What Does P0048 Mean?
The PCM has detected that the turbocharger/supercharger boost control 'A' circuit is reading a higher voltage or signal than expected. This typically indicates a short to battery voltage in the solenoid control circuit, causing the solenoid to be energized continuously or the PCM to see an abnormally high signal. The driver may experience overboosting, inconsistent boost levels, or the vehicle may enter limp mode.
Common Causes
35%
Short to battery voltage in the boost solenoid wiring (control wire chafed against a power source)
25%
Internally shorted boost control solenoid (coil shorted to power feed)
20%
Corroded or damaged connector with cross-pin contact between power and signal wires
20%
PCM boost control driver failure (output stuck high)
Diagnostic Steps
1
Disconnect the boost control solenoid and measure voltage on the PCM control wire — with KOEO it should be near 0V when the solenoid is not commanded on. Voltage present indicates a short to power in the harness or a PCM driver fault.
2
Measure the solenoid coil resistance (expect 10–30 ohms). Check for continuity between the control terminal and the power supply terminal — there should be none.
3
Trace the boost solenoid wiring harness from the connector back toward the PCM, looking for areas where the control wire may be chafing against wires carrying battery voltage.
4
With the solenoid disconnected and the PCM connector disconnected, verify no voltage is present on the control wire — this isolates whether the short is in the harness, solenoid, or PCM.
5
If the wiring is clean, reconnect the solenoid and use a current clamp to monitor the solenoid current while commanding it on and off via bi-directional controls — verify it responds correctly to commands.
Estimated Repair Cost
$100 - $550
Parts + labor, varies by vehicle and location
The PCM has detected that the turbocharger/supercharger boost control 'A' circuit is reading a higher voltage or signal than expected. This typically indicates a short to battery voltage in the solenoid control circuit, causing the solenoid to be energized continuously or the PCM to see an abnormall...
The most common cause of P0048 (Turbocharger/Supercharger Boost Control "A" Circuit High) is: Short to battery voltage in the boost solenoid wiring (control wire chafed against a power source)
Typical repair costs for P0048 range from $100 to $550, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Use caution — a continuously energized boost solenoid can potentially cause overboosting, which risks engine damage from excessive cylinder pressure and detonation. If you hear unusual turbo sounds or the vehicle feels excessively powerful, stop driving immediately. Limp mode should protect the engine in most cases.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0048 to identify the root cause.
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Quick Info
Category
Powertrain
System
Forced Induction / Turbocharger
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
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