P0045 — Turbocharger Boost Control Solenoid A Circuit/Open — LLY / LBZ / LMM Duramax
P0045 on LLY/LBZ/LMM Duramax indicates an electrical fault in the VGT control solenoid circuit. The Garrett GT3788VA uses engine oil pressure metered by an…
What it means
Generic definition: ECM detected an open or electrical fault in the turbocharger boost control (VGT) solenoid A circuit. On LLY/LBZ/LMM the Garrett GT3788VA vanes are moved hydraulically by engine oil pressure metered by the ECM-controlled VGT control solenoid, with vane position reported by a vane position sensor. P0045 is the VGT control solenoid circuit fault.1
Most likely causes
- Open or failed VGT control solenoid coil — Solenoid coil open or internally failed; ECM cannot drive the solenoid. Typical on this platform: check solenoid coil, connector and wiring, and ECM driver; a solenoid that is open or unplugged leaves vanes uncontrolled.1
- Disconnected or corroded VGT solenoid connector at turbo — Connector unplugged, backed out pins, oil contamination or corrosion at the turbo-mounted solenoid connector opens the circuit.1
- Chafed/broken wiring or poor ground in VGT solenoid harness — Harness chafing near turbo/heat shields, broken wires, or high resistance ground causes an open/electrical fault in the solenoid circuit.1
- ECM driver fault for VGT solenoid — Internal ECM driver failure or related power/ground issue prevents solenoid actuation; verify circuit integrity before condemning ECM.1
How to diagnose
- Verify code and freeze frame; confirm P0045 is present and note engine conditions at set.
- Visually inspect VGT control solenoid connector at turbo for secure engagement, oil intrusion, bent/corroded terminals; repair connector as needed.
- Inspect VGT solenoid wiring harness from solenoid to ECM for chafing, heat damage, oil saturation, and continuity; pay attention to turbo/heat shield routing.
- Measure VGT control solenoid coil resistance at the solenoid connector per service spec; compare to known-good values; replace solenoid if open/shorted. Note: solenoid is oil-metering, not electrically actuated vanes.
- With key on/engine off, check solenoid supply and control circuits for battery voltage and ECM command presence; verify reference/ground integrity.
- If circuit tests normal, perform ECM pin-out checks for driver output and wiring continuity to rule out harness/ECM faults before replacing ECM.
- Clear codes and command VGT solenoid with scan tool while monitoring vane position sensor feedback; confirm electrical control is restored and no related P003A/P2563/P2564 set.
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
- Service information wiring diagram
Tools you’ll need
- digital multimeter — Measures VGT solenoid coil resistance and checks supply/command voltage and ground integrity in the solenoid circuit.
- OBD-II scan tool — Reads P0045 freeze frame and commands the VGT solenoid while monitoring vane position sensor feedback for control restoration.
- inspection mirror — Allows visual inspection of the VGT solenoid connector and harness routing at the hot turbo without full disassembly.
- wire piercing probes — Enables safe voltage and continuity checks of the VGT solenoid wiring from the turbo to the ECM without cutting insulation.
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 |
| Engine wiring harness section | $100–$500 | 2–5 hrs | Shop |
| 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 wiring tests normal but ECM cannot drive the solenoid, or if intermittent faults persist after connector/harness repair, have the ECM and circuits evaluated by a qualified diesel technician. Do not attempt high-pressure fuel system service without proper training and safety equipment.
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
Repair videos: P0045 on the LLY-LMM Duramax
Third-party videos, not ours — picked for this engine. Confirm anything against the factory service information for your truck.
Spotted an error, or something missing? Tell us
Run a LLY / LBZ / LMM Duramax? This goes straight to the editor — it is not published.