Diesel Trouble Codes

P2563 — Turbocharger Boost Control Position Sensor A Circuit Range/Performance — LLY / LBZ / LMM Duramax

P2563 on LLY/LBZ/LMM Duramax indicates the VGT vane position sensor signal is outside its expected range or does not track the commanded position. The Garrett…

Updated October 15, 2026

What it means

Generic definition: The VGT position sensor signal is outside its expected range or does not track the commanded position. On LLY/LBZ/LMM the Garrett GT3788VA vanes are moved hydraulically by engine oil pressure metered by the ECM-controlled VGT control solenoid, and a vane position sensor reports position. Range/performance faults point to the vane position sensor, its connector and wiring, or sticking vanes/low oil supply that make the reported position disagree with the command.1

Most likely causes

  1. Vane position sensor internal failure or drift — Sensor output voltage is out of range or does not follow actual vane travel, triggering range/performance. Typical on this platform for P2563/P2564.12
  2. Connector or wiring fault at the turbo vane position sensor — Corrosion, oil contamination, or chafed harness at the turbo changes signal/reference voltage and causes range/performance disagreement.12
  3. Sticking/sooted VGT vanes or unison ring — Carbon buildup restricts vane movement so actual position lags or differs from commanded position, causing a range/performance mismatch. Often accompanied by learning-limit or overboost/underboost codes.13
  4. Low or aerated engine oil supply to the VGT actuator — Insufficient oil pressure/volume to the hydraulic actuator makes vane movement slow or erratic, so reported position does not track command.13
  5. VGT control solenoid performance issue affecting vane motion — Solenoid sticking or oil contamination alters oil metering to the actuator, leading to position tracking errors even if the sensor is good.134

How to diagnose

  1. Verify freeze frame and related codes: check for P2564, P003A, P0045, P0234, P0299. Multiple VGT codes point to mechanical/hydraulic issues rather than sensor alone.
  2. Inspect the turbo vane position sensor connector and wiring at the turbo for oil intrusion, corrosion, bent pins, and chafing along the harness to the ECM.
  3. Check sensor reference and signal voltages at the connector with key on/engine off and compare to expected values; look for opens/shorts to ground or power.
  4. Command VGT vane position with a scan tool and monitor actual vs desired position. A lagging or non-tracking actual position suggests mechanical/hydraulic restriction or sensor fault.
  5. Inspect engine oil condition and level; check for aeration or restriction to the VGT actuator oil feed. Low or aerated oil supply can cause slow/erratic vane response.
  6. Perform a visual inspection of the turbocharger for excessive soot buildup, sticking vanes, or unison ring binding; do not disassemble the turbo’s vane actuator.
  7. If the sensor and wiring test good but position tracking remains poor, suspect sticking vanes/unison ring or VGT solenoid performance and address those before replacing the sensor.
  8. After repairs, clear codes and perform a VGT relearn if supported; confirm actual position tracks commanded across idle to load.

Common mistake to avoid

Replacing the turbo before smoke-testing the intake. Boost leaks at intercooler boots, end tanks and clamps are a common cause of low power and underboost codes, and they mimic a failing turbo. Source: BD Diesel — 6.7L Power Stroke problems and real fixes.

Parts and tools you may need

Tools you’ll need

Rough cost and difficulty

Likely repairPartsShop laborWho usually does it
Wiring or connector repair$10–$1001–4 hrsDIY with tools and a manual
VGT actuator / vane control solenoid$100–$4000.5–2 hrsDIY with tools and a manual
Turbocharger$1,500–$3,5004–10 hrsShop

Typical US independent-shop figures; labor runs about $120–$180 per hour (dealers charge more). Confirm the diagnosis before buying parts.

When to see a pro

If bi-directional control shows no change in actual position, or if the turbo requires removal for vane cleaning/rebuild, have a qualified diesel technician service the VGT assembly. Turbo and VGT actuator work require experience and proper safety precautions.

Check for recalls

Recalls are tied to your truck’s VIN, so check yours directly: enter the VIN at NHTSA’s recall lookup. Open safety recalls are repaired free at a dealer.

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) ↩︎