Technical Description of OBD-II Trouble Code
The performance of the Turbocharger Wastegate Solenoid B is outside the expected range
What does that mean?
This generic powertrain/engine diagnostic trouble code is typically applicable to turbocharged and supercharged engines, including certain Ford, Mercedes, and Subaru vehicles.
The Powertrain Control Module (PCM) regulates the boost pressure in gasoline or diesel engines by controlling the output circuit to the “B” wastegate/boost pressure control solenoid.
Whenever there is an issue with the overall boost range or engine performance that cannot be attributed to other circuit failures, the PCM will set code P0248. This code can indicate an electrical circuit fault or an engine mechanical problem, depending on the specific fault.
The troubleshooting steps may vary depending on the manufacturer, type of wastegate/boost pressure control, and wire colors to the control solenoid.
Symptoms
The symptoms of a P0248 engine code may include:
Causes
The potential causes for this code to be set are:
Diagnostic and Repair Procedures
A good starting point is always to check for technical service bulletins (TSB) for your particular vehicle. Your issue may be a known problem with a known solution provided by the manufacturer, which can save you time and money during diagnosis.
Next, locate the “B” wastegate/boost pressure control solenoid on your specific vehicle. Once located, visually inspect the connectors and wiring. Look for any scraping, rubbing, bare wires, burn spots, or melted plastic. Disconnect the connectors and carefully examine the terminals (the metal parts) inside the connectors. Check if they appear burned or have a green tint indicating corrosion. If necessary, clean the terminals using electrical contact cleaner and a plastic bristle brush. Allow them to dry and apply electrical grease where the terminals make contact.
The most common failure is due to electrical/vacuum connection issues.
If you have a scan tool, clear the diagnostic trouble codes from memory and see if P0248 returns. If it does not, then the connections were most likely the problem.
If the code does return, you will need to test the solenoid and its associated circuits. Typically, there are 2 wires at the wastegate/boost pressure control solenoid. First, disconnect the harness connected to the wastegate/boost pressure control solenoid. Using a Digital Volt Ohm Meter (DVOM), connect one lead of the meter to one terminal of the solenoid and connect the remaining meter lead to the other solenoid terminal. The circuit should not be open or shorted. Verify the resistance specifications for your specific vehicle. If the solenoid is either open or shorted (infinite resistance or no resistance/0 ohms), replace the solenoid.
If that test passes, use a DVOM to check if there is 12V on the wastegate/boost pressure control solenoid power supply circuit (Red lead to the solenoid power supply circuit, black lead to a good ground). Ensure that the ignition is on. If there is no 12 volts to the solenoid, or if there is 12 volts when the ignition is turned off, repair the wiring from the PCM or relay to the solenoid, or possibly replace the PCM.
If that’s OK, check if there is a good ground at the wastegate/boost pressure control solenoid. Connect a test light to 12V battery positive (red terminal) and touch the other end of the test light to the ground circuit going to the wastegate/boost pressure control solenoid circuit ground. Use the scan tool to actuate the wastegate/boost pressure control solenoid and see if the test light comes on each time the scan tool activates the solenoid. If the test light does not illuminate, it indicates a problem with the circuit. If it does illuminate, wiggle the wiring harness going to the solenoid to see if the test light flickers, indicating an intermittent connection.
Ensure that all mechanical devices are properly attached and functioning. If vacuum-operated, check if there is sufficient vacuum present at the wastegate/boost pressure control solenoid. If not, locate the source of blockage or leakage in the vacuum system.
If all tests have passed so far and you continue to receive a P0248 code, it most likely indicates a failed wastegate/boost pressure control solenoid, although a failed PCM cannot be ruled out until the solenoid has been replaced. If you are unsure, seek assistance from a trained automotive diagnostician. PCMs must be programmed or calibrated to the vehicle in order to be installed correctly.
