P0443 Code: EVAP Purge Control Valve Circuit
The ECU detected an electrical fault in the purge solenoid circuit: open, shorted or a bad driver.
At a glance
Severity: Low
- Meaning
- EVAP Purge Control Valve Circuit
- System
- Emission Controls · Powertrain
- Safe to drive?
- Yes, short term
- Typical repair cost
- $10–$1,500
- DIY difficulty
- Moderate
The purge solenoid is fed with battery voltage from a fuse or the main relay, and the ECU switches its ground side on and off many times per second to meter vapor into the engine. While doing that, the ECU monitors its own output: with the driver off it expects to see battery voltage coming back through the coil, and with the driver on it expects the line to be pulled low with a sensible current. P0443 means that feedback didn't match: a coil that is open or has shorted turns, a broken or chafed wire, a missing fuse feed, or a damaged driver in the ECU. Older ECUs use P0443 for every kind of purge circuit fault; newer ones split out P0444 (open) and P0445 (shorted), so P0443 on a modern car often points to a short or an overloaded output rather than a simple open. It says nothing about hoses or leaks.
Can I keep driving? You can keep driving. The ECU normally stops purging once it logs the fault, so expect a gasoline smell as the canister overfills; if the idle becomes rough or the engine stalls after refueling, the valve may be stuck open and needs attention soon.
How to read P0443
- P Powertrain
- 0 Generic (SAE)
- 4 Auxiliary emission controls
- 43 Specific fault
Symptoms
- Check engine light with P0443 stored, often after rain or a car wash
- No ticking from the purge valve at warm idle when it normally clicks
- Gasoline smell around the car after a few days of driving (canister not being emptied)
- Rough idle and hard hot starts if the control wire is shorted to ground and holds the valve open
- Other codes on the same fuse circuit, such as injector or coil faults
Possible causes
Ranked by how often each cause is behind this code (editorial estimate).
- Purge solenoid coil failed (open winding or shorted turns)
- Connector corroded, loose or with a spread terminal
- Control wire chafed through against the intake or engine and shorted to ground
- Fuse or relay feeding the solenoid blown or failing
- Wire broken inside the harness near a bend or clip
- ECU output driver damaged, usually after a shorted solenoid
Diagnosis step by step
Note all circuit codes and the fuse layout
Look for P0444, P0445 or codes from other components on the same fuse. Several circuit codes at once point to the shared power feed; P0443 alone points to the solenoid or its two wires.
Tools: OBD-II scanner
Measure coil resistance
Unplug the solenoid and measure across its terminals. Most purge valves read roughly 15-35 ohms; an open reading means a broken winding, and anything below about 10 ohms suggests shorted turns that overload the ECU driver.
Tools: Multimeter
Check power and ground control at the harness
Key on, engine off: one terminal of the harness should show battery voltage. Connect a test light between that terminal and the control terminal and command purge with a scan tool; the light should flicker or glow in step with the duty cycle.
Tools: Multimeter, OBD-II scanner
Look for a short to ground
With the ECU and solenoid unplugged, measure between the control wire and chassis ground. Any continuity means the wire is chafed; follow it along the intake, fuel rail and valve cover where the harness rubs.
Tools: Multimeter, Flashlight
Wiggle-test while monitoring
With the engine idling and purge active, flex the harness and connector while watching the scan tool for the code to reset or the purge duty to drop to zero. Intermittent faults after rain often show up this way.
Tools: OBD-II scanner
Protect the ECU when replacing the valve
If the old solenoid was shorted, confirm the ECU still switches the new one before closing up. A driver that was overheated may work at first and fail again later; some ECUs log a separate driver fault in that case.
Tools: OBD-II scanner, Multimeter
Where the parts are
- 1Gas cap
- 2Charcoal canister
- 3Purge valve
- 4Vent valve
- 5Fuel pump
- 6Intake manifold
Repair options & costs
| Repair | DIY? | Estimated cost |
|---|---|---|
| Replace purge solenoid | Yes | $90–$260 |
| Repair connector or install pigtail | No | $80–$200 |
| Repair chafed control wire | No | $100–$300 |
| Replace fuse or relay | Yes | $10–$60 |
| Repair or replace ECU (rare) | No | $600–$1,500 |
Rough US estimates for parts and labor; shop rates vary by region. Not a quote.
Notes by brand
Volkswagen
On VW, Audi, Skoda and Seat gasoline engines the purge valve (N80) sits in the engine bay close to the intake. Coil failures and corroded connectors on this valve are a common source of purge circuit codes.
Field data
| Ford | 7 | Focus, Focus Bev, Escape | |
|---|---|---|---|
| Chevrolet | 4 | Volt |
Source: NHTSA Complaints API (US government open data), analyzed by DTC mention.
Emissions / smog test impact
Will fail
P0443 turns on the check engine light and is an automatic fail at an OBD-II smog inspection. After the repair the EVAP monitor must run again, so allow a few days of normal driving before the test.
Frequently asked questions
Can I simply unplug the purge valve and drive?
You can drive, but it won't solve anything: the code stays on, the canister overfills and vapor escapes as a fuel smell. The valve is cheap and usually easy to reach, so repairing it is the better route.
What's the difference between P0443 and P0444?
P0444 is specifically an open circuit. P0443 covers any electrical fault on the purge output, and on newer cars that also have P0444 and P0445 it often means a short or an overloaded driver.
Why did the code appear after a car wash?
Water in a corroded connector can bridge or interrupt the circuit for a while. If the code keeps coming back after wet weather, clean and seal the connector or replace the pigtail.
Could the ECU be bad?
Possible but uncommon. Only suspect it once the coil, fuse feed and both wires test good; a shorted solenoid is the usual thing that damages the driver, so fix that first.
Sources
- SAE J2012 – Diagnostic Trouble Code Definitions
- ISO 15031-6 – Road vehicles, diagnostic trouble code definitions (EOBD)
- US EPA – On-Board Diagnostics (OBD) program
- Manufacturer public service information (cross-checked)
- NHTSA Complaints API
- Methodology: How We Build Code Pages · Data Sources We Use · Editorial Policy