P0240 is a generic OBD-II trouble code that indicates a range or performance problem with the Turbocharger/Supercharger Boost Sensor B circuit. The ECM/PCM has detected a sensor signal that does not match the expected pressure or operating conditions.
What Does P0240 Mean?
P0240 means the Engine Control Module (ECM) or Powertrain Control Module (PCM) has detected an incorrect or implausible signal from Boost Sensor B.
The boost sensor measures pressure in the turbocharger or supercharger system and sends a corresponding voltage signal to the ECM/PCM. When the signal does not correspond correctly with engine operating conditions, the module can store P0240 and illuminate the Check Engine Light.
The exact location, sensor configuration, and terminology can vary between vehicle manufacturers and engine designs.
Symptoms of P0240
- Check Engine Light.
- Reduced engine power.
- Slow or poor acceleration.
- Engine hesitation.
- Unstable boost pressure.
- Turbocharger or supercharger performance problems.
- Limp mode.
- Poor fuel economy.
- Abnormal boost pressure readings on a scan tool.
Common Causes of P0240
- Faulty Turbocharger/Supercharger Boost Sensor B.
- Sensor signal outside the expected range.
- Open or shorted sensor signal circuit.
- Incorrect reference voltage.
- Poor sensor ground.
- Loose, damaged, or corroded connector terminals.
- Damaged boost pressure hose or passage.
- Boost pressure leak.
- Turbocharger or supercharger control problems.
- ECM/PCM fault in rare cases.
Can I Drive with P0240?
You may be able to drive the vehicle for a short distance if it is operating normally. However, continued driving is not recommended if there is severe power loss, excessive boost, unusual turbocharger noise, heavy smoke, or limp mode.
An incorrect boost pressure signal can cause improper engine boost control. Avoid heavy acceleration until the fault is diagnosed.
How to Fix P0240
The correct repair depends on the cause of the code. Possible repairs include:
- Replace a defective Boost Sensor B.
- Repair damaged or broken wiring.
- Repair loose or corroded connector terminals.
- Repair damaged boost pressure hoses.
- Correct reference voltage problems.
- Repair the sensor ground circuit.
- Repair an open or shorted signal circuit.
- Repair boost leaks when applicable.
- Repair turbocharger or supercharger control faults.
- Clear the code and perform a road test after the repair.
Common Repair Mistakes
- Replacing the sensor without testing its signal circuit.
- Ignoring damaged or corroded connectors.
- Assuming the turbocharger is defective without testing it.
- Failing to verify reference voltage and ground.
- Ignoring boost pressure leaks.
- Using incorrect sensor pinout information.
- Failing to compare sensor readings with actual boost conditions.
P0240 Repair Cost
The repair cost depends on the vehicle, labor rate, parts required, and the actual cause of the fault.
A wiring or connector repair may cost relatively little, while replacing the boost sensor or repairing turbocharger control components can be more expensive.
Proper diagnosis should be performed before replacing expensive components.
Technical Information
Where Is the P0240 Fault Located?
The fault is associated with the circuit and signal of Turbocharger/Supercharger Boost Sensor B.
Depending on the vehicle, the sensor may be located on the intake manifold, charge-air piping, turbocharger system, supercharger system, or another specified location.
Because manufacturers use different layouts, always confirm the exact sensor location using the vehicle-specific service information.
Component Responsible for P0240
The main component associated with P0240 is Boost Sensor B. However, the sensor itself is not necessarily defective.
The problem may also be caused by the signal wire, reference voltage circuit, ground circuit, connector, wiring harness, pressure hose, boost system, or ECM/PCM.
The exact sensor designation and system configuration can vary by manufacturer, so the manufacturer's wiring diagram should be used for accurate identification.
Signal Flow
Reference Voltage
Boost Sensor B
Boost Pressure
Sensor Signal
ECM / PCM
How to Diagnose P0240
- Connect an OBD-II scanner and confirm P0240.
- Check for additional turbocharger, supercharger, or boost-related codes.
- Locate Boost Sensor B using the vehicle-specific service information.
- Inspect the sensor connector and wiring.
- Look for corrosion, damaged terminals, broken wires, or melted insulation.
- Measure the sensor reference voltage according to manufacturer specifications.
- Test the sensor ground circuit.
- Measure the sensor signal voltage.
- Monitor the sensor data with a scan tool while engine conditions change.
- Compare the sensor reading with actual boost pressure.
- Inspect boost hoses and intake/charge-air components for leaks.
- If the sensor circuit is correct, inspect the turbocharger or supercharger control system.
- Repair the identified fault, clear the code, and perform a road test.
Related DTC Codes
Turbocharger/Supercharger Boost Sensor B Circuit
Turbocharger/Supercharger Boost Sensor B Circuit Low
Turbocharger/Supercharger Boost Sensor B Circuit High
Turbocharger/Supercharger Boost Sensor A Circuit Range/Performance
Common Questions About P0240
Does P0240 always mean the boost sensor is bad?
No. P0240 can be caused by wiring problems, connector damage, incorrect reference voltage, poor ground, boost leaks, pressure problems, or other faults in the boost sensing system.
Can P0240 cause limp mode?
Yes. Some vehicles may reduce engine power or enter limp mode when the ECM/PCM detects an unreliable or implausible boost pressure signal.
Can a boost leak cause P0240?
A boost leak can affect pressure readings and engine performance. However, the electrical sensor circuit should also be tested because P0240 specifically involves the range or performance of the Boost Sensor B signal.
What should I check first with P0240?
Start by checking the Boost Sensor B connector and wiring. Then verify the reference voltage, ground, and signal before replacing the sensor.