P0240: Turbocharger/Supercharger Boost Sensor B Circuit Range/Performance
What to do
Expect reduced power. Ask for both boost sensors to be compared on live data — a difference between them localises the fault to one side.
What this code means
The second boost sensor is electrically valid but implausible. On twin-turbo engines, comparing what the two sensors report is itself diagnostic: one turbocharger producing markedly less boost than the other points at that unit's wastegate or a leak on that side rather than at either sensor.
Likely causes
Start here
- Boost leak in charge pipework · moderate
- Faulty boost pressure sensor · moderate
- Blocked or failing intercooler · moderate
Less common
- Faulty wastegate actuator · moderate
- Worn turbocharger · specialist
Symptoms
Components involved
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
Be the first to write this up
Nothing posted about this yet. Whatever you found is worth writing down — even a dead end saves someone the same afternoon.
What makes one worth reading:
- The car — make, model, year and engine. The same fault behaves differently on each.
- What you measured, not only what you replaced.
- What actually fixed it — or that nothing did, which is worth knowing too.
Sign in or create an account to add what you found about P0240.