🚨 Diagnostic Profile
Vehicle Make: BUICK
Technical Description: Accelerator Pedal Position Sensor 1 Circuit High Voltage
This diagnostic code indicates that the Powertrain Control Module (PCM) has detected a voltage signal from the Accelerator Pedal Position (APP) Sensor 1 that is higher than the expected calibrated range. This is typically caused by a wiring short to a voltage source, a faulty sensor, or a poor ground connection within the electronic throttle control system.
🚨 Repair Difficulty Tier
Difficulty Rating: Intermediate
This repair requires the use of a bi-directional scan tool capable of reading live APP sensor data (voltage counts) and a digital multimeter to test circuit integrity. While the physical replacement of the pedal assembly is straightforward, accurately diagnosing whether the fault lies in the wiring harness, the PCM, or the sensor itself requires intermediate automotive electrical knowledge. No airbag or restraint systems are involved, but this does affect vehicle acceleration safety, so proper verification is required before road testing.
🛠️ Resolution Steps
Step 1: Preliminary Inspection
Begin by visually inspecting the accelerator pedal assembly wiring harness for any signs of chafing, corrosion, or pinched wires, particularly near the firewall grommet and under-dash harness routing. Check the electrical connector at the pedal assembly for bent pins, corrosion, or moisture intrusion. Since this is a ‘High Voltage’ code (as opposed to ‘Low Voltage’), pay close specific attention to the signal wire to ensure it is not shorted against the 5-volt reference wire or a B+ power source.
Step 2: Diagnostic Verification
Connect a scan tool and navigate to the live data stream for the Accelerator Pedal Position Sensors (there are usually 3 sensors: P1, P2, and sometimes P3). With the key on and engine off, verify that Sensor 1 voltage reads within the standard operating range (typically between 0.5V and 4.5V) at idle/rest position. If the voltage is pegged at 5V or significantly higher than Sensor 2 and Sensor 3, this confirms an electrical circuit fault rather than a mechanical ones. Using a multimeter, backprobe the connector to check for a short to power on the signal circuit while wiggling the harness to check for intermittent faults.
Step 3: Resolution & Reset Process
If the wiring and connectors test positive (no shorts found) but the sensor voltage remains erratic or stuck high, replace the Accelerator Pedal Position Sensor assembly (this is usually an integrated unit, not a standalone sensor). After installation, clear the Diagnostic Trouble Codes (DTCs) using the scan tool. Perform a ‘Pedal Relearn’ or ‘Idle Relearn’ procedure if specified by the manufacturer for the PCM to recalibrate the new sensor’s baseline voltage. Conduct a test drive to ensure the Malfunction Indicator Lamp (MIL) does not return and that the vehicle accelerates smoothly without hesitation or limp-mode engagement.
📦 Parts, Labor, and Budget Estimates
Required Components/Software: Accelerator Pedal Position Sensor Assembly, Wiring Harness Repair Kit (if applicable), OBD-II Scan Tool with bi-directional controls.
Average Component Price: $80 – $250 USD (depending on if it is an aftermarket or OEM GM/ACDelco pedal assembly).
Estimated Labor Hours: 0.5 to 1.5 hours (Standard book time for diagnosis and pedal assembly replacement, excluding extensive wiring harness repairs which may add additional time).