What Does P0238 Mean?
The turbocharger boost pressure sensor A circuit is outputting a voltage above the maximum expected threshold. This typically indicates an open circuit, a short to battery voltage, or a sensor that has failed high. The ECM reads this as impossibly high boost pressure and will enter a protective mode. The driver will likely experience significant power reduction as the ECM limits boost to prevent perceived overboost.
Common Causes
30%
Open circuit in the boost pressure sensor A signal or ground wire
25%
Boost pressure sensor A failed with high output voltage
20%
Short to battery voltage in the sensor signal wire
15%
Disconnected or corroded sensor connector causing open circuit
10%
ECM 5V reference overvoltage or sensor input fault
Diagnostic Steps
1
Check the boost sensor A PID — if it reads maximum boost (e.g., 40+ psi) with the engine off, the circuit is either open or shorted high.
2
Inspect the sensor connector for full engagement, corrosion, or backed-out pins. A disconnected sensor will cause the ECM to see maximum voltage (pulled up to 5V).
3
Unplug the sensor and measure signal wire voltage at the ECM connector — if it reads near battery voltage (12V+), there's a short to B+ in the harness.
4
If unplugging the sensor causes the PID to still read high, the fault is in the wiring. If it changes, the sensor is faulty. Test sensor output with a hand vacuum pump.
5
Verify the sensor ground by measuring continuity from the sensor ground pin to the ECM ground pin — should be under 2 Ω. An open ground causes the signal to float high.
Estimated Repair Cost
$80 - $350
Parts + labor, varies by vehicle and location
The turbocharger boost pressure sensor A circuit is outputting a voltage above the maximum expected threshold. This typically indicates an open circuit, a short to battery voltage, or a sensor that has failed high. The ECM reads this as impossibly high boost pressure and will enter a protective mode...
The most common cause of P0238 (Turbocharger Boost Sensor A Circuit High) is: Open circuit in the boost pressure sensor A signal or ground wire
Typical repair costs for P0238 range from $80 to $350, depending on the vehicle, location, and whether you do it yourself or go to a shop.
The ECM will likely severely limit boost or shut off the turbo system, resulting in significantly reduced power but a safer operating condition. Driving is possible at reduced power but avoid situations requiring full acceleration (merging, passing). Repair promptly to restore normal boost control.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0238 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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