P0240🔧 Turbo/supercharger boost pressure sensingStop and fix promptly

P0240: Turbocharger/Supercharger Boost Sensor B Range/Performance (Meaning, Causes, Fixes)

Reviewed 2026-10-26 · Based on 2 cited source(s)

What P0240 means

A turbocharger is a pump driven by exhaust gas that pushes extra air into the engine, which is called boost. Per OBD-Codes.com, the powertrain control module (PCM) controls boost by opening a bypass called the wastegate, using a vacuum motor fed through a control solenoid, and it measures the result with a boost pressure sensor (Ford, VW) or a manifold absolute pressure (MAP) sensor (Chrysler, GM). P0240 is the sensor "B" code; engines with a second turbo or a second boost sensor use the B codes. The two sources describe it differently. OBD-Codes.com titles it Turbocharger Boost Sensor B Range/Performance and says it sets when measured pressure is greater than commanded pressure. RepairPal's page titles it Turbocharger/Supercharger Boost Sensor B Circuit (without Range/Performance, the same title it gives P0239) and says the PCM sets it when it detects an incorrect signal from the boost pressure sensor. Their cause lists also differ, as noted below. P0240 is the B-sensor counterpart of P0236 (sensor A range/performance). P0239 is the general circuit code for sensor B, and P0241 and P0242 are its circuit low and circuit high codes, per RepairPal's code list.

Severity: can I keep driving?

Stop and fix promptly

Get it checked soon and drive gently until you do. RepairPal rates P0240 Urgent, meaning immediate action is needed, and says the engine may go into limp home mode. OBD-Codes.com says it should be addressed as soon as possible because of the increased risk of overboost and catalytic converter damage.

Common symptoms

Likely causes

Roughly most to least common, based on the sources below. Your vehicle may differ.

  1. A problem with the vacuum supply, such as a faulty vacuum pump (OBD-Codes.com)
  2. Pinched, collapsed, cracked or broken vacuum lines (OBD-Codes.com)
  3. A faulty wastegate control solenoid (OBD-Codes.com)
  4. A wiring issue (RepairPal)
  5. A turbocharger or supercharger failure (RepairPal)
  6. An exhaust leak (RepairPal)
  7. A brake booster pressure sensor failure (RepairPal only)
  8. A faulty PCM (OBD-Codes.com, RepairPal)

Diagnostic steps you can do

⚠ Before you start

Work on a cool engine, parked on level ground with the parking brake set. Never work under a car supported only by a jack.

  1. Scan for other codes and check for technical service bulletins (TSBs) for your vehicle. OBD-Codes.com says your issue may be a known problem with a known fix.
  2. Inspect every vacuum line for kinks, pinches, cracks or breaks, not just the ones for wastegate control B. OBD-Codes.com says a big leak anywhere in the vacuum system can hurt the whole system.
  3. With a vacuum gauge, check for vacuum at the input side of the B control solenoid. OBD-Codes.com says no vacuum points to the vacuum pump.
  4. If vacuum is there, back-probe the solenoid's signal wire with a meter that reads duty cycle or frequency and drive the vehicle. OBD-Codes.com says a signal present points to the solenoid, and no signal points to the PCM.
  5. Look over the boost sensor wiring and connector and check for exhaust leaks, since RepairPal lists wiring and exhaust leaks as causes.

Typical fixes

Repair costs vary widely by vehicle, region, parts brand and shop, so we don't quote prices. Get a written estimate after diagnosis.

🛠 When to call a pro

  • The engine is in limp mode or has very low power
  • You hear new turbo noises or see heavy smoke
  • You don't have a vacuum gauge or a meter that reads duty cycle
  • The vacuum lines and solenoid check out and the code comes back
  • A PCM fault is suspected

Where to buy

Plain search links. Always match parts to your exact year, make, model and engine.

OBD2 scanners on Amazon Parts at Advance Auto Parts catalog at RockAuto

FAQs

Can I drive with a P0240 code?

Only gently and not for long. RepairPal rates it Urgent and says the engine may go into limp mode, and OBD-Codes.com says it should be addressed as soon as possible because of the risk of overboost and catalytic converter damage.

Is P0240 a bad boost sensor?

Not necessarily. OBD-Codes.com points to vacuum lines, the vacuum supply and the wastegate control solenoid, while RepairPal lists wiring, the turbo, an exhaust leak, a brake booster pressure sensor and the PCM. Check the cheap things first before buying parts.

What is the difference between P0236 and P0240?

Both mean the computer doesn't trust the boost reading. OBD-Codes.com uses the same definition for both: measured boost higher than commanded boost. P0236 covers boost sensor A and P0240 covers boost sensor B.

Why do sources call P0240 different names?

OBD-Codes.com calls it Boost Sensor B Range/Performance, while RepairPal's page calls it Boost Sensor B Circuit, the same title it uses for P0239. Your scan tool or service manual will show the exact wording for your vehicle.

How much does it cost to fix P0240?

Neither source gives a repair cost. A cracked vacuum line or a solenoid is usually far cheaper than a turbo, so get a diagnosis or written estimate before buying parts.

Sources

  1. OBD-Codes.com: P0240 Turbocharger Boost Sensor B Range/Performance (Daniel Young, ASE Certified Master Technician)
  2. RepairPal: P0240 Turbocharger/Supercharger Boost Sensor "B" Circuit (rated Urgent)

Last reviewed 2026-10-26. Code definitions and repair steps can vary by manufacturer. Confirm with your vehicle's service information.