P0240 – Turbo/Super Charger Boost Sensor “B” Circuit Range/Performance

P0240 is a turbocharger/supercharger boost sensor range/performance code that can leave you wondering if your engine or turbo is about to fail. This code usually means the ECU is seeing boost pressure data that doesn’t match what it expects for the driving conditions. Sometimes it’s a simple sensor or hose issue; other times it points to a worn turbo or boost control problem. In this guide, you’ll learn what P0240 means, common symptoms, how to diagnose it at home, when to seek a shop, and what repairs typically cost.

What Does P0240 Mean?

P0240 is an OBD-II diagnostic trouble code that generally translates to a “Turbocharger/Supercharger Boost Sensor B Range/Performance” problem. Exact wording varies by manufacturer, but the idea is the same: the ECU is not happy with the signal it’s getting from one of the boost pressure sensors compared to expected boost levels.

The ECU continuously compares requested boost vs. actual boost. If the sensor “B” signal is out of the expected range, lagging, or inconsistent for a set period, it flags P0240. This can be caused by a faulty sensor, wiring issues, air leaks, or an actual turbocharger or wastegate problem.

Quick Reference

• Code: P0240
• Meaning: Turbocharger/Supercharger Boost Sensor B Range/Performance
• Severity: Moderate to high, depending on boost loss or overboost
• Common Symptoms: Low power, limp mode, check engine light, poor acceleration
• Typical Causes: Boost sensor faults, boost leaks, wastegate or turbo issues

Real-World Example / Field Notes

In the shop, I see P0240 most often on turbocharged vehicles that are a few years into their life or have been tuned. A common scenario: a customer complains of “no power and loud whooshing.” Scan shows P0240, and a quick smoke test reveals a split intercooler hose. Another case: a tuned car with an aftermarket boost controller where the ECU’s requested boost and actual boost don’t match, triggering P0240. I’ve also seen corroded boost sensor connectors cause intermittent codes that only appear in wet weather.

Symptoms of P0240

• Check engine light: The MIL illuminates and P0240 is stored, sometimes with other boost-related codes.
• Low power: Noticeable loss of acceleration, especially under heavy throttle or on hills.
• Limp mode: The ECU may limit boost and throttle response to protect the engine and turbo.
• Poor fuel economy: Increased fuel consumption due to inefficient boost control and compensating fueling.
• Unusual turbo noises: Whistling, hissing, or whooshing from leaks, or whining from a failing turbo.
• Rough running: Hesitation or surging as boost fluctuates or the ECU cuts power.
• Black or gray smoke: Exhaust smoke under load if the turbo or fueling is not matched to boost.

Common Causes of P0240

Most Common Causes

• Faulty boost pressure sensor (sensor B): Internal failure, contamination with oil, or drifted calibration causing incorrect voltage output to the ECU.
• Boost leaks: Cracked intercooler, loose clamps, split hoses, or leaking charge pipes causing actual boost to be lower than commanded.
• Wastegate or boost control solenoid issues: Sticking wastegate, failed vacuum/pressure actuator, or bad boost control solenoid leading to underboost or overboost.
• Wiring or connector faults: Corroded terminals, broken wires, or poor grounds at the boost sensor circuit causing intermittent or incorrect readings.
• Aftermarket tuning or modifications: Aggressive tunes, manual boost controllers, or mismatched parts causing the ECU’s expected boost map to no longer match reality.

Less Common Causes

• Failing turbocharger: Worn bearings, damaged compressor wheel, or excessive shaft play reducing the turbo’s ability to build and hold boost.
• Restricted intake or exhaust: Clogged air filter, collapsed intake hose, or restricted catalytic converter affecting boost dynamics and sensor readings.
• ECU software or calibration issues: Rare, but sometimes fixed with a dealer reflash when known by the manufacturer.
• Vacuum/pressure line problems: Cracked or misrouted lines to the wastegate actuator or boost control solenoid altering boost control behavior.
• Barometric/MAF sensor correlation issues: If MAF or barometric readings are off, the ECU may think the boost sensor is out of range and set P0240.

Diagnosis: Step-by-Step Guide

Before you start, you’ll want a basic scan tool that can read live data, a digital multimeter, and ideally a smoke machine or pressure tester for boost leaks. A hand vacuum/pressure pump is helpful for testing wastegate actuators. Having access to factory service data or wiring diagrams for your specific vehicle is a big plus.

1. Confirm the code and check for companions. Scan for P0240 and note any related codes such as underboost, overboost, or sensor circuit faults. Multiple codes help narrow the direction.
2. Inspect visible boost plumbing. With the engine off, inspect intercooler hoses, clamps, and charge pipes for cracks, oil residue at joints, or loose fittings. Pay close attention to plastic end tanks and couplers.
3. Check the boost pressure sensor and connector. Locate sensor “B” (often on the intercooler pipe, intake manifold, or near the throttle body). Look for oil saturation, broken clips, green corrosion, or bent pins at the connector.
4. Test sensor wiring. Using a multimeter and wiring diagram, verify 5V reference, good ground, and signal continuity from the sensor to the ECU. Wiggle the harness while monitoring voltage for drops or spikes.
5. Read live data for boost and MAP. With a capable scan tool, monitor boost pressure/MAP, MAF, and throttle position. Compare requested vs. actual boost under light and moderate acceleration. Large mismatches point to leaks or control issues.
6. Smoke or pressure test the intake/charge system. Pressurize the system (usually 5–15 psi) and look for smoke escaping at couplers, intercooler seams, and vacuum lines. Fix any leaks before moving on.
7. Check wastegate and boost control operation. Apply vacuum or pressure to the wastegate actuator and confirm smooth movement. Test the boost control solenoid for proper operation and correct hose routing.
8. Evaluate turbo condition. If accessible, remove the intake pipe and check turbo shaft play, damaged blades, or signs of oil ingestion. Excessive play or contact marks suggest a failing turbo.
9. Review Mode $06 data (if available). Some scan tools allow you to see test results for boost and MAP sensor rationality. This can confirm if the ECU is failing a specific boost sensor test.
10. Clear codes and road test. After repairs or adjustments, clear P0240 and perform a controlled road test, watching live boost data. Confirm the code does not return under typical driving conditions.

Pro tip: Don’t replace the turbo just because you see a boost code. In practice, boost leaks and sensor/wiring faults are far more common and much cheaper to fix than a turbocharger.

Possible Fixes & Repair Costs

The correct repair depends on what you find during diagnosis. In many cases, P0240 is resolved with relatively simple fixes like replacing a sensor or repairing a leak. More serious issues like a failing turbo or wastegate can get expensive. Typical repair costs vary by vehicle, labor rates, and parts quality.

• Replace boost pressure sensor: $100–$300 parts and labor, depending on access and OEM vs. aftermarket.
• Repair or replace intercooler/boost hoses: $50–$400, ranging from a simple clamp or hose to a new intercooler.
• Repair wiring/connector issues: $100–$350, more if the harness is buried or requires extensive tracing.
• Wastegate actuator or boost control solenoid replacement: $150–$500, depending on design and accessibility.
• Turbocharger replacement: $1,000–$3,000+ for parts and labor, higher on some diesel or performance applications.
• ECU reflash or update: $100–$250 at a dealer or specialty shop if a software update is required.

Factors that affect cost include whether you use OEM or aftermarket parts, how difficult components are to access, and whether additional parts (gaskets, lines, hardware) need replacement at the same time.

Can I Still Drive With P0240?

In many cases you can still drive with P0240, but you may notice reduced power or limp mode. If the issue is underboost from a small leak or sensor problem, the main risk is poor performance and fuel economy. However, if the problem causes overboost, you risk serious engine or turbo damage. If you hear loud whining, grinding, or see heavy smoke, avoid driving and have the vehicle towed. For safety and long-term reliability, you should treat P0240 as something to address soon, not months down the road.

What Happens If You Ignore P0240?

Ignoring P0240 can turn a minor issue into a major repair. Prolonged driving with incorrect boost control can overwork the turbo, stress pistons and head gaskets, and foul the catalytic converter. You may also end up with chronic limp mode, poor fuel economy, and additional trouble codes. Fixing the root cause early is almost always cheaper than waiting until the turbo or engine suffers damage.

Last updated: February 13, 2026

Vehicles Commonly Affected by P0240

P0240 is most common on turbocharged gasoline and diesel vehicles. You’ll often see it on Volkswagen and Audi 1.8T/2.0T engines, Ford EcoBoost models, Subaru turbo boxers, GM turbocharged four-cylinders, and various BMW and Mercedes-Benz turbo engines. Many modern diesel pickups and SUVs, such as Ford Power Stroke, Ram Cummins, and GM Duramax, can also set P0240 when boost control or sensor issues arise. Any turbocharged or supercharged vehicle with multiple boost/MAP sensors has the potential to trigger this code when things aren’t working correctly.