P2387 – Turbocharger Boost Sensor A/B Correlation (Alternate)

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

Definition source: SAE J2012/J2012DA (industry standard)

P2387 is a powertrain diagnostic trouble code that indicates a correlation problem between two turbocharger boost pressure sensor signals identified as Sensor A and Sensor B. In practical terms, the control module has detected that the two reported boost values do not agree with each other in a way it considers plausible, based on its internal comparison logic. Because sensor locations, naming conventions, and the exact enable criteria vary by vehicle, confirm the affected sensors, connectors, and test conditions in the appropriate service information before testing or replacing parts.

What Does P2387 Mean?

P2387 – Turbocharger Boost Sensor A/B Correlation (Alternate) means the powertrain control module has detected that the signals from two boost-related sensors (labeled A and B) do not correlate as expected. This is a plausibility/correlation fault rather than a simple “high” or “low” electrical input code. Under operating conditions defined by the manufacturer (varies by vehicle), the module compares the two sensor inputs for agreement and sets the code when the relationship between them is outside the allowable window for too long or too often. SAE J2012 defines the standardized structure used to identify DTCs such as this one.

Quick Reference

• System: Powertrain
• Official meaning: Turbocharger Boost Sensor A/B Correlation (Alternate)
• Standard: ISO/SAE controlled
• Fault type: Plausibility (correlation)
• Severity: MIL illumination is possible, and the vehicle may enter reduced-power operation if boost control plausibility cannot be confirmed.

Symptoms

• MIL/Check engine: Warning light illuminated, sometimes after a repeat drive cycle.
• Reduced power: Limited acceleration or a torque-reduction strategy under load.
• Boost inconsistency: Surging, uneven power delivery, or unexpected boost behavior during throttle changes.
• Hesitation: Delay in response when accelerating, especially in mid-range load conditions.
• Limp mode: Protective strategy that limits boost or throttle to prevent unreliable control.
• Poor fuel economy: Increased consumption if boost control is constrained or fueling is adjusted.
• Driveability fluctuation: Intermittent symptom changes as the correlation check passes/fails under different conditions.

Common Causes

• Connector issues at boost sensors: Loose fit, corrosion, moisture intrusion, terminal fretting, or bent pins at either sensor A or sensor B causing skewed signals.
• Harness damage: Chafed, pinched, heat-damaged, or oil-soaked wiring to one sensor creating intermittent resistance changes and correlation errors.
• Shared reference/return faults: A disturbed 5V reference or sensor ground shared by both sensors (or nearby sensors) shifting both readings but not equally.
• Signal circuit high resistance: Partial breaks, poor crimps, or internal conductor damage causing a slow or offset signal that fails correlation checks under changing boost.
• Shorts between signal circuits: Cross-talk/short between sensor A and sensor B signal wires causing the two channels to track incorrectly or mirror each other.
• Sensor performance drift: One boost pressure sensor biased, slow to respond, or contaminated internally, producing a plausible-looking signal that no longer matches the companion sensor.
• Improper sensor installation: Wrong sealing, incorrect seating, damaged O-ring (varies by vehicle), or a restriction at the sensing port that delays one sensor’s response.
• Induction/charge-air plumbing issues affecting ports: Leaks, restrictions, or disconnected lines that cause one sensor to “see” different pressure than the other due to port location differences (varies by vehicle).
• Control module or calibration issue: Less common; an internal fault or incorrect programming can misinterpret otherwise valid signals after power/ground integrity is confirmed.

Diagnosis Steps

Tools that help: a scan tool with live-data graphing and DTC freeze-frame access, a multimeter for power/ground checks, and wiring diagrams/service information for pinouts and expected sensor behavior (varies by vehicle). A back-probing kit is recommended to avoid terminal damage. For intermittent faults, plan to road-test while logging data in a controlled, safe environment.

1. Confirm the code and capture data: Verify P2387 is active or stored. Record freeze-frame information and note any related boost, pressure, or sensor reference/ground DTCs that could affect correlation.
2. Review monitored parameters: In live data, identify which PIDs correspond to boost sensor A and boost sensor B. Confirm they are the correct channels and observe if one value is consistently offset, delayed, noisy, or drops out.
3. Visual inspection (key off): Inspect both sensor connectors and harness routing. Look for oil saturation, water intrusion, broken locks, exposed conductors, rub-through near brackets, and areas near heat sources that can create intermittent resistance.
4. Connector and terminal checks: Disconnect each sensor and inspect terminals for spread, corrosion, pushed-out pins, or poor retention. Lightly tug-test wires at the connector backshell. Repair terminal fit issues before deeper testing.
5. Check reference voltage and sensor ground integrity: With key on (engine off), verify the presence of the appropriate reference supply and a solid sensor ground at each connector using service information for pin identification. If either is missing or unstable, trace back to shared splices, grounds, and the module connector.
6. Voltage-drop test the ground and feed circuits: With the circuit loaded (engine running if required by service info), perform voltage-drop testing across the sensor ground path and reference/feed path to locate excessive resistance at splices, pins, or grounds. Repair the point of loss rather than replacing parts.
7. Signal circuit integrity tests: With sensors connected, back-probe and check for an erratic or pegged signal while gently manipulating the harness. With connectors unplugged (as appropriate), check for shorts to ground, shorts to power, and shorts between the A and B signal circuits; confirm continuity end-to-end per service info.
8. Wiggle test with live-data logging: Start a live-data recording of both sensor signals and perform a systematic wiggle test from each sensor toward the control module. A correlation fault often appears as a brief spike, dropout, or lag on only one channel.
9. Compare sensor response behavior: Under controlled conditions (snap throttle/steady load as appropriate and safe), graph both sensors together. Look for one sensor responding slower or showing damped changes compared to the other; correlation faults commonly show mismatch during transitions rather than steady-state.
10. Inspect sensing ports and plumbing (varies by vehicle): Check the physical pressure source to each sensor—ports, hoses, or passages—for restrictions, kinks, loose connections, or leaks that could cause one sensor to sample a different or delayed pressure.
11. Component substitution only after circuit proof: If wiring, power, and ground are proven good and the fault follows one sensor’s channel behavior, replace the verified suspect sensor and retest. If the issue does not follow the sensor, re-check harness faults or module-side connector issues.
12. Clear, drive cycle, and confirm: Clear codes, then repeat the operating conditions from freeze-frame while logging A/B signals. Confirm P2387 does not return and that both channels track correctly across changing boost demands.

Professional tip: Correlation codes are easiest to solve by graphing both channels on the same time scale and focusing on transitions (tip-in/tip-out) where lag, filtering, and intermittent opens show up. If the signals match at idle but separate under load, prioritize harness movement/heat-related faults and voltage-drop results over static resistance checks.

Possible Fixes & Repair Costs

Repair costs for P2387 vary widely because the code points to a sensor correlation problem that can be caused by wiring, connectors, sensor drift, installation issues, or intake/boost system faults. Confirm the root cause with testing before replacing parts or performing adjustments.

• Repair wiring faults: Restore damaged, stretched, oil-soaked, or heat-affected harness sections for the boost sensor A and boost sensor B signal, reference, and ground circuits as applicable.
• Clean/secure connectors: Address bent pins, poor terminal tension, corrosion, water intrusion, or partially seated connectors at both sensors and at the control module connection points (varies by vehicle).
• Correct sensor installation issues: Reseat sensors, repair mounting damage, replace missing seals, and ensure the sensor ports are not obstructed (design varies by vehicle).
• Replace the faulty sensor: Replace boost sensor A or boost sensor B only if testing shows one sensor is biased, slow to respond, intermittently dropping out, or otherwise not matching expected behavior.
• Address intake/boost leaks or restrictions: Repair leaks, loose clamps, split hoses, restrictions, or contamination that can cause the two boost-related readings to disagree under load (confirm with inspection/testing).
• Verify related components: If equipped, inspect/verify the charge air path and boost control hardware for conditions that can create unstable or inconsistent boost signals (varies by vehicle and system layout).

Can I Still Drive With P2387?

You may be able to drive short distances if the vehicle feels normal, but treat P2387 as a plausibility/correlation fault that can trigger reduced power and inconsistent boost control. If you experience severe power loss, surging, misfiring, stalling, abnormal noises, smoke, or any warning that affects braking/steering behavior, do not continue driving—stop safely and diagnose the cause.

What Happens If You Ignore P2387?

Ignoring P2387 can lead to recurring warning lights, reduced performance, unstable boost response, and increased stress on the turbocharging/air path as the control system compensates for signals it cannot trust. Prolonged operation without diagnosis may also mask a developing wiring or air leak issue that worsens over time.

Last updated: February 16, 2026

Vehicles Commonly Affected by P2387

• Turbocharged gasoline engines using two boost-related pressure inputs for plausibility checks.
• Turbocharged diesel engines that compare boost/charge pressure signals for control and diagnostics.
• Engines with separate sensors (for example, manifold pressure and charge pipe/boost pressure) where the control module correlates readings.
• Vehicles with complex charge-air routing where pressure drop across components can be monitored and cross-checked (layout varies by vehicle).
• High-mileage vehicles where sensor drift, connector wear, and harness fatigue are more likely.
• Vehicles operated in harsh environments that increase the chance of connector contamination, corrosion, or heat-related wiring damage.
• Vehicles with recent repairs involving intake plumbing, sensors, or wiring where a connector may be left loose or a hose misrouted.
• Vehicles with aftermarket modifications to the intake/charge system that can change pressure dynamics and sensor agreement.

If P2387 returns after repairs, re-check connector pin fit, harness routing near heat/vibration points, and live-data agreement between boost sensor A and B during the same drive conditions.