P2564 — Turbocharger Boost Control Position Sensor A Circuit Low — L5P Duramax
Diagnostic reference for L5P Duramax (2017–present) P2564.
What it means
Generic definition: the VGT position sensor signal voltage is below its valid range. On L5P Duramax this is a turbocharger VGT position sensor circuit low condition for the electric VGT actuator position sensor.1
Most likely causes
- VGT actuator position sensor connector or wiring fault causing low signal voltage — Inspect the VGT actuator position sensor connector for corrosion, loose terminals, or damaged wiring that can pull the signal low. Check harness routing near hot turbo components for chafing or heat damage.1
- VGT actuator internal position sensor failure — The electric VGT actuator contains the position sensor; an internal sensor fault can produce a persistently low voltage signal.1
- PCM reference or ground circuit issue affecting the sensor supply — A low reference voltage or poor ground to the VGT position sensor circuit can cause the signal to read below valid range.1
How to diagnose
- Verify code P2564 is present and review freeze-frame data for engine speed, load, and temperature at set.
- Inspect the VGT actuator position sensor connector and wiring for corrosion, loose pins, or heat/chafe damage; repair wiring faults as needed.
- Check the VGT actuator position sensor signal voltage with a scan tool during key-on and engine running; compare to expected range and look for a stuck low reading.
- If wiring and connector are intact, evaluate the VGT actuator assembly; a faulty internal position sensor typically requires actuator replacement and a VGT relearn after repair.
- After repairs, clear codes and command VGT position sweep with a scan tool to confirm sensor tracks command and no P2564/P2563 returns.
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
- Digital multimeter
- Scan tool with bi-directional VGT control
- Terminal release tools
- Dielectric grease
Tools you’ll need
- bi-directional scan tool — Commands VGT position sweep and reads live VGT position sensor voltage to confirm a stuck low signal for P2564.
- digital multimeter — Measures sensor supply, ground, and signal voltage at the VGT actuator connector to find a low signal or wiring fault.
- inspection mirror — Views the VGT actuator connector and wiring harness in the tight turbo area for corrosion, loose pins, or heat/chafe damage.
- terminal release tool set — Safely releases and reseats VGT actuator connector terminals to correct poor contact causing low signal voltage.
Rough cost and difficulty
| Likely repair | Parts | Shop labor | Who usually does it |
|---|---|---|---|
| Wiring or connector repair | $10–$100 | 1–4 hrs | DIY with tools and a manual |
| VGT actuator / vane control solenoid | $100–$400 | 0.5–2 hrs | DIY with tools and a manual |
| ECM/PCM replacement (programmed) | $600–$2,000 | 1–3 hrs | Shop |
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 the VGT actuator or high-pressure fuel system is suspected, have a qualified diesel technician perform diagnosis. Do not attempt repairs on high-pressure fuel injection systems. Seek professional help for any safety-critical system work.
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
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