🚨 Diagnostic Profile
- Vehicle/Equipment Make: CADILLAC
- Technical Description: Accelerator Pedal Position Sensor 1
P1273 is a Powertrain code monitored by the Engine Control Module (ECM) or Powertrain Control Module (PCM). This code indicates that the PCM has detected an irregularity in the signal from Accelerator Pedal Position (APP) Sensor 1, which is one of typically two or three redundant sensors mounted within the accelerator pedal assembly. The PCM continuously cross-checks the voltage outputs of all APP sensors against each other to ensure they correlate properly as the driver presses the pedal. If Sensor 1’s signal falls outside the expected range, is erratic, or disagrees with the other sensors beyond a calibrated threshold, the PCM sets P1273. Because the accelerator pedal on this platform operates on a drive-by-wire system (Electronic Throttle Control), an inaccurate or implausible signal from this sensor can cause the PCM to activate reduced power modes, illuminate the Check Engine Light, and in some cases trigger limp-mode throttle response as a safety precaution to prevent unintended acceleration.
🚨 Repair Difficulty Tier
- Difficulty Rating: Intermediate
This repair requires a scan tool capable of reading live APP sensor voltage data and bi-directional diagnostics, along with a digital multimeter to verify wiring integrity and sensor output voltages. While replacing the pedal assembly itself is straightforward, accurately diagnosing whether the fault lies in the sensor, wiring harness, or PCM requires some electrical diagnostic experience.
🛠️ Resolution Steps
- Step 1: Preliminary Inspection
Begin by visually inspecting the accelerator pedal assembly, its electrical connector, and the wiring harness that runs to the PCM. Look for corrosion, loose pins, chafed wires, or moisture intrusion at the connector, as these are common causes of intermittent APP sensor faults. - Step 2: Diagnostic Verification
Connect a scan tool and monitor live data for APP Sensor 1, 2, and 3 (if equipped) while slowly depressing and releasing the pedal. The sensors should move smoothly and proportionally together without dropouts or erratic jumps. Use a digital multimeter at the connector to confirm the reference voltage (typically 5V), ground, and signal output are within factory specification across the full pedal travel range. - Step 3: Resolution & Reset Process
If the sensor signal is erratic or out of range and wiring tests clean, replace the accelerator pedal sensor assembly (most pedal sensors are integrated into the pedal unit and are not separately serviceable). After installation, clear the stored code with the scan tool, perform a throttle relearn procedure if required by the vehicle, and test drive while monitoring live data to confirm the fault does not return.
📦 Parts, Labor, and Budget Estimates
- Required Components/Software: Accelerator pedal position sensor assembly, OEM-level or advanced scan tool with bi-directional control, digital multimeter, wiring harness repair kit (if needed)
- Average Component Price: $85 – $220 USD
- Estimated Labor Hours: 0.5 – 1.0 hour
- Total Estimated Budget: $150 – $320 USD