P0243 Code: Turbocharger Wastegate Solenoid A Circuit
The engine computer found a fault in the electrical circuit of the solenoid that controls the turbo wastegate.
Unverified: this manufacturer-specific definition comes from a single source or varies by model. Confirm it with a brand-specific scan tool.
At a glance
Severity: Moderate
- Meaning
- Turbocharger Wastegate Solenoid A Circuit
- System
- Fuel & Air Metering · Powertrain
- Safe to drive?
- Yes, short term
- Typical repair cost
- $0–$1,800
- DIY difficulty
- Moderate
On a wastegate turbo, a small three-port solenoid sits between a pressure source and the wastegate actuator and decides how much signal the actuator gets. The engine computer pulses it many times a second and checks that the circuit behaves like a healthy coil. P0243 means that check failed without the manufacturer specifying high or low, so it covers opens, shorts and intermittent contact. Some manufacturers use P0045 for the same valve, so the wording of the code depends on the car. When the solenoid stops working, a pressure-operated wastegate opens at its spring rating and the engine is held to low base boost, which is safe but noticeably slower. Exact circuit logic varies by model, so check the service information for your engine.
Can I keep driving? Safe to drive in most cases, because the wastegate defaults to opening and boost stays low. Expect weak acceleration, and get it repaired before relying on the car for towing or long highway trips.
How to read P0243
- P Powertrain
- 0 Generic (SAE)
- 2 Fuel & air (injector circuit)
- 43 Specific fault
Symptoms
- Check engine light with noticeably lazy acceleration
- Boost tops out at a low, fixed value on a gauge or scan tool
- Fault often appears after the engine is fully hot and disappears when cold
- No change in the turbo's sound when you press harder
- Sometimes a companion underboost code
Possible causes
Ranked by how often each cause is behind this code (editorial estimate).
- Connector at the wastegate solenoid loose, corroded or with a pushed-back terminal
- Solenoid coil breaking down when heat-soaked (opens up hot, works cold)
- Harness melted or chafed near the turbo, downpipe or heat shield
- Power feed fuse or relay problem shared with other emission solenoids
- Water or cleaner intrusion after an engine wash
- Incorrect replacement solenoid or boost controller wired in its place
- Engine computer output driver fault
Diagnosis step by step
Identify which valve is solenoid A
Use the service information to locate wastegate solenoid A; engines with twin turbos or two-stage control have more than one. It's usually a plastic valve with three ports, mounted on the intake tube, strut tower or the turbo bracket, with hoses to the compressor outlet, the compressor inlet and the wastegate can.
Tools: Flashlight
Measure the coil hot and cold
Measure coil resistance across the solenoid pins with the engine cold, then again right after a hot drive. Most read about 20 to 40 ohms and change only a few ohms with temperature. A coil that reads normal cold but goes open or jumps sharply when hot explains a code that sets only after warm-up.
Tools: Multimeter
Check current draw with an amp clamp
With the solenoid connected, clamp a low-amp probe around one wire and command the solenoid at 100% in the scan tool. A healthy 12-volt, 30-ohm coil pulls roughly 0.4 A. Zero current means an open in the circuit; a much higher value points to a shorted coil.
Tools: Multimeter, OBD-II scanner
Check the pulse signal at the connector
Back-probe the control wire and set the meter to duty cycle or frequency while an assistant raises rpm under the actuator test. You should see the duty cycle change as the command changes. A steady 12 V or a steady 0 V with the command changing narrows it to the wire or the computer.
Tools: Multimeter, OBD-II scanner
Base-boost test to protect the diagnosis
With the solenoid unplugged, a safe, short pull should still make the wastegate's spring boost, often around 5 to 8 psi. If boost is far below that, there's also a mechanical or leak problem to fix, not just the electrical fault.
Tools: OBD-II scanner
Inspect the computer connector if the wiring checks out
Before condemning the engine computer, unplug its connector and look for corrosion, water or a spread pin on the solenoid's control terminal. Check continuity from that pin to the solenoid connector; it should be under 1 ohm.
Tools: Multimeter, Flashlight
Where the parts are
- 1Upstream O2 sensor
- 2Catalytic converter
- 3Downstream O2 sensor
- 4Diesel particulate filter
- 5Turbocharger
Repair options & costs
| Repair | DIY? | Estimated cost |
|---|---|---|
| Clean and secure solenoid connector | Yes | $0–$90 |
| Replace wastegate solenoid | Yes | $80–$320 |
| Repair heat-damaged harness and add heat sleeve | No | $120–$450 |
| Replace fuse or relay feeding the solenoid | Yes | $10–$90 |
| Repair or replace engine computer | No | $600–$1,800 |
Rough US estimates for parts and labor; shop rates vary by region. Not a quote.
Emissions / smog test impact
Will fail
States with OBD-II testing fail a car with the check engine light lit. After fixing the circuit, the code usually clears once the computer sees the solenoid working over a few drive cycles.
Frequently asked questions
How much boost will I have with a dead wastegate solenoid?
On a typical pressure-operated wastegate, only the spring's base boost, often about 5 to 8 psi instead of the 15 to 22 psi a modern small turbo engine makes at full load. The car feels more like a non-turbo engine of the same size.
Could this code lead to overboost?
Usually not. Most wastegate systems are designed so a dead solenoid lets the wastegate open early. Overboost with P0243 would suggest a hose or mechanical problem as well, which is a separate fault worth checking.
Why does the code only appear after a long drive?
The wastegate solenoid often sits close to the turbo, and heat raises the coil's resistance. A coil with a cracked winding or a weak solder joint can lose contact only when it's hot, which is why testing it after a hot drive matters.
Is P0243 the same as P0045?
They can describe the same valve, depending on how the manufacturer named it. P0243 is labeled as a wastegate solenoid, P0045 as a general boost control solenoid, which also covers valves that drive variable-vane turbos.