P0243
PowertrainTurbocharger/Supercharger Wastegate Solenoid "A" Malfunction
You'll usually notice this as a sudden flatness when you put your foot down, like the turbo just stopped pulling. The car still drives, but it feels gutless under load and on hills, and the engine light comes on. Behind that, the ECU has found an electrical fault in the wastegate solenoid circuit, the valve that controls how much boost the turbo makes. With that circuit playing up, the ECU can't trust the boost control, so it backs everything off to protect the turbo and engine.
ⓘ Information only. This page provides general educational information about fault code P0243. We do not assess the urgency or safety implications of any specific fault. That requires in-person diagnosis by a qualified mechanic. Full terms.
Recommended next steps
Whether a fault is urgent, drivable, or routine depends entirely on the cause on a specific vehicle, and that can only be determined by a qualified mechanic with diagnostic equipment. If a warning light is illuminated, the most reliable next step is professional diagnosis.
What does P0243 mean?
P0243 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Turbocharger/Supercharger Wastegate Solenoid "A" Malfunction.
This is a standardised OBD-II code. The technical definition is the same regardless of the make or model of vehicle, although specific causes and symptoms can vary between vehicles.
Symptoms commonly associated with this code
Symptoms that drivers often report alongside this code. Not all may apply to every case:
- • Engine warning light on the dash, often the first thing you'll see
- • Clear lack of power pulling away or accelerating, worst under load or climbing a long gradient
- • Boost feels low and throttle response goes sluggish, the engine just doesn't wake up
- • Turbo whine or a clunk that shifts pitch as you get on and off the throttle
- • Limp mode on some cars, capping the revs and throttle so you're stuck crawling home
Possible causes
Causes commonly associated with P0243, listed in approximate order of typical investigation. The actual cause on a specific vehicle can only be confirmed by professional diagnosis.
- 1. Failed wastegate solenoid itself, usually the internal coil burning out or going open circuit. This is the most common cause
- 2. Corroded or loose pins in the solenoid connector, often from water getting into the plug down near the turbo
- 3. Chafed or broken wiring between the solenoid and the ECU, common where the loom rubs on something hot or vibrates against the block
- 4. Short to power or ground somewhere in the solenoid harness
- 5. Split or disconnected vacuum lines to the wastegate actuator, less common but worth a look on older setups
- 6. Rarely, a powertrain control module fault or a calibration issue, only after everything physical checks out clean
How mechanics typically diagnose
A typical diagnostic sequence used by mechanics, provided here for educational reference only. Diagnostic work should be performed by a qualified mechanic with the appropriate tools and training.
- 1. Read the stored code and the freeze frame data, then clear it and see if it comes straight back or only under boost. That tells you whether it's a hard fault or intermittent
- 2. Unplug the solenoid connector and look hard at the pins for green corrosion, moisture, or anything bent. Clean and reseat it, plenty of P0243s are just a dodgy plug
- 3. Wiggle-test the harness between the solenoid and ECU while watching live data, checking for chafing, breaks, or a short to the block
- 4. Measure the solenoid's coil resistance with a multimeter and compare against spec, typically somewhere in the 10 to 30 ohm range. Open circuit or wildly off means the solenoid is done
- 5. Check the vacuum lines and the actuator hose for splits or a connection that's popped off
- 6. If the wiring and solenoid both check out, test for reference voltage at the connector with the ignition on, and see if there's a TSB for your specific model
Common questions about P0243
What's the actual risk if I keep driving like this? +
For short trips it won't strand you, and most cars drop into a reduced-power mode that's safe enough to get home. The problem is that uncontrolled boost regulation puts the turbo at risk. If the wastegate isn't being managed properly you can end up overboosting, and a turbo is a far bigger bill than a solenoid. Drive it gently to a garage rather than hammering it on the motorway with the light on.
How soon do I really need to sort this out? +
Not an emergency, but don't let it sit for weeks. While the fault's live you're losing power and possibly stressing the turbo every time you accelerate hard. Many P0243s turn out to be a cheap fix, a corroded plug or a £40 solenoid, so getting it looked at quickly often saves you money rather than costing it. The longer you leave a boost-control fault, the more chance it does proper damage.
Is it the solenoid itself that's gone, or just the wiring and plug? +
Could be either, and that's exactly why you test before you buy parts. The solenoid coil does burn out, and a resistance reading well outside the 10 to 30 ohm range confirms it. But a fair share of these codes come down to a corroded connector or a chafed wire near the turbo, where heat and vibration take their toll. Check the plug and loom first. No point fitting a new solenoid into a broken circuit.
Information only, not professional advice
The information on this page is provided for general guidance and educational purposes only. It is not a substitute for diagnosis or repair advice from a qualified mechanic. Always verify any fault before paying for repairs. carfaultcodes.co.uk accepts no liability for decisions made based on this information. Full terms →