Diesel Trouble Codes

P2563 — Turbocharger Boost Control Position Sensor Circuit High (LLY / LBZ / LMM Duramax)

P2563 on LLY/LBZ/LMM Duramax means the ECM is seeing higher-than-expected voltage on the VGT turbocharger boost control position sensor circuit. The VGT uses…

Updated September 2, 2026

What it means

On LLY/LBZ/LMM Duramax 2004.5–2010 the turbo is variable-geometry with electric servo actuation and position feedback sensor. P2563 = Turbocharger Boost Control Position Sensor Circuit High per SAE J2012/GM enhanced. The ECM detects voltage on the position sensor circuit higher than expected.1

Most likely causes

  1. VGT position sensor signal circuit short to voltage / chafed wiring to harness power — High voltage on the position sensor signal wire can be caused by a short to a power feed or harness chafing in the engine bay. Inspect the VGT actuator/sensor harness and connectors for damage, oil/heat exposure, and pin corrosion. Compare to related VGT circuit codes P2564 (circuit low) and P003A (range/performance) which share the same sensor/actuator wiring.123
  2. Faulty VGT actuator / position sensor internal failure — The electric servo/position sensor assembly on the Garrett VGT can fail internally, pulling the signal high. This is common with heat cycling and oil contamination at the actuator. P003A range/performance and P2564 low circuit codes are associated with the same VGT position feedback hardware on LLY/LBZ/LMM.32
  3. ECM connector / reference voltage issue — Excess reference or pull-up voltage from the ECM driver can appear as a high sensor reading. Check ECM connectors for moisture/corrosion and verify reference voltage and ground integrity for the VGT position sensor circuit. VGT boost control solenoid circuit faults P0045 are in the same control family.4
  4. Contaminated / sticking VGT vanes causing abnormal actuator travel — Carbon buildup can cause the VGT mechanism to stick, forcing the actuator to its travel limit and the position sensor to report an out-of-range/high voltage condition. This can also set overboost P0234 or underboost P0299 on the VGT platform.5

How to diagnose

  1. Verify code and freeze frame; confirm P2563 is present on LLY/LBZ/LMM with VGT turbo.
  2. Inspect VGT actuator and wiring harness for heat/oil damage, chafing, and connector corrosion; check for shorts to voltage on sensor signal wire.
  3. Check ECM and actuator connector pin tension, moisture, and reference voltage/ground for the position sensor circuit.
  4. Command VGT actuator with scan tool and monitor desired vs actual position PID; look for stuck high reading or no movement.
  5. Inspect turbocharger intake/exhaust for excessive soot/carbon and check VGT vane freedom of movement via borescope if accessible; do not disassemble high-pressure fuel or brake systems.

Parts and tools you may need

Rough cost and difficulty

Parts and labor vary by sub-engine and shop. VGT actuator/sensor replacement and wiring repair costs differ from diagnostic labor only. No fixed price provided.

When to see a pro

If bi-directional control shows no actuator response, or wiring tests indicate an internal ECM driver fault, have a qualified diesel technician perform pinpoint electrical tests and ECM evaluation. Do not attempt high-pressure fuel or turbocharger disassembly without proper training and safety equipment.

Sources

  1. Curated DTC seed — LLY / LBZ / LMM Duramax (curated) ↩︎ ↩︎

  2. Curated DTC seed — LLY / LBZ / LMM Duramax (curated) ↩︎ ↩︎

  3. Curated DTC seed — LLY / LBZ / LMM Duramax (curated) ↩︎ ↩︎

  4. Curated DTC seed — LLY / LBZ / LMM Duramax (curated) ↩︎

  5. Curated DTC seed — LLY / LBZ / LMM Duramax (curated) ↩︎