P0243

What the Code Means

Code P0243 points to a fault in the wastegate control solenoid circuit on the turbocharger. The solenoid drives the vacuum or electric wastegate actuator and regulates boost pressure. An electrical fault — open circuit, short, or a bad signal — disrupts the system and you lose control of boost.

How the System Works

The wastegate solenoid receives a signal from the DME (Digital Motor Electronics) and modulates vacuum or voltage to open and close the flap. When the solenoid fails, the DME can't regulate boost pressure accurately, which causes a power loss or limp mode.

Symptoms

• Check Engine light (MIL) on, code P0243 stored in the DME
• Low boost — the car won't make full power, especially under acceleration
• Limp mode — the DME limits boost to protect the engine
• Inconsistent power — surging or flat spots when you press the throttle

Symptoms can show up on a cold or warm engine, most often under load.

Diagnosis and Repair

Step 1: Confirm the Code

• Hook up a scan tool (ISTA, INPA, or a multi-brand scanner) and pull the codes. Make sure P0243 is active or stored.

Step 2: Visual Inspection

• Check the wastegate solenoid connector for corrosion, damaged pins, or contamination.
• Inspect the wiring harness for kinks, breaks, or signs of overheating.

Step 3: Electrical Check

• Disconnect the solenoid connector.
• Measure resistance across the solenoid terminals: the normal value is 10–20 ohms. If it's out of range or open, the solenoid is bad.
• Check for 12 V at the power pin with the ignition on.
• Check the ground circuit — resistance to the body should be less than 1 ohm.

Step 4: Replace the Solenoid

• If the electrical values are out of spec, replace the solenoid. Original part number: 11657588856.
• After replacement, reset the DME adaptations and check that the boost system works.

Common Diagnostic Mistakes

• Not checking power and ground before replacing the solenoid.
• Ignoring the vacuum lines (on a vacuum system) — leaks can mimic a bad solenoid.

Downstream Consequences

Ignoring P0243 can lead to the following:

• Stuck wastegate — with a failed solenoid, the flap can stick open or closed. That causes either underboost or overboost.
• Turbocharger damage — prolonged overboost puts excessive load on the turbo bearings and compressor wheel, which can destroy the turbo.
• High exhaust gas temperatures — poor wastegate control can overheat the catalytic converter and oxygen sensors.

Severity: Moderate. Fix the fault as soon as possible to avoid an expensive turbocharger repair.

Typical cost of the consequences: A turbocharger replacement is an expensive repair, and the cost can vary significantly depending on the BMW model and region.