power’ mode does not re-engage.
📦 Parts, Labor, and Budget Estimates
Required Components/Software: OEM Accelerator Pedal Assembly (incorporating APP Sensor), Electrical Contact Cleaner (if corrosion is found), OBD-II Scan Tool with live data capability.
Average Component Price: $120 – $250 for the OEM pedal assembly.
Estimated Labor Hours: 0.5 – 1.0 hour for diagnosis and replacement, as the component is typically mounted with 2-3 bolts and a single electrical connector.