P2391 – Turbocharger Boost Sensor Control Intermittent

System: Powertrain | Standard: ISO/SAE Controlled | Fault type: General

Definition source: SAE J2012/J2012DA (industry standard)

P2391 indicates the powertrain control module has detected an intermittent problem with turbocharger boost sensor control. “Intermittent” means the fault is not consistently present and may appear and disappear based on vibration, heat, moisture, connector movement, or changing electrical load. The code points to an electrical/signal integrity concern involving the boost sensor control path rather than confirming a mechanical turbocharger problem by itself. Because wiring layouts, sensor types, and monitoring logic vary by vehicle, confirm the exact circuit description, pinouts, and test specifications in the applicable service information before beginning repairs.

What Does P2391 Mean?

P2391 – Turbocharger Boost Sensor Control Intermittent means the control system has observed an intermittent interruption or instability related to turbocharger boost sensor control. In practical terms, the expected boost-sensor-related control signal (or its associated electrical path) is sometimes valid and sometimes not, causing the module to flag an intermittent condition rather than a steady “high,” “low,” or “open” fault. SAE J2012 defines the general structure of DTCs, but the exact monitored signal, enabling conditions, and confirmation strategy for “intermittent” detection depend on the vehicle’s design and should be verified with service information.

Quick Reference

• System: Powertrain
• Official meaning: Turbocharger Boost Sensor Control Intermittent
• Standard: ISO/SAE controlled
• Fault type: Circuit Intermittent
• Severity: MIL may illuminate and intermittent boost control issues can cause fluctuating power delivery and reduced drivability depending on operating conditions.

Symptoms

• MIL/Check engine light: Lamp may be on, or may come and go as the intermittent condition appears and clears.
• Reduced power: Intermittent boost-related control faults can trigger momentary torque limiting or reduced power behavior.
• Surging: Power may fluctuate during acceleration as the signal drops out and recovers.
• Hesitation: Brief stumble or delay on throttle application, especially under load.
• Inconsistent boost response: Boost may feel normal at times and weak at others without a consistent pattern.
• Abnormal shift feel: Some vehicles may alter shift strategy when engine torque calculation becomes unstable.
• Intermittent drivability complaint: Symptoms may be more noticeable with vibration, bumps, heat soak, or wet conditions.

Common Causes

• Connector intermittency at the boost sensor: Loose terminal tension, poor pin fit, minor corrosion, or an incompletely seated connector that momentarily interrupts the signal or reference.
• Harness damage near hot/moving parts: Chafed insulation, heat damage, or rub-through causing momentary opens/shorts as the engine moves or under vibration.
• Poor ground integrity: Shared sensor ground with high resistance, loose ground fastener, or corrosion creating intermittent signal drift or dropouts.
• Reference voltage instability: Intermittent loss of sensor feed or reference due to wiring faults, connector issues, or an internal control-module driver issue (varies by vehicle).
• Signal circuit intermittency: Intermittent open/high resistance in the signal wire, intermittent short to ground/power, or moisture intrusion affecting the signal path.
• Boost pressure sensor fault: Internal sensor intermittency causing brief dropouts or spikes without a consistent hard failure.
• Control module/ECU connection issue: Connector pin fretting, water intrusion, or poor terminal contact at the module leading to intermittent sensor interpretation (varies by vehicle).
• Aftermarket wiring alterations: Splices, add-on modules, or repairs with poor crimping/soldering that become intermittent with temperature and vibration.

Diagnosis Steps

Tools you may need include a scan tool capable of live data and data logging, a digital multimeter, back-probing leads, and basic hand tools for connector inspection. A wiring diagram and the vehicle’s service information are essential for identifying the correct sensor pins, shared grounds, and expected signal behavior. If available, use an oscilloscope for capturing brief dropouts that a meter may miss.

1. Confirm the complaint and capture code data: Verify P2391 is present and record freeze-frame data, engine load, RPM, and conditions when the fault set. Note whether the code is current or history/intermittent.
2. Check for related DTCs: Scan all modules and address other powertrain codes that could affect boost sensing or reference/ground stability. Diagnose shared power/ground or reference faults first if present.
3. Review live data for plausibility and dropouts: Monitor the turbocharger boost sensor parameter(s) at idle and during a controlled road test or snap-throttle (as appropriate). Look for brief spikes, drop-to-zero, or erratic behavior that matches an intermittent condition.
4. Perform a focused visual inspection: Inspect the boost sensor connector, harness routing, and nearby components. Look for oil saturation, water intrusion, broken locks, pulled wires, abrasion points, and evidence of contact with hot surfaces or sharp edges.
5. Connector and terminal checks: With ignition off, disconnect the sensor and inspect terminals for spread pins, corrosion, or push-outs. Confirm the connector fully seats and locks. If service information allows, perform terminal drag/tension checks using the correct test probes.
6. Wiggle test while watching live data: With the engine running (or key on if specified), gently manipulate the harness and connector at the sensor and along the routing toward the module. Watch live data and the MIL/status for momentary changes. Repeat under similar vibration/temperature conditions if possible.
7. Power/ground circuit integrity testing: Using the wiring diagram, verify the sensor feed/reference and ground integrity. Use voltage-drop testing on the ground path under load where possible, and check for intermittent opens by flexing the harness while monitoring meter readings.
8. Signal circuit checks for intermittency: Test the signal wire for continuity and for shorts to ground or power per service information. Focus on areas where the harness bends or passes through retainers. If available, use a scope to capture brief signal dropouts during a wiggle test.
9. Check module-side connections (varies by vehicle): If the sensor and local harness appear sound, inspect the control module connector(s) for pin fit, moisture, or fretting. Verify grounds and reference feeds shared by other sensors to identify a broader intermittent supply/ground issue.
10. Verify the repair with logging: After correcting the identified cause, clear codes and perform a monitored drive cycle while data logging the boost sensor parameter. Confirm no dropouts occur and that P2391 does not return under similar conditions.

Professional tip: Intermittent faults are easiest to confirm by reproducing the exact conditions in the freeze-frame data. Use live-data logging and a gentle harness manipulation routine (sensor connector, first 12–18 inches of harness, then module-side routing) to pinpoint where the signal becomes unstable, and avoid forcing probes that can spread terminals and create new intermittents.

Possible Fixes & Repair Costs

Repair costs for P2391 vary widely because an intermittent turbocharger boost sensor control issue can be caused by anything from minor connector problems to component replacement. Total cost depends on confirmed root cause, required parts, labor time, and whether additional wiring repairs are needed.

• Repair wiring/terminals: Restore damaged wiring, poor pin fit, fretting, or corrosion found at the boost sensor or related harness.
• Clean and secure connectors: Remove contamination, correct terminal tension, and ensure connectors are fully seated and locked.
• Restore power/ground integrity: Correct excessive resistance or intermittent opens found during voltage-drop testing on sensor supply and ground paths (as applicable by vehicle).
• Repair harness routing issues: Re-route, re-loom, and protect wiring where chafing, heat damage, or vibration strain causes intermittent signal disruption.
• Replace the turbocharger boost sensor: Replace only after testing confirms the sensor output is intermittently erratic and not caused by the circuit or connector.
• Address control/actuator-related faults: If the vehicle design uses a separate control module or actuator influencing boost sensing/control, repair or replace only when proven by test results.

Can I Still Drive With P2391?

You may be able to drive short distances if the vehicle feels normal, but an intermittent boost sensor control fault can trigger reduced power, unstable acceleration, or a warning light that comes and goes. If you experience severe hesitation, limp mode, stalling, unusual noises, or any brake/steering warnings, do not continue driving; have the vehicle inspected and confirm the fault with service information and scan data.

What Happens If You Ignore P2391?

Ignoring P2391 can lead to recurring drivability issues and intermittent reduced-power operation as the engine control system reacts to an unreliable boost-related signal. Over time, repeated fault events can mask other problems, complicate diagnosis, increase the chance of poor fuel economy, and may contribute to operating conditions the engine control system is trying to avoid.

Last updated: February 16, 2026

Vehicles Commonly Affected by P2391

• Turbocharged gasoline engines: Vehicles using boost pressure feedback for engine load and turbo control.
• Turbocharged diesel engines: Applications where boost monitoring is central to fueling and airflow control.
• Vehicles with high underhood heat: Platforms where heat exposure can degrade insulation and connectors near turbo plumbing.
• High-vibration applications: Vehicles where harness movement can intermittently disturb terminals or chafed wiring.
• Vehicles with recent engine bay work: Repairs that may leave connectors partially seated or wiring routed incorrectly.
• Higher-mileage vehicles: Aging harnesses and terminal tension loss can contribute to intermittent signal behavior.
• Vehicles exposed to moisture/road debris: Environmental intrusion can promote corrosion at sensor connectors and splices.
• Vehicles with modified intake/charge piping: Non-standard routing or tension on harnesses may increase intermittent connection issues.

For best results, document the exact conditions that set P2391 (temperature, load, road speed, and harness movement) and use the same conditions during verification to ensure the intermittent fault is truly resolved.