P2591 – Turbocharger Boost Control Position Sensor “B” Circuit Range/Performance

System: Powertrain | Standard: ISO/SAE Controlled | Fault type: Range/Performance | Location: Designator B

Definition source: SAE J2012/J2012DA (industry standard)

P2591 indicates the powertrain control system has detected a range/performance problem in the Turbocharger Boost Control Position Sensor “B” circuit. In practical diagnostic terms, the sensor feedback is not behaving plausibly compared to what the control module expects for the current operating conditions and commands. This is a plausibility/correlation type fault, not automatic proof that the sensor or turbocharger hardware has failed. Because enable criteria, signal naming, and control strategies vary by vehicle, confirm the correct PID names, connector pinouts, and test conditions in the appropriate service information before diagnosis.

What Does P2591 Mean?

P2591 – Turbocharger Boost Control Position Sensor “B” Circuit Range/Performance means the control module determined the “B” boost control position sensor circuit is outside the expected operating range or is not performing plausibly. Under standardized DTC conventions, “range/performance” faults typically relate to signal plausibility, correlation, response time, or commanded-versus-actual agreement rather than a direct electrical open/short condition. In other words, the module is flagging that the position feedback (or the circuit behavior carrying it) does not match expected behavior for the operating state.

Quick Reference

• System: Powertrain
• Official meaning: Turbocharger Boost Control Position Sensor “B” Circuit Range/Performance
• Standard: ISO/SAE Controlled
• Fault type: Range/Performance
• Severity: The MIL may illuminate and the vehicle may enter reduced-power operation if boost control feedback is considered unreliable.

Symptoms

• MIL/Check Engine: Warning light illuminated, sometimes after a drive cycle or during higher load.
• Reduced power: Limited acceleration or torque reduction due to protective boost control strategies.
• Boost irregularity: Surging, inconsistent boost delivery, or hesitation during throttle changes.
• Driveability: Rough running under load, poor throttle response, or intermittent stumble when boost is requested.
• Limp mode: Fixed or capped boost command with noticeably lower performance.
• Fuel economy: Decreased efficiency if boost control is restricted or unstable.
• Transmission behavior: Altered shift feel or timing on some platforms due to reduced engine torque reporting.

Common Causes

• Damaged wiring harness to the turbocharger boost control position sensor “B” (chafing, heat damage, pinched sections)
• Poor connector condition at the sensor or control module (loose fit, corrosion, water intrusion, terminal push-out)
• High resistance in the sensor signal circuit or sensor return/ground circuit (spread terminals, partially broken conductors)
• Intermittent opens/shorts in the sensor circuits triggered by engine vibration or movement (unstable signal causing plausibility failure)
• Mechanical restriction or binding in the boost control mechanism preventing expected movement (commanded vs. actual mismatch)
• Turbocharger boost control actuator issues limiting travel or response (electrical or mechanical), resulting in implausible feedback
• Sensor “B” biased or out of calibration within electrical limits (range/performance rather than high/low)
• Control module software/calibration or learned value/adaptation issue (vehicle-specific; confirm service information before parts replacement)

Diagnosis Steps

Tools typically needed include a scan tool capable of reading live data and running actuator tests (if supported), a digital multimeter for circuit checks and voltage-drop testing, and appropriate back-probing leads. Access to wiring diagrams and connector pinouts for the specific vehicle is essential because circuit design varies by platform.

1. Confirm P2591 is present and record freeze-frame data. Check for related turbo/boost, actuator, reference voltage, or airflow DTCs and address them first if they can affect commanded boost control.
2. Review scan data for the Turbocharger Boost Control Position Sensor “B” feedback and the commanded/desired position (if available). Look for disagreement, delayed response, sticking, noisy signal behavior, or values that do not track command.
3. Clear codes and perform a controlled test while logging data to reproduce freeze-frame conditions. Range/performance faults are typically confirmed by correlation over time, not a single static measurement.
4. Perform a detailed visual inspection of the sensor/actuator connectors and harness routing. Check for heat exposure, chafing, oil contamination, poor routing, and signs of prior repair.
5. Perform a controlled wiggle test while monitoring the position feedback PID. If the value becomes noisy, spikes, or drops with movement, suspect terminal fit, intermittent opens, or high resistance in the harness or connectors.
6. Using service information, identify the sensor circuits (reference/supply, signal, and return/ground as applicable). Verify circuit stability key-on/engine-off and compare to specification.
7. Perform voltage-drop testing on the sensor return/ground path and any feed path under load (as specified). Excessive voltage drop can skew the signal enough to trigger a range/performance fault without setting a dedicated high/low code.
8. With circuits de-powered as directed, verify continuity between the sensor connector and the control module for each circuit and check for unintended shorts between circuits or to ground/power. Flex the harness during checks to catch intermittent faults.
9. If supported, run a turbo boost control actuator test and observe whether feedback follows command smoothly through its travel. A persistent mismatch suggests mechanical restriction, actuator limitation, or biased sensor feedback.
10. If electrical integrity is verified, inspect the boost control mechanism for binding or restricted movement (vehicle-specific). Confirm it can move through its expected range and returns consistently.
11. Only after verifying wiring, connectors, circuit integrity, and mechanism movement should you consider component replacement (sensor “B”, actuator assembly, or module). Follow service information for required calibration or relearn procedures after repairs.

Professional tip: Range/performance faults are correlation problems. Log commanded position and sensor “B” feedback together during the operating conditions that set the code. Confirm the relationship is restored after each correction before replacing major components.

Possible Fixes & Repair Costs

Repair cost varies because the root cause can be a simple terminal issue, a harness fault, a sensor bias problem, or a mechanical actuator restriction. Accurate test-driven diagnosis helps avoid unnecessary parts replacement.

• Repair or replace damaged wiring between the boost control position sensor “B” and the control module
• Clean, reseat, or replace connectors/terminals with poor fit, corrosion, moisture intrusion, or fretting
• Repair power/ground issues identified by voltage-drop testing (feeds, grounds, splices, terminals)
• Replace the boost control position sensor “B” only after confirming biased/stuck output or failed correlation with verified-good circuits
• Repair or replace the boost control actuator or linkage if binding, sticking, or limited travel is confirmed
• Address intake/boost plumbing leaks or restrictions that cause implausible control response (vehicle-dependent)
• Update or reprogram control module software only if service information identifies a calibration strategy issue and electrical/mechanical integrity is confirmed
• Clear codes and complete the specified verification procedure to confirm the fault does not return

Can I Still Drive With P2591?

You may be able to drive short distances, but the risk depends on how the vehicle responds. A range/performance fault can trigger reduced power, limited boost, or inconsistent throttle response, which can be unsafe during merging or passing. If you experience severe power loss, abnormal noises, heavy smoke, stalling, or warnings affecting braking or steering, do not continue driving and arrange diagnosis and repair. If symptoms are mild, drive conservatively and avoid high load until the issue is verified.

What Happens If You Ignore P2591?

Ignoring P2591 can lead to recurring reduced-power events, poor drivability, and reduced fuel economy as the control system limits boost to protect the engine. If the cause is wiring degradation or a sticking mechanism, the condition may worsen and lead to frequent limp mode and additional turbo/airflow-related DTCs. Continued operation with unstable boost control may increase exhaust temperatures and stress related components depending on vehicle strategy.

Related Sensor Turbocharger Codes

Compare nearby sensor turbocharger trouble codes with similar definitions, fault patterns, and diagnostic paths.

• P2563 – Turbocharger Boost Control Position Sensor Circuit Range/Performance
• P2599 – Turbocharger Boost Control Position Sensor Circuit Range/Performance
• P2566 – Turbocharger Boost Control Position Sensor Circuit Intermittent
• P2565 – Turbocharger Boost Control Position Sensor Circuit High
• P2564 – Turbocharger Boost Control Position Sensor Circuit Low
• P2562 – Turbocharger Boost Control Position Sensor Circuit

Key Takeaways

• P2591 indicates a range/performance plausibility issue in the turbocharger boost control position sensor “B” circuit, not automatically a failed turbocharger.
• Diagnosis should focus on commanded vs. actual correlation, signal stability, and connector/circuit integrity.
• Start with wiring/connector inspection and voltage-drop testing before replacing sensors or actuators.
• Reduced power is possible; driving safety depends on severity and vehicle behavior.
• Repairs should be based on test evidence and verified with a proper road test and data logging.

Vehicles Commonly Affected by P2591

• Turbocharged engines using an electronic boost control actuator with position feedback
• Systems with a designated boost control position sensor “B” or multi-channel position sensing
• Applications with actuator/sensor mounting near high heat sources increasing connector and harness stress
• Platforms with complex intake/boost plumbing where leaks can affect control plausibility
• Vehicles frequently operated under high load or towing conditions increasing boost demand
• Engine bays with tight packaging leading to harness rubbing, pinching, or fatigue
• Vehicles exposed to moisture, salt, or debris that accelerates connector corrosion
• Closed-loop boost control systems where small feedback errors can trigger plausibility faults

FAQ

Does P2591 mean the turbocharger is bad?

No. P2591 is a range/performance plausibility fault for the Turbocharger Boost Control Position Sensor “B” circuit. Causes include wiring/connector issues, sensor drift/bias, actuator response problems, or mechanical restriction. Confirm with testing before replacing parts.

What is the difference between a range/performance fault and a circuit high/low fault?

Range/performance faults are plausibility issues where the signal may exist but does not behave as expected (stuck, skewed, slow, noisy, or not tracking commanded position). Circuit high/low faults indicate the signal is electrically above or below its allowed threshold. P2591 requires correlation and response testing in addition to basic circuit checks.

Can a wiring problem set a range/performance code like P2591?

Yes. High resistance, intermittent terminal contact, corrosion, or harness movement can distort the signal or delay response without producing a hard open/short code. This is why wiggle testing and voltage-drop testing are important.

Will clearing the code fix P2591?

No. Clearing resets stored fault data but does not correct the underlying condition. If the cause remains, P2591 will return when the enabling conditions repeat.

What should I check first when P2591 appears?

Start with connector and harness inspection near the turbocharger for heat damage, rubbing, loose locking, and terminal fit issues. Then verify power/ground integrity using voltage-drop testing. Next, use scan data to compare commanded versus actual position feedback during a controlled test to identify whether the issue is electrical integrity, sensor bias, actuator response, or mechanical restriction.

After repairs, verify the fix by clearing codes, completing the required drive cycle, and confirming stable, plausible feedback across the operating conditions that originally triggered the DTC.