Diesel Trouble Codes

P2563 — Turbocharger Boost Control Position Sensor Circuit High (L5P Duramax)

P2563 on L5P Duramax indicates the ECM sees the VGT position sensor voltage higher than expected. The L5P uses a variable-geometry turbo with an electric…

Updated September 2, 2026

What it means

The ECM monitors the VGT actuator position sensor circuit. A ‘circuit high’ reading means the signal voltage is above the calibrated range, so the ECM cannot trust the actual vane position feedback. This is a sensor-circuit/electrical fault, not a confirmed mechanical overboost condition. The L5P turbo is VGT with electric actuator and position sensor, no wastegate.12

Most likely causes

  1. VGT actuator position sensor internal failure or biased high output — Sensor element drift or short to voltage pulls the signal high. Typical for P2563 on L5P VGT system.12
  2. Wiring/connector fault to the VGT actuator position sensor — Chafed, corroded, or oil-contaminated connector at the turbo actuator causes high resistance/open to ground or short to voltage on the signal wire.12
  3. VGT electric actuator failure affecting position feedback — Actuator motor or internal position feedback potentiometer fault can drive the reported position voltage high. L5P uses electric VGT actuator with position sensor.12
  4. ECM reference voltage or ground issue for the position sensor circuit — Excessive 5 V reference or poor sensor ground raises the measured signal. Diagnose circuit integrity before condemning the turbo.1
  5. Contaminated or damaged turbo actuator connector from oil/heat — Heat and oil exposure at the turbo can degrade the actuator harness, leading to intermittent high-voltage readings.12

How to diagnose

  1. Verify code and freeze frame; confirm P2563 is present and check for companion codes P003A, P2564, P0234, P0299.
  2. Inspect VGT actuator and wiring harness for heat damage, oil contamination, chafing, and connector pin corrosion at the turbo.
  3. Check ECM data for VGT position sensor voltage at key-on/engine-off and at idle; compare to spec and look for stuck high reading.
  4. Perform circuit tests on sensor signal, 5 V reference, and ground per wiring diagram; isolate wiring fault vs actuator/sensor.
  5. If circuits test normal, evaluate VGT actuator/position sensor operation with a scan tool bi-directional command and monitor actual vs desired position.
  6. Inspect intake/boost system for leaks or restrictions only if accompanied by P0299 underboost; boost leak causes underboost, not overboost, on L5P.

Parts and tools you may need

Rough cost and difficulty

Parts and labor vary by region and shop. Turbo actuator replacement is more expensive than sensor/wiring repair. Always confirm circuit integrity before replacing the turbo assembly.

When to see a pro

If bi-directional tests show no response, or the actuator is seized/damaged internally, have a qualified diesel technician evaluate the VGT assembly. Do not attempt high-pressure fuel or turbo disassembly without proper training and safety controls.

Sources

  1. Curated DTC seed — L5P Duramax (curated) ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎

  2. Curated DTC seed — L5P Duramax (curated) ↩︎ ↩︎ ↩︎ ↩︎ ↩︎