P0443 means the ECU has detected an electrical fault in the purge control valve circuit — the part of the EVAP system responsible for routing stored fuel vapors into the engine. When this circuit fails electrically, the purge valve may not open or close correctly, causing fuel vapor buildup, emissions issues, or difficulty starting after refueling. In this guide, you’ll learn what P0443 means, the common causes, how to diagnose it, and the repairs that typically solve the problem.
What Does P0443 Mean?
P0443 sets when the ECU commands the purge valve to activate but sees an incorrect electrical response from the circuit. The EVAP purge valve is usually a solenoid that opens and closes based on ECU control. If the valve coil is open, shorted, or receiving the wrong voltage, the ECU detects the fault and triggers P0443.
This code points to an electrical problem rather than a leak. It may involve the purge valve’s internal coil, damaged wiring, corroded connectors, or a failed driver inside the ECU. While drivability may not suffer severely, emissions control and starting performance can be affected.
Quick Reference
- OBD-II Family: P-Code (Powertrain)
- Scope: Generic
- System: EVAP (Evaporative Emission Control)
- Difficulty Level: Intermediate
- Estimated Repair Cost: €40–€200
- Last Updated: 2025-11-24
Real-World Example / Field Notes
On many Ford, Hyundai, and GM vehicles, P0443 appears when the purge valve coil burns out internally. One Ford Focus case involved a purge valve that stuck open for weeks, causing hard starts after refueling. Eventually, the coil failed completely and triggered P0443. Replacing the valve and repairing a corroded connector fixed the issue. Wiring faults near the purge valve connector are extremely common due to heat and vibration.
Symptoms of P0443
- Check Engine Light: The first and most common sign.
- Hard starting after refueling: Purge valve stuck open floods the intake with vapors.
- Rough idle: Especially right after starting.
- Fuel smell: Excess vapor buildup if the valve never opens.
- Poor emissions test results: EVAP monitor will not complete.
- Slight drop in fuel economy: Possible due to incorrect purge flow.
Common Causes of P0443
Most Common Causes
- Failed purge control valve (internal coil open or shorted).
- Corroded purge valve electrical connector.
- Broken or damaged wiring between the valve and ECU.
- Short-to-ground or short-to-power in the purge valve circuit.
- Blown fuse in circuits shared with EVAP components.
Less Common Causes
- Faulty ECU purge valve driver (internal failure).
- Damaged harness near the intake manifold or firewall.
- Water intrusion in the EVAP harness connector.
- Aftermarket wiring modifications causing voltage loss.
- Incorrect replacement purge valve with wrong coil resistance.
Diagnosis: Step-by-Step Guide
Start with basic electrical tests, then confirm purge valve function using scan tool commands.
Tools You’ll Need: OBD-II scanner with active test capability, multimeter, wiring diagram, test light, hand vacuum pump (optional), and basic tools.
- Run an active test with the scan tool. Command the purge valve on/off and listen for clicking. No click = electrical fault.
- Inspect the connector. Look for corrosion, broken pins, or loose locking tabs.
- Check for power and ground. Use a multimeter to verify the purge valve receives proper voltage.
- Measure coil resistance. Typical purge valve coils measure 20–40 ohms. Infinite resistance means an open circuit.
- Check continuity to the ECU. Ensure wiring between the purge valve and ECU has no breaks.
- Test for shorts. Inspect the harness for areas touching metal brackets or heat sources.
- Check relevant fuses. Some vehicles use shared circuits — a blown fuse can set P0443.
- Test purge valve mechanically. Use a hand vacuum pump: it should seal when closed and flow when energized.
- Review freeze-frame data. Note fuel level, temperature, and purge command duty cycle.
- Inspect ECU connector pins. Rarely, spread or corroded ECU pins cause erratic circuit behavior.
Pro Tip: Use a test light in place of the purge valve during active tests. If the test light flashes when the ECU commands purge, the ECU driver is fine — the valve itself is likely faulty.
Possible Fixes & Repair Costs
- Replace purge control valve: The most common repair (€40–€120).
- Repair wiring or connectors: Fixes voltage loss and signal faults (€10–€60).
- Replace blown fuse: Only a temporary fix unless root cause is found (€5–€15).
- Clean and reseat connectors: Often solves intermittent circuit faults (€0–€10).
- Replace ECU (rare): Only if proven faulty after all tests (€200–€400).
Always confirm wiring and coil resistance before replacing the purge valve — many P0443 cases are electrical, not mechanical.
Can I Still Drive With P0443?
Yes, you can drive with P0443 without immediate danger, but the EVAP system will not function correctly. You may experience hard starts after refueling, fuel odors, and failed emissions tests. Long-term driving with continuous vapor buildup is not recommended.
Related Codes
- P0474 – Exhaust Pressure Sensor Intermittent
- P0473 – Exhaust Pressure Sensor High
- P0472 – Exhaust Pressure Sensor Low
- P0471 – Exhaust Pressure Sensor Range/Performance
- P0470 – Exhaust Pressure Sensor
- P0469 – EVAP Purge Flow Sensor Circuit Intermittent
- P0468 – EVAP Purge Flow Sensor Circuit High
- P0467 – EVAP Purge Flow Sensor Circuit Low
- P0466 – EVAP Purge Flow Sensor Circuit Range/Performance
- P0465 – EVAP Purge Flow Sensor Circuit
Key Takeaways
- P0443 indicates an electrical problem in the purge valve circuit, not necessarily a leak.
- Common causes include bad purge valve coils, wiring faults, or corroded connectors.
- Driving is safe short-term but can cause hard starts and emissions issues.
- Always test voltage, coil resistance, and continuity before replacing parts.
FAQ
Is P0443 caused by a bad purge valve?
Often yes. Failed internal coils are one of the most common reasons for P0443, but wiring faults are equally common. Always test both before replacing parts.
Can I drive with P0443?
You can drive short-term, but EVAP performance will be reduced. You may notice fuel smells or hard starts after refueling. Repair it soon to restore emissions compliance.
How is P0443 diagnosed?
A technician uses a scan tool to command the valve on/off, checks for voltage at the connector, measures coil resistance, and inspects wiring and fuses for faults.
Does a loose gas cap cause P0443?
No. Gas cap issues trigger leak codes like P0440 or P0442. P0443 specifically indicates an electrical fault in the purge valve circuit.
Does P0443 affect performance?
Usually no, but it can cause rough starting after refueling or mild idle instability if the purge valve sticks open. Otherwise, drivability is often normal.