P0045 Turbocharger Boost Control Solenoid Circuit Open: Diagnosis & Fix

The P0045 Turbocharger Boost Control Solenoid Circuit Open code is one of the most common boost-related faults we see come through the shop, and it trips up plenty of experienced techs because the name points you in the wrong direction. This is not a mechanical turbo failure code. It is an electrical circuit fault telling you the ECM has detected an open condition in the wiring, connector, or solenoid that controls boost pressure. Chase the turbo first and you will waste a day and a lot of money.

At PT Turbo we have been diagnosing and rebuilding turbochargers since 1978, over 45 years of hands-on experience, and we stock both new and remanufactured actuators, solenoids, and complete turbo assemblies. This guide walks you through exactly what P0045 means, how to test the circuit properly, and how to fix it right the first time.

What the P0045 Code Actually Means

P0045 is a generic OBD-II powertrain code that sets when the engine control module reads an open circuit in the turbocharger or supercharger boost control solenoid control circuit. On diesel applications this solenoid, sometimes called a boost control valve or wastegate/vane control solenoid, regulates the vacuum or pressure signal that positions the turbo actuator.

The ECM commands the solenoid with a duty-cycle signal. When it sends that command and reads no current flow, or resistance outside spec, it logs P0045. “Open” specifically means the circuit is broken: think corroded pins, a chafed wire, a failed solenoid coil, or a disconnected plug.

On variable-geometry turbos (VGT), this solenoid ultimately drives vane position, which is why the fix sometimes overlaps with actuator problems. If you want a deeper dive on how VGT hardware works, the variable-geometry turbocharger breakdown is a solid reference.

Symptoms of a P0045 Fault

Because the solenoid can no longer modulate boost, the turbo typically defaults to a fail-safe position. On most diesels that means low boost and a noticeable drop in power. Symptoms range from mild to limp-mode depending on the platform.

Severity	Symptoms	Drivability Impact
Mild	Check engine light, slightly sluggish throttle response	Truck still drives, minor power loss
Moderate	Noticeable underboost, hesitation under load, poor fuel economy	Struggles on grades and while towing
Severe	Limp mode, RPM cap, black smoke, derate	Reduced speed, unsafe for heavy loads

P0045 rarely travels alone. It often shows up alongside underboost or overboost codes when the solenoid or actuator cannot hold position. If you are also seeing boost pressure faults, cross-reference our guides on the P0299 underboost code and the P0234 overboost code to rule out mechanical boost leaks.

Common Causes of P0045 Turbocharger Boost Control Solenoid Circuit Open

The word “open” narrows the field considerably. You are looking for a break in continuity somewhere in the control circuit. In our experience, the causes stack up in this rough order of frequency:

• Corroded or damaged connector at the solenoid or actuator. Heat cycling and road salt destroy these pins.
• Chafed or broken wiring in the harness, especially where it routes near hot exhaust components or sharp brackets.
• Failed solenoid coil, an internal open in the winding that reads infinite resistance.
• Failed electronic actuator on VGT turbos where the motor and control circuit are integrated.
• Poor ground or blown fuse feeding the boost control circuit.
• ECM driver failure, rare, but it happens after repeated shorts.

Before you condemn any part, remember that vacuum leaks, cracked boost lines, and sticking wastegate linkages can mimic the drivability symptoms. But a true P0045 is electrical, so your multimeter, not your boost gauge, is the primary tool here.

How to Diagnose P0045 Step by Step

Work the circuit methodically. Skipping steps is how techs end up replacing a good turbo. Here is the procedure we follow on the bench and in the bay.

Step 1: Scan and Record Freeze Frame Data

Pull all codes with a capable scan tool, not just a cheap reader. Note freeze-frame data: RPM, load, and commanded versus actual boost when P0045 set. This tells you whether the fault is constant or intermittent.

Step 2: Inspect the Connector and Wiring

Disconnect the boost control solenoid or actuator plug. Look for green corrosion, spread pins, melted plastic, and oil intrusion. Wiggle-test the harness while watching live data or with the DMM connected. A high percentage of P0045 faults are found right here.

Step 3: Test Solenoid Resistance

With the connector off, measure resistance across the solenoid terminals. Most boost control solenoids spec between roughly 15 and 30 ohms, though you should verify against OEM values for your engine. An infinite (OL) reading confirms an internal open, which means the solenoid is bad.

Step 4: Check Circuit Continuity to the ECM

Back-probe the control wire and confirm continuity from the connector to the ECM pin. An open here is a broken wire or bad connector body. Also verify the power feed and ground on the circuit.

Step 5: Verify the Command Signal

With everything reconnected, use your scan tool to command the solenoid or actuator through its sweep. Watch for smooth actuation. On electronic VGT actuators, a self-calibration routine that fails or stalls points to the actuator itself.

Fixing P0045: Parts and Repair Options

Once you have isolated the fault, the repair is straightforward. Wiring and connector issues get repaired with proper solder, heat shrink, and OEM-grade terminals. Do not rely on crimp-only butt connectors in a high-vibration engine bay.

If the solenoid or pneumatic actuator has failed, replace it with a quality unit. A worn or leaking actuator will not hold the position the ECM commands, and mismatched aftermarket units often cause repeat codes. This is where sourcing the correct part matters.

For Garrett-equipped applications, the Garrett Pneumatic Actuator 757979-5102 is a direct-fit, precision-calibrated unit available from PT Turbo for $240.94. For larger Garrett frames requiring higher output, the Garrett Pneumatic Actuator 445963-0040 is in stock at $465.52.

Running a Mitsubishi turbo? We stock the Mitsubishi TD03 Pneumatic Actuator 49S3118761 for $104.33, and the Mitsubishi Pneumatic Actuator 4918918935 for $83.99. All of these are correctly calibrated so the actuator diaphragm and spring rate match factory boost targets.

If diagnosis reveals the turbo center section or VGT mechanism is also worn, you may be better served by a complete unit. Browse our remanufactured turbochargers, or if you want to keep your original housing and core, our turbocharger rebuild service restores it to spec.

New vs Remanufactured: What Makes Sense

Option	Cost	Best For	Warranty Confidence
New OEM actuator/solenoid	$$$	Fleets wanting maximum service life	Highest
Quality replacement actuator	$$	Most repairs, correct calibration	High
Remanufactured turbo	$$$	Worn core plus electrical fault	High, tested to spec
Rebuild your core	$$	Keeping a matched or hard-to-find unit	High

Preventing Repeat P0045 Codes

Once repaired, protect the circuit so it does not fail again. Route harnesses away from exhaust heat and secure them so they cannot chafe on brackets. Dielectric grease on connectors keeps moisture and corrosion out.

Keep an eye on related systems too. A clogged diesel particulate filter or a sticking EGR system can drive up backpressure and stress the boost control components, shortening actuator life.

Cross-Reference & Superseded Part Numbers

The turbochargers covered in this article match or supersede the following OEM and manufacturer part numbers. If you are searching by part number, these are the units stocked by PT Turbo for this application:

445963-151  •  448734-5  •  773326-0001  •  911984-5003S  •  953223-5001S  •  GTX2867R+Bolt-on+Turbo  •  GTX3071R+Bolt-on+Turbo  •  PTT-FIE-007  •  PTT-FIE-008  •  PTT-FIE-009  •  PTT-FIE-017  •  PTT-FIE-021  •  PTT-FIE-022  •  PTT-FIE-025  •  PTT-FIE-026  •  PTT-FOC-010  •  PTT-FOC-011  •  PTT-FOC-012  •  PTT-FOC-013  •  PTT-FOC-020  •  PTT-FOC-030  •  PTT-FOC-033  •  PTT-FOC-036  •  PTT-FOC-050  •  PTT-FOC-051  •  PTT-FOC-052  •  PTT-FOC-056  •  PTT-FOC-064  •  PTT-FOC-071  •  PTT-FOC-076  •  PTT-FOC-086  •  PTT-FOC-096  •  PTT-FOC-B11  •  PTT-FOC-B12  •  PTT-FOC-B15  •  PTT-FOC-B16  •  PTT-FOC-B17  •  PTT-FOC-B22  •  PTT-FOC-B24  •  PTT-HGC-004  •  PTT-HGC-069  •  PTT-HSG-405  •  PTT-MS3-003  •  PTT-MS3-007  •  PTT-MUS-005  •  PTT-MUS-010  •  PTT-RB2-002  •  PTT-SR2-002  •  PTT-STC-001  •  PTT-SUB-096  •  PTT-SUB-100  •  PTT-SUB-105  •  PTT-TBO-002  •  PTT-TBO-023  •  PTT-TBO-066  •  PTT-TBO-107  •  PTT-TBO-345  •  PTT-TBO-450  •  PTT-TBO-592  •  PTT-TBO-602  •  PTT-TBO-763  •  PTT-TBO-764  •  PTT-TBO-770  •  PTT-TBO-818  •  PTT-TBO-841  •  PTT-TBO-846  •  PTT-TBO-847  •  PTT-TBO-849  •  PTT-TBO-889  •  PTT-TBO-965  •  PTT-TBO-B34  •  PTT-TBO-B35  •  PTT-TBO-C15  •  PTT-TBO-C16  •  PTT-TBO-F83  •  PTT-TBO-F84  •  PTT-TBO-J26  •  PTT-TBO-J57  •  PTT-TBO-N23  •  PTT-TBO-N24  •  PTT-TBO-R94  •  PTT-TBO-R95  •  PTT-VEVO-026  •  PTT-VEVO-158  •  PTT-VEVO-189  •  PTT-VEVO-200  •  PTT-VSRT-007  •  PTT-VVW-004  •  PTT-VVW-042  •  PTT-VVW-047  •  PTT-WGT-019  •  PTT-WGT-032  •  PTT-WGT-037  •  PTT-WGT-093  •  PTT-WGT-103  •  PTT-WGT-108  •  PTT-WGT-109  •  TIL-BOV-007  •  TIL-WGT-035  •  stock+location+fsi/tsi+option+3

Can’t find your number above? Contact PT Turbo — our team has been matching part numbers since 1978.