You can usually drive gently for short trips, but power will be down or the engine in limp mode and boost is uncontrolled. Avoid hard acceleration and hauling — an open solenoid can leave the wastegate defaulting closed and let boost spike. Fix it soon. P0045 means the powertrain control module detected an open (broken) electrical circuit at the turbocharger or supercharger boost-control solenoid — the valve that regulates how much boost the turbo makes. "Open" means the PCM sees no current flow through the solenoid, so it can no longer command boost and usually falls back to a reduced-power failsafe.
What P0045 means
On a boosted engine the PCM sets the boost limit by pulsing the boost-control (wastegate regulating valve) solenoid with a variable duty cycle. That solenoid meters pressure or vacuum to the wastegate actuator — on a gasoline turbo like Ford's 3.5L EcoBoost it is the turbocharger wastegate regulating valve solenoid feeding a pneumatic wastegate diaphragm, and on a variable-geometry diesel turbo it is the vane/boost-control solenoid that positions the turbine vanes. The solenoid runs on a simple two-wire circuit: a fused power feed on one side and the PCM's driver (control/ground side) on the other. P0045 sets when that circuit reads electrically OPEN — a broken wire, disconnected connector, or failed solenoid winding — so no current flows and the PCM's driver sees no load. This is the open-circuit member of the family and is distinct from P0046 (range/performance — the circuit works but boost doesn't track the command), P0047 (circuit low/short to ground), and P0048 (circuit high). With the solenoid dead the wastegate reverts to its spring-default position, so the PCM loses boost authority and typically pulls timing, caps torque, or drops into a reduced-power/limp mode to protect the engine.
Symptoms
- Check-engine light on, usually stored with boost-related freeze-frame data
- Clear loss of power, poor throttle response, or the engine dropping into limp/reduced-power mode
- Flat, sluggish acceleration under load — the turbo never spools to full boost
- On pressure-actuated wastegate systems, possible overboost spikes because the wastegate springs to its default (closed) position with the solenoid dead
- Reduced fuel economy, and on diesels sometimes reduced pulling power or altered throttle feel
Common causes
- Broken, chafed, or corroded wire in the solenoid control or power-feed circuit creating an open between the PCM and the solenoid
- Disconnected, loose, or corroded solenoid connector so the circuit never completes
- Failed boost-control / wastegate regulating valve solenoid with an open internal winding
- Blown fuse or open circuit-breaker feeding the solenoid's power side (Ford EcoBoost feeds it through a dedicated fuse)
- Damaged connector pins — spread, pushed-back, or contaminated terminals that lose contact
- Wiring harness damage from heat or rubbing near the hot turbo/exhaust area
- Failed PCM solenoid driver (uncommon — verify the wiring, connector, and solenoid first)
Severity & driving advice
Severity: Moderate — Drivable but expect reduced power or limp mode; with the wastegate at its spring default, pressure-actuated systems can also overboost, so repair soon.
Can I drive? You can usually drive gently for short trips, but power will be down or the engine in limp mode and boost is uncontrolled. Avoid hard acceleration and hauling — an open solenoid can leave the wastegate defaulting closed and let boost spike. Fix it soon.
Diagnostic approach
- Scan codes and read freeze-frame — Confirm P0045 and log any companion codes plus the RPM, load, and boost stored when it set. Note whether siblings P0046 (range/performance), P0047 (low), or P0048 (high) or overboost/underboost codes (P0234/P0299) are present, since they change the diagnostic path.
- Inspect the solenoid connector and harness — Because P0045 is an open circuit, start at the boost-control/wastegate solenoid connector. Check for a disconnected or loose plug, corroded or spread pins, and chafed or melted wiring in the run back to the PCM — the harness sits near the hot turbo, a common spot for open-circuit damage.
- Verify power and control wires — The solenoid uses a two-wire circuit — a fused/battery power feed on one pin and the PCM control (driver) on the other. Key-on, confirm the feed side has voltage (check the corresponding fuse or circuit breaker first) and that the control wire is continuous back to the PCM with no open.
- Measure the solenoid winding resistance — With the connector unplugged, measure resistance across the solenoid's two terminals. An open (infinite / OL) reading confirms a failed solenoid winding; a plausible reading (these PWM boost solenoids are typically low-resistance, often in the low tens of ohms — verify the exact value for the vehicle) points instead to the wiring or connector as the open.
- Check continuity and voltage-drop on each circuit — Do point-to-point continuity from the PCM connector to the solenoid connector on both the power and control wires to find the break. A wire that shows no continuity, or a large voltage drop under a load test, isolates the open segment or a high-resistance connection posing as an open.
- Command the solenoid and confirm operation — With the circuit repaired, use the scan tool's bidirectional test to cycle the boost-control solenoid and confirm it clicks and passes/blocks pressure or vacuum on command. On the EcoBoost, verify the wastegate actuator responds and holds its commanded position rather than sitting at the spring default.
- Clear and road-test under load — Erase P0045 and drive under boost while graphing commanded vs. actual boost. Confirm the turbo now builds and regulates boost, the code stays off, and the engine no longer drops into reduced-power mode.
FAQ
Is it safe to drive with a P0045 code?
For short, gentle trips usually yes, but the truck will likely be down on power or in a reduced-power/limp mode and the PCM can no longer regulate boost. On pressure-actuated wastegate systems the wastegate can spring to its default closed position with the solenoid dead, allowing boost to overshoot, so avoid hard acceleration and heavy loads and get it repaired soon.
What is the difference between P0045 and P0046, P0047, or P0048?
All four involve the same boost-control solenoid "A" circuit but describe different failure modes. P0045 is a circuit open — the PCM sees no current flow, meaning a broken wire, unplugged connector, or open solenoid winding. P0046 is range/performance (the circuit works but actual boost doesn't track the command), P0047 is circuit low/short to ground, and P0048 is circuit high. P0045 is the hard open-circuit fault.
What does the boost control solenoid do?
It's the PCM-controlled valve that sets how much boost the turbo makes. The module pulses it with a variable duty cycle; on a gasoline turbo like the EcoBoost it meters pressure or vacuum to the pneumatic wastegate actuator (the wastegate regulating valve solenoid), and on a variable-geometry diesel turbo it positions the turbine vanes. "A" designates the first boost-control solenoid, typically bank 1 or turbo 1 on a twin-turbo setup.
Can a wiring or connector problem alone set P0045?
Yes — that is the most common cause. Because P0045 specifically flags an open circuit, a broken or chafed wire, a disconnected or corroded connector, or a blown fuse on the solenoid's power feed will set it even when the solenoid itself is fine. Inspect and test the connector and both wires back to the PCM before replacing the solenoid.
Does P0045 mean I need a new turbocharger?
Usually not. The fault is in the boost-control solenoid's electrical circuit — the wiring, connector, fuse, or the solenoid winding — not the turbo cartridge. Diagnose the open circuit and the solenoid first; the turbocharger itself is rarely the cause of P0045.