If your OBD-II scanner displays P0048, your vehicle’s Engine Control Module (ECM) or Powertrain Control Module (PCM) has detected a high-voltage condition in the Turbocharger/Supercharger Boost Control “A” circuit.

The generic SAE definition for P0048 is:

Turbocharger/Supercharger Boost Control “A” Circuit High

This code applies to turbocharged and supercharged engines equipped with an electronically controlled boost regulation system. Depending on the manufacturer, Boost Control “A” may refer to the:

Turbocharger wastegate control solenoid
Electronic wastegate actuator
Variable Geometry Turbocharger (VGT/VNT) actuator
Boost pressure control solenoid
Supercharger bypass actuator
Electronic boost control motor

Unlike P0047, which indicates a low-voltage condition, P0048 means the ECM is detecting higher-than-expected voltage or lower-than-expected current in the primary boost control circuit.

This commonly indicates:

An open circuit
Excessive circuit resistance
Failed boost control solenoid
Open actuator motor winding
Corroded connector
Broken wiring
Blown fuse
Failed relay
ECM driver fault

Because the boost control system directly regulates turbocharger pressure, P0048 can result in reduced engine performance, limp mode, poor acceleration, and additional turbocharger-related diagnostic trouble codes.

For additional diagnostic information, visit:

Complete OBD-II Code Library: https://my.prostreetonline.com/dtc-obdii/
Body B-Code Library: https://my.prostreetonline.com/dtc-doctor/b-code-obd-ii-codes/
Chassis C-Code Library: https://my.prostreetonline.com/dtc-doctor/c-code-obd-ii-codes/

P0048 Quick Facts

Item	Information
OBD-II Code	P0048
Description	Turbocharger/Supercharger Boost Control “A” Circuit High
Category	Powertrain
System	Forced Induction
Circuit	Boost Control “A”
Severity	Moderate to High
Safe to Drive?	Sometimes
Typical Repair Cost	$100–2,000+

What Does P0048 Mean?

P0048 indicates the ECM has detected a higher-than-expected voltage condition in the Boost Control “A” electrical circuit.

In many electronic control systems, a Circuit High code usually indicates that little or no electrical current is flowing through the circuit.

Rather than excessive battery voltage, the ECM often sees:

An open control circuit
Excessive resistance
A disconnected actuator
A failed solenoid coil
Broken wiring
Missing power supply
Failed relay
Corroded terminals

The ECM expects a specific voltage drop and current draw whenever it commands the boost control actuator. If that electrical response never occurs, P0048 is stored.

What Is Boost Control “A”?

Boost Control “A” refers to the primary electronically controlled component responsible for regulating turbocharger or supercharger boost pressure.

Depending on the vehicle, this may include:

Wastegate control solenoid
Electronic wastegate actuator
Turbo vane actuator
Variable nozzle turbo motor
Supercharger bypass actuator

The “A” designation does not identify a specific side of the engine or turbocharger.

Always consult manufacturer service information before replacing components.

How Turbocharger Boost Control Works

Modern turbocharged engines continuously adjust boost pressure based on:

Accelerator position
Engine speed
Engine load
Intake air temperature
Manifold pressure
Barometric pressure
Knock sensor activity
Exhaust temperature

The ECM calculates a desired boost target and commands the boost control actuator accordingly.

Depending on the design, boost is regulated by:

Vacuum-operated wastegate
Electronic wastegate actuator
Variable geometry turbo vanes
Supercharger bypass valve

Proper operation ensures:

Maximum power
Reduced turbo lag
Safe boost pressure
Lower emissions
Improved fuel economy

How the Boost Control Circuit Operates

The Boost Control “A” circuit typically consists of:

Battery or ignition voltage
Fuse
Relay
ECM driver
Solenoid or actuator
Ground circuit
Position sensor
Feedback circuit

Many boost control systems use pulse-width modulation (PWM).

Rather than supplying constant voltage, the ECM rapidly switches the circuit on and off to regulate actuator movement with great precision.

The ECM also monitors:

Current draw
Voltage
Actuator position
Boost pressure
Response time

If expected electrical feedback is missing, P0048 may be stored.

What Does “Circuit High” Mean?

“Circuit High” generally indicates the ECM is seeing more voltage than expected because current flow is too low or absent.

Typical causes include:

Open wire
Disconnected connector
Failed solenoid coil
Burned-out actuator motor
High resistance
Corroded terminals
Broken fuse
Failed relay

Unlike P0047, this code usually does not indicate a short to ground.

How the ECM Detects P0048

The ECM may set P0048 if it detects:

No current through the actuator
Open boost control circuit
Excessive circuit resistance
Voltage remaining near battery voltage
Missing actuator response
Failed actuator position feedback
Incorrect boost response

The code may occur:

During startup
Under acceleration
During self-tests
During turbo actuator calibration
While towing
During high-load driving

Some vehicles require multiple failed drive cycles before illuminating the Check Engine Light.

P0045 vs P0046 vs P0047 vs P0048

Code	Description
P0045	Boost Control “A” Circuit/Open
P0046	Boost Control “A” Circuit Range/Performance
P0047	Boost Control “A” Circuit Low
P0048	Boost Control “A” Circuit High

Generally:

P0045 = Open circuit detected
P0046 = Mechanical or performance issue
P0047 = Low voltage / excessive current
P0048 = High voltage / insufficient current

Symptoms of P0048

Common symptoms include:

Check Engine Light
Reduced engine power
Limp mode
Slow acceleration
Poor throttle response
Little or no turbo boost
Increased fuel consumption
Turbo lag
Black smoke (diesel)
Underboost condition
Cruise control disabled
Additional boost-related codes

Unlike a sticking wastegate, many P0048 failures prevent the actuator from moving at all.

Common Causes of P0048

1. Open Boost Control Solenoid

An internally open solenoid coil prevents current flow.

This is one of the most common causes.

2. Failed Electronic Wastegate Actuator

Electronic actuators contain:

Electric motor
Position sensor
Internal electronics

An open motor winding or failed electronics can trigger P0048.

3. Broken Wiring

Common damage occurs near:

Turbocharger
Exhaust manifold
Heat shields
Firewall
Engine harness

Heat and vibration eventually fatigue wiring.

4. Corroded Connector

Corrosion increases resistance.

Inspect for:

Green corrosion
White oxidation
Loose terminals
Water intrusion
Bent pins

5. Blown Fuse

A blown boost control fuse removes power from the actuator.

However, determine why the fuse failed before replacing it.

6. Failed Relay

Some vehicles supply actuator voltage through a relay.

A failed relay can leave the actuator without power.

7. Poor Previous Repairs

Common problems include:

Incorrect butt connectors
Twisted wires
Loose terminals
Incorrect pin repairs
Low-quality aftermarket connectors

8. Incorrect Replacement Actuator

Aftermarket components with incorrect resistance values can trigger circuit-high faults.

OEM-quality components are strongly recommended.

9. Failed ECM Driver

Although uncommon, the ECM driver transistor may fail and stop supplying proper control signals.

This should only be considered after verifying all external components.

Is P0048 Serious?

P0048 should be considered moderately serious.

Although immediate engine damage is uncommon, boost control problems can cause:

Reduced power
Limp mode
Poor fuel economy
Incomplete turbo operation
Increased emissions
Excessive exhaust temperatures

Some vehicles may severely reduce engine output to protect the turbocharger.

Can You Drive With P0048?

Usually yes—for a short period.

However, repairs should not be delayed if:

The vehicle enters limp mode
Turbo boost disappears
Heavy smoke develops
Additional turbocharger codes appear
Turbo noises develop
The Check Engine Light flashes

Driving long distances with reduced boost can increase exhaust temperatures and reduce overall engine efficiency.

How to Diagnose P0048

Step 1: Scan for Additional Codes

Look for related faults including:

P0045
P0046
P0047
P0234
P0299
P2261
P2262
P2563

Freeze-frame data often helps identify the operating conditions when the code was set.

Step 2: Inspect Wiring

Look for:

Broken wires
Melted insulation
Chafing
Connector damage
Heat damage
Rodent damage

Step 3: Check the Connector

Disconnect the actuator.

Inspect:

Bent terminals
Corrosion
Loose pins
Moisture
Burn marks

Step 4: Check the Fuse

Verify:

Correct fuse rating
Voltage on both sides
No intermittent connection

Step 5: Measure Component Resistance

Disconnect the actuator or solenoid.

Possible results:

Infinite resistance → Open circuit
Excessive resistance → Internal failure
Normal resistance → Continue testing

Always compare readings with manufacturer specifications.

Step 6: Verify Power Supply

Check for:

Battery voltage
Ignition voltage
Relay output
ECM command voltage

Missing supply voltage often indicates a blown fuse or failed relay.

Step 7: Check Ground Integrity

A poor ground may prevent proper current flow.

Perform voltage-drop testing rather than relying only on continuity.

Step 8: Command the Actuator

Using a bidirectional scan tool:

Command actuator movement
Monitor current
Observe position feedback
Compare commanded vs actual boost

No movement usually indicates:

Failed actuator
Open circuit
Failed power supply

Step 9: Inspect Mechanical Components

Verify:

Wastegate movement
Variable turbo vane movement
Actuator linkage
Turbocharger condition

Although P0048 is electrical, mechanical binding may create secondary faults.

Step 10: Perform Required Calibration

Many electronic wastegate actuators require:

Initialization
End-stop calibration
Position relearn
Adaptation

Failure to perform these procedures may cause the code to return.

Step 11: Verify Repairs

After repairs:

Clear all codes.
Perform any required relearn.
Road-test the vehicle.
Monitor boost pressure.
Verify commanded and actual actuator positions match.
Confirm P0048 does not return.

Common Repairs and Costs

Repair	Estimated Cost
Fuse replacement	$10–50
Wiring repair	$100–500
Connector replacement	$75–250
Boost control solenoid	$120–400
Wastegate actuator	$300–1,200
Relay replacement	$50–200
Actuator calibration	$100–300
Turbocharger replacement	$1,200–4,500+
ECM software update	$100–300
ECM replacement	$1,000–2,500+

Some manufacturers sell the actuator separately.

Others require purchasing the entire turbocharger because apparently replacing a $30 motor would have been far too customer-friendly.

Common Diagnostic Mistakes

Avoid these mistakes:

Replacing the turbocharger before testing wiring
Ignoring blown fuses
Replacing the actuator without checking power
Using continuity testing alone
Skipping actuator relearn
Ignoring connector corrosion
Installing incorrect aftermarket parts
Replacing the ECM first
Confusing P0048 with P0047

Vehicles Commonly Affected

P0048 commonly appears on turbocharged or supercharged vehicles from:

Audi
BMW
Chevrolet
Dodge
Ford
GMC
Honda
Hyundai
Infiniti
Jeep
Kia
Land Rover
Lexus
Mercedes-Benz
MINI
Mitsubishi
Nissan
Porsche
Ram
Subaru
Toyota
Volkswagen
Volvo

Diesel engines with electronic VGT systems are especially susceptible.

How to Prevent P0048

Reduce the likelihood of P0048 by:

Keeping wiring away from exhaust heat
Repairing oil leaks
Using OEM-quality actuators
Replacing damaged connectors
Performing required actuator calibrations
Inspecting harnesses during turbo service
Addressing boost codes early
Replacing brittle vacuum hoses
Keeping electrical connectors dry

Frequently Asked Questions

What does P0048 mean?

P0048 indicates the ECM has detected a high-voltage condition in the Boost Control “A” circuit.

Does P0048 mean high boost?

No.

“Circuit High” refers to electrical voltage—not turbo boost pressure.

What causes P0048?

Common causes include an open actuator, failed boost control solenoid, broken wiring, excessive resistance, blown fuse, failed relay, or ECM driver fault.

Can a bad turbocharger cause P0048?

Usually not directly.

However, a failed electronic wastegate actuator mounted on the turbocharger can trigger the code.

Can I drive with P0048?

Short distances are usually possible, but reduced power and limp mode are common.

Is P0048 the same as P0047?

No.

P0047 indicates low circuit voltage.

P0048 indicates high circuit voltage.

Will replacing the boost control solenoid fix P0048?

It may if the solenoid has an open coil.

Always verify the wiring and power supply first.

Can a blown fuse cause P0048?

Yes.

Loss of actuator power may trigger the code.

Does P0048 require turbocharger replacement?

Not usually.

Most repairs involve the actuator, wiring, connector, fuse, or boost control solenoid rather than the turbocharger itself.

Final Thoughts

The P0048 code indicates a high-voltage condition in the Turbocharger/Supercharger Boost Control “A” circuit. In most cases, this means the ECM cannot see the expected electrical current flowing through the boost control actuator or solenoid because of an open circuit, excessive resistance, or a failed component.

Begin diagnosis by checking the wiring, connectors, fuse, relay, and actuator resistance before replacing expensive parts. Many P0048 repairs involve relatively inexpensive electrical components rather than the turbocharger itself. If your vehicle uses an electronic wastegate actuator, remember to perform any required calibration or relearn procedure after replacement to prevent the code from returning.

Continue diagnosing turbocharger and boost-control faults with these Pro Street guides:

Boost Control Circuit Codes

P0045 Code Explained: Turbocharger/Supercharger Boost Control “A” Circuit/Open
P0046 Code Explained: Turbocharger/Supercharger Boost Control “A” Circuit Range/Performance
P0047 Code Explained: Turbocharger/Supercharger Boost Control “A” Circuit Low

Related Turbo Bypass Valve Codes

P0033 Code Explained: Turbocharger Bypass Valve Control Circuit
P0034 Code Explained: Turbocharger Bypass Valve Control Circuit Low
P0035 Code Explained: Turbocharger Bypass Valve Control Circuit High
P0039 Code Explained: Turbocharger Bypass Valve Control Circuit Range/Performance

Browse the complete Pro Street diagnostic libraries:

Complete OBD-II Code Guide: https://my.prostreetonline.com/dtc-obdii/
B-Code OBD-II Library: https://my.prostreetonline.com/dtc-doctor/b-code-obd-ii-codes/
C-Code OBD-II Library: https://my.prostreetonline.com/dtc-doctor/c-code-obd-ii-codes/

P0048 Code Explained: Turbocharger/Supercharger Boost Control “A” Circuit High Causes, Symptoms & Fixes