OBD-II Code P0243 — What It Means & How to Fix It

What Does This Error Mean?

P0243 means the PCM detected an electrical fault in the turbocharger wastegate solenoid A circuit. The wastegate controls how much exhaust drives the turbo — and therefore how much boost the engine makes. A faulty wastegate solenoid can cause over-boost, under-boost, or erratic power delivery. You may notice power loss, hesitation, or the vehicle going into reduced power mode.

Affected Models

All 1996+ turbocharged vehicles with electronically controlled wastegates
Common in Ford EcoBoost 1.5T, 2.0T, and 2.3T engines
Common in Subaru turbocharged WRX and Forester models
Common in Volkswagen and Audi 1.8T and 2.0T engines
Common in diesel trucks with electronically controlled variable geometry turbos

Common Causes

Failed wastegate bypass regulator solenoid with an open or short circuit internally
Damaged or corroded wiring in the solenoid control circuit
Loose or corroded connector at the wastegate solenoid plug
Clogged wastegate solenoid from oil residue or carbon buildup
Failed PCM driver circuit for the wastegate solenoid output (uncommon)

How to Fix It

Locate the wastegate solenoid on your turbocharged engine. It is typically a small cylindrical valve mounted on or near the turbocharger or intake manifold. It usually has two vacuum hose connections and a two-pin electrical connector.

On some vehicles the solenoid is mounted on a bracket on the firewall or strut tower. Check your service manual or a model-specific forum for the exact location.
Unplug the solenoid electrical connector and measure the solenoid's resistance with a multimeter on the ohms setting. Most wastegate solenoids read between 20-40 ohms. An open circuit or short circuit confirms an internal solenoid failure.

Look up the exact resistance specification for your vehicle. Some solenoids are designed for different resistance ranges depending on the manufacturer.
Inspect the vacuum or boost hoses connected to the solenoid. Look for cracks, splits, collapsed sections, or hoses that have come off their fittings. A disconnected hose will prevent proper wastegate operation and may set this code.

Rubber vacuum hoses become brittle with heat and age. A cracked hose is a common and inexpensive cause of this fault.
Check the wiring harness and connector at the solenoid. Look for corroded pins, broken wires, or loose connections. Spray the connector with electrical contact cleaner, clean the pins, and reconnect firmly.

Solenoid connectors near the turbo are exposed to extreme heat cycles which accelerates connector and wire deterioration.
Replace the wastegate solenoid if resistance testing confirms an internal fault or cleaning does not help. Clear the fault codes and perform a test drive under boost conditions to confirm normal operation and no return of the code.

Wastegate solenoids are often inexpensive. On many popular vehicles, good-quality replacements are available for under $50.

When to Call a Professional

If replacing the solenoid and cleaning connections does not resolve the code, the wiring or PCM needs further testing. A technician can scope the solenoid control signal from the PCM and check circuit resistance. Diagnosis typically costs $80-$130. Wastegate solenoid replacement usually runs $100-$250 depending on the vehicle.

Frequently Asked Questions

What does the wastegate solenoid actually do?

The wastegate is a valve that releases exhaust pressure past the turbo. By opening it, boost pressure is reduced. By keeping it closed, more exhaust spins the turbo and boost increases. The PCM controls the solenoid electronically to maintain the target boost level. A faulty solenoid means the PCM loses control over boost.

Can a bad wastegate solenoid damage my engine?

Yes, it can — especially if the wastegate stays closed. A stuck-closed wastegate allows unrestricted boost pressure to build. Over-boost can cause engine knock, damaged pistons, or blown head gaskets. Get this fixed before driving hard or under heavy load.

Is P0243 expensive to fix?

Usually not, if the solenoid itself is the problem. Solenoids for popular turbocharged engines often cost $30-$80 for the part. Labor to access and replace them is typically 1-2 hours. If the wiring or PCM is at fault, costs increase significantly.