What Does P0242 Mean?
The turbocharger boost pressure sensor B circuit voltage is higher than the ECM expects. This typically means the sensor signal is stuck near or above 4.5V, which is outside the normal operating range for a 5V reference sensor. The ECM cannot accurately determine boost pressure from sensor B. The driver will likely experience reduced power and possible limp mode.
Common Causes
30%
Short to voltage in the boost sensor B signal wire
30%
Faulty boost pressure sensor B with internal short to reference voltage
20%
Open ground circuit for sensor B causing the signal to float high
15%
Corroded or disconnected connector at sensor B
5%
ECM internal pull-up fault on the sensor B input circuit
Diagnostic Steps
1
Monitor boost sensor B PID — if it reads maximum boost or an implausibly high value at idle (when boost should be near atmospheric), the signal is stuck high.
2
Disconnect the boost sensor B connector and measure signal wire voltage at the harness side — if it drops to near 0V, the sensor is internally shorted to the 5V reference. If voltage remains high, there is a short to voltage in the wiring.
3
Check the sensor ground pin for continuity to the ECM ground — an open ground circuit will cause the signal to float to near 5V. Resistance should be less than 1 ohm.
4
Inspect the sensor connector for corrosion, pushed-back pins, or moisture intrusion that could bridge the signal pin to the 5V reference pin.
5
If wiring and connector check out, replace the boost pressure sensor B and clear the code. Verify the new sensor reads approximately 2.3-2.7V at atmospheric pressure with the engine off.
Estimated Repair Cost
$80 - $400
Parts + labor, varies by vehicle and location
The turbocharger boost pressure sensor B circuit voltage is higher than the ECM expects. This typically means the sensor signal is stuck near or above 4.5V, which is outside the normal operating range for a 5V reference sensor. The ECM cannot accurately determine boost pressure from sensor B. The dr...
The most common cause of P0242 (Turbocharger Boost Sensor B Circuit High) is: Short to voltage in the boost sensor B signal wire
Typical repair costs for P0242 range from $80 to $400, depending on the vehicle, location, and whether you do it yourself or go to a shop.
The ECM will likely enter limp mode with limited boost to protect the engine. Driving is possible at reduced speeds but the engine is running on incomplete data. Avoid heavy loads and high RPM operation. Repair promptly to restore proper boost control.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0242 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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