P0443
- Powertrain
- Generic (SAE)
- Emissions
Diagnose soon
Emissions related. The engine normally runs fine because purge is not needed for combustion. It becomes more than an emissions issue only if the solenoid is also stuck open mechanically, which adds unmetered vapor at idle and can cause rough running or stalling.
- Safe to drive
- Safe to drive. If it also idles rough, stalls, or is hard to restart after fueling, get it looked at sooner.
Evaporative Emission System Purge Control Valve Circuit
The computer found an electrical problem in the wiring or coil of the purge valve, the solenoid that lets stored fuel vapor into the engine. This is a circuit fault, not a report that the valve is leaking or blocked.
The PCM drives the purge solenoid, usually by switching its ground while a fused ignition feed supplies battery voltage to the coil. The driver monitors the voltage at its own control terminal and compares it to what the commanded state should produce. An open coil, a broken or corroded wire, a short to ground, or a short to voltage produces a mismatch and sets P0443. On many manufacturers P0443 is the general purge circuit code, with P0444 (circuit open) and P0445 (circuit shorted) as the specific sub-codes. P0446 through P0448 are vent control circuit codes and point at the vent valve, not the purge valve.
How the car detected itWith the driver off, the control terminal should sit near battery voltage because the coil pulls it up through the feed. With the driver on, it should be pulled near ground. The PCM samples this feedback, often at key-on before the valve is ever commanded, and again during normal purge operation. Any state that cannot be explained by the command sets the code, typically after a short confirmation period and often on two consecutive drive cycles before the light comes on.
A trouble code records what a control module measured. It does not identify which part failed. Test before replacing anything.
- Safe to drive
- Safe to drive. If it also idles rough, stalls, or is hard to restart after fueling, get it looked at sooner.
- Urgency
- Diagnose soon
- Will it pass emissions
- No
- If ignored
- The EVAP monitor cannot complete, so the vehicle fails inspection and stays not-ready. Vapor builds in the canister without being purged, and once the canister saturates it breaks through to atmosphere, producing fuel odor and a failed emissions test. If the solenoid has failed stuck open, expect idle quality complaints and possible lean fuel trims to follow. Liquid fuel reaching the purge valve and intake comes mainly from repeatedly topping off the tank at the pump, which is worth correcting at the same time.
- Check engine light
- Solid
- Clearing the light
- A completed drive cycle is normally required before the monitor re-runs and the light can clear.
- Possible smell of fuel near tank or engine bay
- Failed emissions inspection
- Loose-cap warning may appear
Many vehicles show no symptom at all beyond the warning light. The absence of a symptom does not mean the fault is not real.
These are the causes this code can have. For the order to work through them in, see what to check first.
| # | Cause | How often | Component |
|---|---|---|---|
| 1 | Purge solenoid electrically failed | Very common | — |
| 2 | Wiring/connector fault | Common | — |
Ordering reflects how often each cause is responsible in general, not a probability for your vehicle. Confirm by testing.
In order. Each of these is cheaper or faster than what follows it, and each one can make the rest unnecessary.
The purge valve connector
Cheapest possible cause. Check for a partly seated connector, green corrosion, spread or backed-out terminals, and oil or coolant intrusion. The valve mounting location varies by manufacturer, so use the service information to find it.
Whether the valve clicks when commanded
A scan tool command with your hand on the valve separates a live circuit from a dead one in under a minute and tells you which half of the circuit to test.
The fuse supplying the solenoid feed
A blown fuse produces an open circuit fault with a perfectly good solenoid, and a repeatedly blown fuse points at a short elsewhere.
Harness routing near heat and movement
The purge valve harness often runs close to the intake, exhaust heat shielding, or a moving engine mount. Chafed insulation is a frequent cause and is visible once you look.
Companion codes
A P0496 high purge flow code alongside P0443 suggests a driver stuck on or a valve stuck open, which changes the direction of the diagnosis.
Record all codes and confirm which sub-code is present
Tools OBD-II scan tool
Note whether the module stored P0443 alone or with a companion such as P0444, P0445, or P0496. The specific code narrows the fault to open, shorted low, or shorted high before you touch a wire. Vent circuit codes in the P0446 to P0448 range point at a different valve entirely.
ExpectedA single circuit code, with freeze frame showing when in the drive cycle it set
Command the purge valve on and off with the scan tool
Tools Bidirectional scan tool
With the key on, cycle the valve while holding it. A clean click each way means the coil and both sides of the circuit are functioning at that moment, which pushes you toward an intermittent fault. No click means a hard fault to find.
ExpectedA distinct click on each command
Check for battery voltage at the solenoid feed terminal
Tools Digital multimeter, wiring diagram
With the key on, either back-probe the feed terminal with the connector still coupled, or unplug the connector and probe the harness-side feed terminal. Identify which terminal is the feed from the wiring diagram; it varies by vehicle. No voltage means work backward through the fuse and relay.
ExpectedBattery voltage on the feed terminal with the key on
Measure the solenoid coil resistance
Tools Digital multimeter, service information
With the connector off, measure across the solenoid terminals. Infinite resistance means an open coil and a failed solenoid. Near zero means a shorted coil. The correct nominal value varies by manufacturer, so compare against the vehicle specification rather than a generic figure.
ExpectedA stable reading matching the vehicle specification, not open and not shorted
Test the control wire back to the module
Tools Digital multimeter, wiring diagram
With the connector unplugged and the module connector unplugged, check the control wire for continuity end to end and for a short to ground or to voltage. A short to ground on the control wire mimics a permanently commanded valve.
ExpectedContinuity end to end and no continuity to ground or to any powered circuit
Perform a wiggle test with the code monitor active
Tools Scan tool, hands
Reconnect everything, put the scan tool in a mode that shows the fault live or watch for a pending code, and flex the harness along its full run while the valve is commanded. Intermittent faults from chafe and corroded terminals show up here and nowhere else.
ExpectedA stable circuit that does not drop out under movement
Repair, then verify with a drive cycle
Tools Scan tool with readiness monitor status
After the repair, clear the code, confirm the valve responds to commands, and run enough of the drive cycle for the EVAP monitor to attempt. Confirm no return of P0443 and check readiness status.
ExpectedNo returning code and an EVAP monitor that runs to completion
| Repair | Only after you confirm | Typical cost | Who |
|---|---|---|---|
| Replace the EVAP purge solenoid | An open or shorted coil measured at the connector, with the feed and control wiring proven good | $110–$320 | DIY |
| Repair or replace the connector, terminals, or pigtail | Visible corrosion, spread or backed-out terminals, or a fault that appears only during a wiggle test | $90–$300 | DIY |
| Repair a chafed, broken, or shorted control or feed wire | An open circuit or a short to ground or voltage measured on that wire with both ends disconnected | $120–$450 | DIY |
| Replace a blown fuse and correct the short that caused it | No voltage at the solenoid feed traced to an open fuse | $40–$300 | DIY |
| Replace or repair the engine control module for a failed output driver | Correct feed voltage, a good solenoid, and clean wiring, with the driver still failing to switch at the module connector | $700–$2,000 | Shop |
US independent shop ranges, parts and labor. Purge solenoid cost swings mainly on accessibility. Some sit on top of the intake and take minutes; others are buried under the manifold or behind the engine. Module replacement includes programming, which is the larger part of that cost.
- Replacing the solenoid without testing the coil or the wiring, when the actual fault is a corroded connector or a chafed control wire.
- Reading P0443 as proof the valve is stuck open. It is an electrical circuit code, and a mechanically leaking valve normally sets a flow code instead.
- Treating P0446, P0447, or P0448 as purge circuit sub-codes. Those are vent control circuit codes and send you to a different valve, usually at the opposite end of the vehicle.
- Skipping the feed side and only testing the control side, which misses blown fuses and open supply wires.
- Condemning the PCM driver early. It does fail, but it is far less common than harness and connector faults and is expensive to get wrong.
- Clearing the code without confirming the EVAP monitor can now complete, then failing an emissions test with readiness not set.
- EVAP Purge Valve
- Purge Valve Wiring
- Definition
- Generic code set (SAE J2012 / ISO 15031-6) via the OBDexopen database, dedicated to the public domain under CC0-1.0.
- Diagnostic guidance
- Written and reviewed in-house. See our editorial policy.
- Review status
- Reviewed
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