OBD-II Generic Error Code P0240: How to Fix It

Medium 1-2 hours Medium Severity Verified June 2026
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Error Code
P0240
Brand
OBD-II Generic
Product Type
automotive
Severity
Medium
DIY Difficulty
Medium
Estimated Fix Time
1-2 hours
Error code P0240 indicates that the engine control module (ECM) has detected a problem with the turbocharger boost sensor B circuit, specifically that the signal is out of the expected range. This can cause reduced engine power and poor fuel economy. This guide provides step-by-step instructions to diagnose and fix the issue.
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Tools You'll Need

How to Fix Error Code P0240

  1. Check for Additional Codes

  2. Inspect Boost Sensor B Connector and Wiring

    Engine must be off and cool before touching any components.

  3. Test Boost Sensor B Voltage

    Use proper multimeter settings to avoid short circuits.

  4. Inspect for Boost Leaks

    Do not perform a pressure test with the engine running. Use a smoke machine or compressed air carefully.

  5. Check Turbo Actuator and Wastegate Operation

    Some turbochargers may be hot even after the engine cools. Allow sufficient time.

  6. Replace Boost Sensor B if Faulty

Parts You May Need

Turbocharger Boost Sensor B
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Vacuum hose or intercooler pipe
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Turbocharger Boost Sensor B
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Vacuum hose or intercooler pipe
Check Price on Amazon
Turbocharger Boost Sensor B
Check Price on Amazon
Vacuum hose or intercooler pipe
Check Price on Amazon
Turbocharger Boost Sensor B
Check Price on Amazon
Vacuum hose or intercooler pipe
Check Price on Amazon
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When to Call a Professional

If you've checked all connections, sensor and wiring, and boost leaks, but the code returns, the issue may be a failing ECM or internal turbo problem. A professional mechanic with advanced diagnostic equipment can further diagnose the boost control circuit.

Frequently Asked Questions

Can I drive with a P0240 code?
It's not recommended. The vehicle may enter limp mode, reducing power and potentially causing damage to the turbo or engine if driven hard.
What causes P0240?
Common causes include a faulty boost pressure sensor, wiring issues, boost leaks, a stuck wastegate, or a malfunctioning turbo actuator.
Is P0240 the same as P0236?
No. P0236 refers to Turbocharger Boost Sensor A Circuit Range/Performance, while P0240 is for Turbocharger Boost Sensor B Circuit Range/Performance. They are different sensors.
How do I test a boost sensor?
With a multimeter, check for 5V reference voltage on the sensor's power pin and good ground. Monitor the signal voltage while applying vacuum; it should change smoothly. Compare readings to manufacturer specs.
Will clearing the code fix P0240?
Clearing the code may temporarily turn off the check engine light, but if the underlying issue is not fixed, the code will return.

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