OBD-II Code · Sensors
P0240
Turbocharger Boost Sensor "B" Range/Performance
Severity
medium
Worth booking. It costs fuel, emissions or comfort until it is fixed.
Can you drive it
Only if running normally
A short trip to a shop may be reasonable if the light is steady and the car runs normally. Stop safely for a flashing light, severe shaking, overheating, loss of power, or another urgent warning. The code alone cannot confirm safety.
Indicative cost (USD)
$100–$500
Varies by vehicle, diagnosis, parts, and local labor. This is not a repair quote.
Boost sensor B reading out of expected range.
How a shop works this
Work from evidence to part, not the other way round. A code names a circuit or a symptom; it does not name the part that failed.
Note every code that is set, not just this one.
Codes that appear together usually narrow the cause faster than any one of them read alone.
Read the freeze frame — the conditions the fault was recorded under.
Cold or warm, idle or load, road speed and engine speed. A fault that only appears cold is a different fault from one that only appears under load, even with the same code on the scanner.
Confirm the fault is current rather than history.
Clear the code and see whether it returns under those same conditions. A code that does not come back may have been logged during a repair, a flat battery, or a bad connection that has since been disturbed.
Then work the likely-causes list in the order shown.
That order is what a shop checks first for this code — wiring and connections before the component they run to, because a connector costs nothing to inspect and is a common answer.
If the code comes back after a repair, the underlying fault is still there. That is the point to bring in a scanner with live data and freeze-frame, or a shop that has one.
Common symptoms
- Check engine light
- Limp mode under load
Likely causes
- Failed sensorMost common
- Hose disconnected
- Wiring
Read the full diagnostic procedureP0240 indicates the turbocharger boost sensor B circuit is reporting values outside the expected range or failing to track manifold pressure changes…
P0240 indicates the turbocharger boost sensor B circuit is reporting values outside the expected range or failing to track manifold pressure changes correlative with engine load.
Start with the cheapest checks
inspect the boost pressure sensor connector for oil contamination from a leaking turbo seal (a $0 visual that catches roughly a third of these), then back-probe the 5V reference and ground at the sensor while watching for a clean signal voltage that should idle around 1.0-1.5V at atmospheric pressure and climb to 2.5-4.5V under boost; flat-lined signals stuck at 0.5V or 4.9V indicate sensor or wiring failure. Compare scan-tool MAP/boost PID against a known-good gauge on a T-fitting before condemning anything, because the expensive misdiagnosis here is replacing the turbocharger ($1,800-$3,500) when a $45 sensor or a cracked charge pipe was the actual fault.
Vehicle-specific patterns2011-2016 Ford F-150 3.5L EcoBoost commonly suffers MAP sensor contamination from PCV oil mist, addressed in TSB 14-0194; 2009-2014 VW/Audi 2.0T TSI…
- 2011-2016Ford F-150 3.5L EcoBoost commonly suffers MAP sensor contamination from PCV oil mist, addressed in TSB 14-0194;
- 2009-2014VW/Audi 2.0T TSI engines (EA888) crack the charge-pipe-to-throttle-body PCV fitting causing intermittent P0240 alongside lean codes;
- 2007-2013BMW N54/N55 throw P0240 when the charge pipe splits at the wastegate-side coupling;
- 2013-2018Chevrolet Cruze 1.4L turbo develops cracked intake manifold integrated with the PCV diaphragm.
Estimated repair$80 to $650.
Look up another code
P0240 — frequently asked
What does a P0240 code mean?
Boost sensor B reading out of expected range.
What causes a P0240 code?
Common causes: Failed sensor; Hose disconnected; Wiring.
What are the symptoms of a P0240 code?
Typical symptoms: Check engine light; Limp mode under load.
Is it safe to drive with a P0240 code?
Only if running normally. A short trip to a shop may be reasonable if the light is steady and the car runs normally. Stop safely for a flashing light, severe shaking, overheating, loss of power, or another urgent warning. The code alone cannot confirm safety. Estimated repair: $100-$500.
How do I diagnose a P0240 code?
Work from evidence to part, not the other way round. A code names a circuit or a symptom; it does not name the part that failed. 1. Note every code that is set, not just this one. 2. Read the freeze frame — the conditions the fault was recorded under. 3. Confirm the fault is current rather than history. 4. Then work the likely-causes list in the order shown.
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