What Does P0240 Mean?
The turbocharger boost pressure sensor B circuit is reporting values outside the expected range, or the sensor response does not match expected performance characteristics during operation. The ECM sees erratic, sluggish, or out-of-range readings from this sensor. The driver may notice reduced engine power, rough running under boost, or limp mode activation.
Common Causes
35%
Faulty boost pressure sensor B with degraded internal element
25%
Vacuum/pressure reference hose to sensor B cracked, kinked, or blocked
20%
Boost leak in the intake system causing lower-than-expected readings
15%
Corroded or damaged wiring/connector at sensor B
5%
Carbon or oil contamination at the sensor port
Diagnostic Steps
1
Monitor boost sensor B live data PID at idle — it should read approximately atmospheric pressure (98-102 kPa at sea level). If it reads significantly higher or lower, the sensor or its reference line is faulty.
2
Compare boost sensor B reading against the MAP sensor and boost sensor A (if equipped) during a controlled acceleration. All sensors should track closely together. A sluggish or erratic sensor B response indicates a failing sensor.
3
Inspect the pressure reference hose to sensor B — remove it and check for carbon buildup, oil contamination, or kinks. Blow through the hose to confirm it is clear.
4
With the sensor disconnected and key on, check the reference voltage at the sensor connector — it should be approximately 5.0V on the reference pin and a solid ground on the ground pin.
5
Apply known pressures to the sensor using a hand vacuum/pressure pump. The sensor output should change linearly: approximately 0.5V at vacuum, 2.5V at atmospheric, and 4.5V at full boost. Replace if non-linear or erratic.
Estimated Repair Cost
$80 - $350
Parts + labor, varies by vehicle and location
The turbocharger boost pressure sensor B circuit is reporting values outside the expected range, or the sensor response does not match expected performance characteristics during operation. The ECM sees erratic, sluggish, or out-of-range readings from this sensor. The driver may notice reduced engin...
The most common cause of P0240 (Turbocharger Boost Sensor B Circuit Range/Performance) is: Faulty boost pressure sensor B with degraded internal element
Typical repair costs for P0240 range from $80 to $350, depending on the vehicle, location, and whether you do it yourself or go to a shop.
The vehicle may run in limp mode with reduced power. Inaccurate boost readings can cause improper fuel metering and detonation risk. Driving at moderate speeds with light throttle is generally acceptable, but avoid heavy loads, towing, and sustained high-speed driving.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0240 to identify the root cause.
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Quick Info
Category
Powertrain
System
Turbocharger / Supercharger System
Difficulty
Type
Generic (SAE)
Recommended Tools
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