šØ Diagnostic Profile
Vehicle/Equipment Make: GENERIC
Technical Description: Throttle/Pedal Position Sensor/Switch A/B Voltage Correlation
This diagnostic code indicates a discrepancy between the two internal signal circuits (Sensor A and Sensor B) within the Throttle or Accelerator Pedal Position sensor assembly. Modern electronic throttle control (ETC) systems use dual, redundant sensors to ensure that the voltage readings match a predictable ratio at all times. When the Engine Control Module (ECM) detects a voltage correlation error between these two circuits that falls outside acceptable parameters, it triggers this fault to prevent unintended acceleration or throttle malfunction, often resulting in reduced power or ‘limp home’ mode.
šØ Repair Difficulty Tier
Rating: [Intermediate]
This repair requires an intermediate skill level. While the physical replacement of the sensor or pedal assembly is mechanically straightforward, accurately diagnosing the fault requires the use of a digital multimeter to check reference voltages, ground circuits, and signal wires. Additionally, a scan tool capable of reading live sensor data (PIDs) is necessary to compare the voltage correlation between Sensor A and Sensor B in real-time to confirm the sensor is faulty rather than the wiring harness.
š ļø Resolution Steps
Step 1: Preliminary Inspection
Begin by visually inspecting the wiring harness connector at the throttle body (if electronic throttle control) or at the base of the accelerator pedal assembly (if drive-by-wire pedal). Look for signs of corrosion, bent pins, chafed wires, or moisture intrusion. Check for any rodent damage along the harness routing. Ensure the electrical connector is fully seated and locked. Inspect the throttle body for physical obstructions or carbon buildup if this is a throttle-body-side code.
Step 2: Diagnostic Verification
Connect a scan tool and pull up live data for Throttle Position Sensor A and Sensor B (or Accelerator Pedal Position Sensor A and B). At idle, Sensor A typically reads approximately half the voltage of Sensor B (e.g., Sensor A: 0.5Vā1.0V, Sensor B: 1.5Vā2.0V), though exact values vary by manufacturer. Slowly depress the pedal or manually move the throttle plate (with key on, engine off) and observe that both voltage signals rise smoothly and proportionally without any skips, dropouts, or dead spots. Back-probe the connector with a multimeter to verify the 5V reference voltage and clean ground signal independently of the ECM if scan tool data appears erratic. A voltage that fails to correlate, jumps erratically, or drops to zero indicates an internal sensor fault or wiring issue.
Step 3: Resolution & Reset Process
If wiring and connectors test correctly but voltage correlation remains faulty, replace the throttle position sensor or the complete accelerator pedal assembly (as these sensors are often not sold separately from the pedal unit). After installation, clear the stored diagnostic trouble codes using the scan tool. Perform a throttle body relearn or idle relearn procedure if required by the manufacturer, as many ECMs need to recalibrate the minimum and maximum throttle position values after sensor replacement. Road test the vehicle while monitoring live data to confirm the code does not return and that acceleration response is smooth.
š¦ Parts, Labor, and Budget Estimates
Required Components/Software: Accelerator Pedal Position Sensor Assembly or Throttle Position Sensor, OEM-level scan tool with live data streaming capability, digital multimeter, dielectric grease for connector protection.
Average Component Price: $45 – $220 USD depending on vehicle make and whether the sensor is integrated into the pedal assembly or throttle body.
Estimated Labor Hours: 0.5 – 1.2 hours for diagnosis and replacement, plus an additional 0.2 – 0.4 hours if a throttle relearn or idle relearn procedure is required.