20-12-2024
13 min.
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P0248 Turbocharger / Supercharger Wastegate Solenoid "B" Circuit Range / Performance

P0248 is an OBD-II diagnostic trouble code indicating that the engine control module (ECM) has detected a range or performance problem in the control circuit of Turbocharger/Supercharger Wastegate Solenoid �B.�

The wastegate control system is responsible for regulating turbocharger boost. The ECM controls the wastegate actuator through a solenoid or electronic actuator so that the turbocharger produces the desired amount of boost under different engine operating conditions.

The important part of P0248 is “Range / Performance.”

Unlike a simple circuit-high or circuit-low code, P0248 does not necessarily mean that the electrical voltage is simply too high or too low. Instead, the ECM has determined that the wastegate control system is not responding within the expected operating range or is not producing the expected result.

Therefore, P0248 does not automatically mean the turbocharger is defective.

What Does P0248 Mean?

The ECM continuously monitors turbocharger control.

It calculates how much boost the engine should produce and commands the wastegate system accordingly.

Depending on the vehicle, the ECM may monitor:

Wastegate solenoid operation
Solenoid duty cycle
Actuator position
Boost pressure
MAP sensor data
Vacuum or pressure supplied to the actuator
Commanded versus actual boost

If the ECM commands Wastegate Solenoid “B” to operate but the system does not respond as expected, P0248 may be stored.

The problem can therefore be:

Electrical
Pneumatic
Mechanical
Sensor-related
Turbocharger-related
Control-system related

This is why P0248 requires more investigation than simply checking whether the solenoid has power.

What Is Wastegate Solenoid “B”?

A wastegate solenoid regulates the operation of the turbocharger wastegate.

On a conventional system, the ECM may control a solenoid that regulates vacuum or boost pressure going to a wastegate actuator.

The actuator then physically moves the wastegate.

A simplified system may contain:

ECM
Wastegate Solenoid “B”
Vacuum source
Vacuum hoses
Wastegate actuator
Wastegate linkage
Turbocharger
MAP/boost pressure sensor

However, modern turbocharged engines can use electronically controlled wastegate actuators rather than a conventional vacuum diaphragm.

The exact meaning of “B” is manufacturer-specific.

On one engine it may identify a second wastegate control valve. On another, it may refer to a specific turbocharger or control circuit.

You should therefore never assume that Wastegate Solenoid “B” is physically the same component on every vehicle.

What Is a Wastegate?

The wastegate controls how much exhaust energy reaches the turbocharger turbine.

When the wastegate is closed, more exhaust gas flows through the turbine. This allows the turbocharger to accelerate and produce more boost.

When the wastegate opens, some exhaust gas bypasses the turbine.

This limits turbocharger speed and helps prevent excessive boost.

The ECM constantly adjusts this process according to:

Engine load
Engine speed
Throttle position
Requested torque
Intake pressure
Airflow
Temperature
Operating conditions

A wastegate-control problem can therefore have a significant effect on engine performance.

What Does “Range / Performance” Mean?

This is one of the most important parts of the P0248 definition.

“Range/performance” generally means that the ECM sees a control response that is outside the expected operating behavior.

For example, the ECM may command the wastegate system to change position, but the resulting boost or actuator response may not match what the ECM expects.

Possible situations include:

Solenoid responds too slowly
Solenoid does not respond sufficiently
Actuator does not reach the required position
Wastegate is mechanically sticking
Vacuum level is incorrect
Boost pressure does not follow the requested value
Solenoid duty cycle reaches an abnormal limit
Actuator position does not agree with the command

Therefore, P0248 is not simply an “electrical high” or “electrical low” code.

Common Causes of P0248

There are several possible causes.

Faulty wastegate solenoid

The solenoid may have internal mechanical or electrical problems.

It can become slow, sticky, or unable to regulate vacuum/pressure correctly.

Wastegate actuator problem

The actuator diaphragm, electronic motor, position sensor, or internal mechanism can fail.

Sticking wastegate

Carbon deposits, corrosion, heat damage, or mechanical wear can prevent the wastegate from moving freely.

Damaged wastegate linkage

The linkage connecting the actuator to the wastegate can become bent, loose, seized, or disconnected.

Vacuum leak

On vacuum-controlled systems, cracked or disconnected hoses can prevent the actuator from receiving the required vacuum.

Blocked vacuum line

A restricted hose or control passage can also prevent proper actuator operation.

Damaged wiring

The solenoid control circuit may have:

Broken wires
High resistance
Chafed insulation
Corrosion
Intermittent connections

Connector problems

Loose terminals, corrosion, water intrusion, or damaged connectors can cause an inconsistent control signal.

Boost pressure sensor problem

An incorrect MAP/boost-pressure signal can cause the ECM to incorrectly determine how the turbocharger is responding.

Turbocharger mechanical problem

Turbocharger bearing problems, compressor damage, turbine damage, excessive shaft movement, or internal mechanical restrictions can affect boost control.

Exhaust restriction

A restricted exhaust system can alter the amount of energy available to the turbocharger.

Intake or charge-air leak

A leaking intercooler, hose, pipe, or connection can prevent actual boost from reaching the expected level.

ECM control problem

An ECM driver or control problem is possible, but it should generally be considered only after the external components and circuits have been tested.

Symptoms of P0248

Depending on the vehicle, P0248 may produce:

Check Engine Light
Reduced engine power
Poor acceleration
Turbo lag
Inconsistent boost
Surging
Hesitation
Limp mode
Poor fuel economy
Excessive boost
Insufficient boost
Unstable engine performance

Some vehicles may store the code without producing a dramatic drivability problem.

Others may immediately limit turbocharger operation as a protective measure.

Can P0248 Cause Low Boost?

Yes.

If the wastegate remains too open, too much exhaust gas bypasses the turbine.

This can prevent the turbocharger from producing the requested boost.

A faulty solenoid, leaking vacuum hose, defective actuator, or sticking wastegate can all contribute to this situation.

However, low boost does not automatically prove that the wastegate is responsible.

Other possibilities include:

Charge-air leak
Intercooler leak
MAP sensor problem
MAF problem
Exhaust restriction
Turbocharger mechanical damage
Intake restriction

The actual cause needs to be established through testing.

Can P0248 Cause Excessive Boost?

It can.

If the wastegate cannot open when required, the turbocharger may continue receiving excessive exhaust energy.

This can result in boost pressure exceeding the requested value.

Possible causes include:

Stuck-closed wastegate
Faulty actuator
Incorrect solenoid operation
Blocked vacuum/pressure control
Damaged linkage
Incorrect actuator adjustment

However, excessive boost itself does not automatically mean P0248 will be stored.

A mechanical wastegate problem may cause an overboost condition without an electrical fault in the solenoid circuit.

P0248 Does Not Automatically Mean Turbocharger Failure

This is an important diagnostic distinction.

The turbocharger may be mechanically healthy while the wastegate control system is defective.

For example, a cracked vacuum hose can prevent the actuator from moving correctly.

The turbocharger itself may be perfectly functional.

Likewise, a sticking wastegate linkage can create a boost-control problem without any internal turbocharger damage.

Replacing the entire turbocharger before checking the wastegate system can therefore result in an unnecessary and expensive repair.

How to Diagnose P0248

A systematic approach is much more reliable than immediately replacing the wastegate solenoid.

1. Scan All Diagnostic Trouble Codes

Start by scanning the engine and, where appropriate, other vehicle modules.

Record all stored and pending DTCs.

Pay particular attention to codes involving:

Boost pressure
MAP sensor
MAF sensor
Turbocharger control
Wastegate position
Engine voltage
Communication

Additional codes can change the diagnostic direction.

2. Check Freeze-Frame Data

Record the conditions under which P0248 was stored.

Useful information includes:

Engine RPM
Engine load
Vehicle speed
Engine temperature
Throttle position
MAP pressure
Boost pressure
MAF airflow
Battery voltage

If the fault occurs only under high load, that information can be extremely valuable.

3. Identify Wastegate Solenoid “B”

Use the manufacturer's service information to determine exactly which component is designated “B.”

Find:

Solenoid location
Connector pinout
Power supply
Ground/control circuit
ECM control terminal
Expected resistance
Control strategy

Do not rely solely on a generic OBD description.

4. Inspect the Solenoid Connector

Disconnect the solenoid and inspect the connector.

Look for:

Corroded pins
Bent terminals
Loose connections
Water intrusion
Oil contamination
Broken locking tabs
Heat damage

Turbocharger components operate at high temperatures, so connectors and wiring in this area deserve special attention.

5. Inspect the Wiring Harness

Follow the wiring from the solenoid toward the ECM.

Look for:

Chafed wires
Melted insulation
Broken conductors
Poor previous repairs
Harness contact with metal
Heat damage
Loose routing

An intermittent electrical problem may only appear when the engine moves under acceleration.

6. Test the Solenoid Electrically

If manufacturer specifications are available, check:

Coil resistance
Power supply
Ground
Control signal
Current consumption

Do not use a generic resistance value from another vehicle.

Different wastegate solenoids can have significantly different electrical characteristics.

7. Check the Control Signal

Many wastegate solenoids are controlled using PWM.

An oscilloscope can show whether the ECM is actually generating the expected control waveform.

It can reveal:

Missing PWM
Incorrect duty cycle
Intermittent control
Electrical noise
Abnormal switching
Voltage abnormalities

A multimeter can provide basic information, but it may not reveal a brief intermittent problem.

8. Test the Vacuum System

If the system uses vacuum control, inspect every relevant hose.

Look for:

Cracks
Loose connections
Collapsed hoses
Incorrect routing
Blockages
Vacuum leaks

A vacuum pump can be used where appropriate to determine whether the actuator holds and responds to the specified vacuum.

9. Test Wastegate Actuator Movement

The actuator should move smoothly through its specified range.

A technician should verify:

Starting point of movement
Full travel
Smooth movement
Ability to hold vacuum/pressure
Position feedback where applicable

If the actuator is sticking or cannot reach the required position, replacing the solenoid alone may not solve the problem.

10. Inspect the Wastegate Mechanism

The wastegate linkage should move freely.

Check for:

Rust
Carbon deposits
Seized pivot
Bent linkage
Excessive play
Disconnected linkage

A mechanically stuck wastegate can create a range/performance code even when the solenoid and wiring are completely healthy.

Compare Commanded and Actual Boost

This is one of the most important diagnostic tests.

Use live data to compare:

Requested/commanded boost

with

Actual boost

during different operating conditions.

For example, if the ECM requests increased boost but actual pressure remains substantially lower, the technician needs to determine why.

Potential causes include:

Wastegate opening too much
Vacuum leak
Faulty solenoid
Actuator problem
Charge-air leak
Turbocharger problem
MAP sensor error
Exhaust restriction

If actual boost exceeds the requested value, investigate whether the wastegate is failing to open or whether the boost-control system is otherwise unable to reduce turbocharger output.

Check the MAP Sensor

The ECM relies heavily on pressure information to determine whether boost control is working.

A contaminated, damaged, or electrically faulty MAP sensor can report incorrect pressure.

That can cause the ECM to make incorrect boost-control decisions.

Check:

Sensor power supply
Ground
Signal
Live-data reading
Wiring
Connector

Compare the reported pressure with a known reference where appropriate.

Check for Charge-Air Leaks

Inspect:

Turbocharger outlet hose
Intercooler
Intercooler hoses
Intake pipes
Clamps
Connections
Plastic charge pipes
Seals

A boost leak can cause actual boost to remain below the requested value.

A pressure or smoke test can be useful when a leak is difficult to locate visually.

Check the Turbocharger Mechanically

Only after the control system has been evaluated should the turbocharger itself become the primary suspect.

Depending on the turbocharger design, inspect for:

Excessive shaft movement
Damaged compressor blades
Damaged turbine blades
Oil leakage
Foreign-object damage
Housing damage
Unusual mechanical noise

Shaft movement must be evaluated according to the manufacturer's specifications because some movement can be normal depending on the bearing design.

P0248 on Variable Geometry Turbochargers

A variable geometry turbocharger (VGT/VNT) does not use a traditional wastegate in exactly the same way as a conventional fixed-geometry turbocharger.

Instead, adjustable vanes control exhaust flow and turbocharger response.

Some generic diagnostic descriptions may still place related control faults within the turbocharger/wastegate family.

On such systems, diagnosis may involve:

VGT actuator
Vane position
Position sensor
Vacuum control
Electronic actuator
Turbocharger vanes
Boost pressure

Therefore, the generic wording of P0248 should not be taken as proof that the vehicle has a conventional wastegate solenoid.

P0248 on Twin-Turbo Systems

On engines equipped with multiple turbochargers, the letter “B” can become particularly important.

It may identify:

The second turbocharger control circuit
A secondary wastegate actuator
A second solenoid
A specific boost-control valve

The exact definition is manufacturer-specific.

The technician should use the vehicle's wiring diagram and component identification rather than guessing which turbocharger is involved.

Can a Boost Leak Cause P0248?

Yes, it can contribute to a range/performance problem because the ECM may command a particular boost level and see an unexpected actual result.

However, a boost leak does not necessarily mean that the Wastegate Solenoid “B” itself is faulty.

If the vehicle has P0248 together with low boost, both the wastegate system and the charge-air system should be tested.

Can a Vacuum Leak Cause P0248?

Yes, particularly on turbocharger systems that use vacuum-operated actuators.

If the wastegate actuator does not receive the required vacuum, the wastegate may not move as commanded.

The ECM can then detect a performance discrepancy.

Check the entire vacuum circuit rather than only the solenoid.

Common Diagnostic Mistakes

Replacing the turbocharger immediately

P0248 does not directly identify a failed turbocharger.

Replacing the solenoid without checking the actuator

A defective actuator or seized wastegate can produce the same symptoms.

Assuming “B” means the second turbo

The designation is manufacturer-specific.

Ignoring vacuum hoses

A cracked vacuum hose can completely change wastegate operation.

Checking only electrical resistance

Correct resistance does not prove that a solenoid operates correctly under load.

Ignoring boost leaks

A leaking charge-air system can prevent commanded boost from being achieved.

Ignoring the MAP sensor

Incorrect pressure feedback can lead to false conclusions about turbocharger performance.

Ignoring mechanical wastegate movement

A mechanically stuck wastegate cannot be fixed by replacing an electrical component.

Replacing the ECM too early

The ECM should generally be considered only after the external control circuit and mechanical system have been verified.

P0248 vs P0243, P0244, P0245, P0246 and P0250

The surrounding codes help illustrate the difference between circuit faults and performance faults.

P0243 – Wastegate Solenoid “A” Circuit Malfunction

A broad malfunction in the “A” wastegate solenoid circuit.

P0244 – Wastegate Solenoid “A” Range/Performance

The “A” wastegate control system is not behaving within its expected range.

P0245 – Wastegate Solenoid “A” Circuit Low

The ECM detects an abnormally low electrical condition.

P0246 – Wastegate Solenoid “A” Circuit High

The ECM detects an abnormally high electrical condition.

P0248 – Wastegate Solenoid “B” Range/Performance

The “B” wastegate control system is not responding within its expected operating range or performance characteristics.

P0250 – Wastegate Solenoid “B” Circuit High

The ECM detects an abnormally high electrical condition in the “B” control circuit.

This makes P0248 particularly different from P0250: P0248 is primarily a range/performance diagnosis, while P0250 is specifically a circuit-high diagnosis.

A Practical Diagnostic Order

A logical diagnostic sequence for P0248 is:

Scan all modules and record every DTC.
Save freeze-frame data.
Identify the exact Wastegate Solenoid “B.”
Determine the turbocharger control architecture.
Inspect the solenoid connector.
Inspect the wiring harness.
Check power, ground, and control signals.
Test the solenoid according to manufacturer specifications.
Check PWM control where applicable.
Test vacuum or pressure supply.
Test wastegate actuator movement.
Inspect wastegate linkage and mechanical operation.
Check the MAP/boost-pressure sensor.
Inspect the complete charge-air system for leaks.
Compare commanded and actual boost.
Evaluate turbocharger mechanical condition.
Consider ECM control problems only after the rest of the system has been verified.

Final Diagnosis

P0248 – Turbocharger/Supercharger Wastegate Solenoid “B” Circuit Range/Performance means that the ECM has detected that the “B” wastegate control system is not operating or responding within its expected range.

The problem can originate from the wastegate solenoid, wiring, connector, vacuum/pressure system, actuator, wastegate mechanism, MAP sensor, charge-air system, turbocharger, or ECM control circuit.

The most important point is that P0248 does not automatically mean the turbocharger has failed.

Because this is a range/performance code, the diagnosis should evaluate both the electrical control side and the physical response of the boost-control system. Checking commanded versus actual boost, testing actuator movement, inspecting the wastegate mechanism, and verifying the vacuum/pressure system can be just as important as testing the solenoid itself.

A correct repair should therefore be based on actual measurements and system behavior rather than replacing the turbocharger or wastegate solenoid solely because P0248 is stored.