# P0443: Evaporative Emission System Purge Control Valve "A" Circuit **Verdict:** Safe to drive Emissions - Generic OBD-II code, applies to all gasoline cars and light trucks sold in the US since 1996. - **Typical cost:** $80-$450 - **Urgency:** Keep driving - **Most likely:** Failed purge valve coil or wiring - **DIY?:** Often, if easy to reach ## Quick answer P0443 means the engine computer has found an electrical problem in the circuit that controls the EVAP purge valve. The purge valve lets stored fuel vapor flow from the charcoal canister into the engine to be burned. The usual causes are a failed valve coil, a broken or corroded wire or connector, or a blown fuse. ## What does P0443 mean? The purge control valve, also called the purge solenoid, sits in the line between the EVAP charcoal canister and the intake manifold. When the engine is warm and running, the engine computer pulses it open so engine vacuum draws stored gasoline vapor into the cylinders to be burned. On most cars the valve gets battery voltage through a fuse when the key is on, and the computer completes the circuit to ground to open it. P0443 is a circuit code, not a flow code. The computer watches the voltage on its control wire while it switches the valve on and off. If that voltage stays where it should not, because a wire is broken or shorted or the coil inside the valve has failed, it sets the code, often on the first trip. "A" names the first or only purge valve, since some turbocharged engines have more than one. With the valve out of control, other EVAP tests may stop running until it is fixed. ## What are the symptoms of P0443? - Check engine light on, usually with no change in how the car runs - Fuel smell near the car on some vehicles if vapor cannot be purged - Rough idle or hard starting after refueling if the valve is also stuck open - EVAP monitor not ready, or a failed emissions test - Other EVAP codes, such as P0441 or P0496, stored alongside it ## What causes P0443? Ranked from most to least likely. Check them in this order: the cheap, common causes first. 1. **Failed purge valve coil** (most common). The solenoid inside the purge valve is a fine coil of wire that heats and cools every time the engine runs. Over years it can open internally or short, so the computer sees the wrong voltage on the control wire. A resistance check across the valve's two terminals, compared with the maker's specification, quickly shows a failed coil. 2. **Damaged wiring or corroded connector** (common). The purge valve harness often runs near hot engine parts or, on some vehicles, along the frame near the fuel tank. Heat, vibration, and road salt can crack insulation, break wires, or corrode connector pins, and rodents sometimes chew engine wiring. Wiggling the harness while watching live data can reveal an intermittent break. 3. **Blown fuse or lost power feed** (less common). On most cars the purge valve shares a fused power circuit with other parts, such as injectors, coils, or oxygen sensor heaters. A short elsewhere on that circuit can blow the fuse and set P0443 along with several other circuit codes. Check the fuse and test for battery voltage at the valve connector with the key on. 4. **Unplugged or mismatched valve after a repair** (less common). P0443 that appears right after engine work often means the purge valve connector was left loose, plugged in without its lock engaged, or damaged while other parts were removed. A replacement valve that is not listed for the exact engine can also have the wrong coil resistance. Check recent work first in these cases. 5. **Faulty engine computer driver** (rare). The engine computer switches the purge valve through an internal driver circuit. A shorted valve coil or a wire shorted to power can overload and damage that driver, so the code returns even with a new valve. This is rare, and a shop should rule out the wiring and valve before repairing or replacing the computer. ## How do you diagnose P0443? 1. Read codes and freeze-frame data, and note any other circuit codes that share the same fuse. 2. Locate the purge valve, often on or near the intake manifold, and check its connector for corrosion or looseness. 3. Measure the valve's coil resistance and compare it with the service manual specification. 4. With the key on, check for battery voltage at the connector, then check the control wire back to the computer for opens or shorts. 5. Use a scan tool to command the valve on and off and listen or feel for clicking. ## How do you fix P0443, and what does it cost? | Fix | Typical cost | What it involves | | --- | --- | --- | | Repair wiring or connector | $100-$350 | Includes tracing the break or short. | | Replace purge valve | $120-$400 | Most are bolt-on parts near the engine; tank-mounted valves cost more to reach. | | Replace fuse and repair the short behind it | $80-$300 | Needed when the fuse blows again after replacement. | Full price breakdowns: [evap purge valve replacement cost](/cost/evap-purge-valve-replacement). ## Is it safe to drive with P0443? > **Safe to drive.** Yes, P0443 is safe to drive with in most cases, since it usually does not affect how the engine runs. Fix it soon if you smell fuel, or if the engine stalls or idles rough after refueling, which suggests the valve is also stuck open. ## Will P0443 fail an emissions test? P0443 with the check engine light on fails an OBD-based emissions test in most states. Because the purge valve cannot be controlled, the EVAP monitor may also refuse to run, leaving it not ready even after the light is off. Some states allow one or two incomplete monitors, but plan on a full repair before testing. ## After the repair: clearing P0443 Once the valve or wiring is fixed, clear the code and use a scan tool to command the valve on and confirm it clicks and the circuit reads correctly. Then drive normally for several days, including a cold start, so the EVAP monitor can finish. No returning P0443 and a ready EVAP monitor mean the repair worked. ## How to prevent P0443 - Inspect engine harnesses for melted or chafed insulation whenever the engine is serviced. - Apply dielectric grease to the purge valve connector when you replace or reconnect it. - Use a purge valve listed for your exact engine rather than a look-alike part. - Fix rodent damage quickly and consider deterrents if animals nest in the engine bay. - Avoid topping off the tank, since liquid fuel can damage the canister and purge valve. ## Codes often seen with P0443 - [P0441](/codes/p0441): Evaporative Emission System Incorrect Purge Flow - [P0496](/codes/p0496): Evaporative Emission System High Purge Flow - [P0440](/codes/p0440): Evaporative Emission System - [P0455](/codes/p0455): Evaporative Emission System Leak Detected (large leak) - [P0446](/codes/p0446): Evaporative Emission System Vent Control Circuit ## Frequently asked questions ### Can I drive with a P0443 code? Yes, most cars run normally with P0443, because the code concerns the valve's electrical circuit rather than the engine itself. You will keep the check engine light on and may fail an emissions test. Repair it sooner if you smell fuel or the engine stumbles right after refueling. ### What is the difference between P0443 and P0441? P0443 means the computer found an electrical fault in the purge valve circuit, such as an open or shorted wire. P0441 means the circuit works but the system did not see the expected purge flow. Both can trace back to the purge valve, but P0443 points first to wiring or the coil. ### How much does it cost to fix P0443? Most P0443 repairs cost $80 to $450 at an independent shop. Replacing an engine-mounted purge valve usually runs $120 to $400, and repairing a damaged wire or connector $100 to $350. Diagnosis time is often a large part of the bill, because the shop must find where the circuit failed. ### Can I replace a purge valve myself? Often yes, if the valve sits on top of the engine with one connector and two hoses. Match the part to your exact engine, inspect the connector, and check the hoses for cracks while you are there. Valves mounted near the fuel tank usually need the car raised safely on stands. ### How do I test a purge valve? Unplug it and measure the coil resistance across its two terminals with a multimeter, then compare the reading with the service manual specification. With the key on, one pin on the harness side should show battery voltage on most cars. A scan tool can also command the valve so you can hear it click. ### Will a bad purge valve cause a rough idle? It can if the valve sticks open mechanically, because extra vapor and air enter the intake at idle. A purely electrical failure usually leaves the valve closed, so the engine runs normally. Rough idling or stalling right after refueling is the classic sign of a purge valve stuck open. ### Can a blown fuse cause P0443? Yes, if the fuse that powers the purge valve blows, the valve loses power and the computer sets P0443. Other parts on the same fuse often set codes too. Replacing the fuse alone is not enough if it blows again, since a short somewhere on that circuit must be found and repaired. ### Will P0443 cause a failed emissions test? Yes, P0443 fails an OBD-based emissions test in most states while the light is on. The EVAP monitor also needs a working purge valve to run, so it may stay not ready. Fix the circuit and drive several days so the monitor completes before you go for the test. ### Where is the purge valve located? On most cars the purge valve sits on or near the intake manifold, with a hose leading back toward the charcoal canister and fuel tank. On some vehicles it is mounted near the canister under the car instead. A parts diagram or service manual for your exact engine shows the location. ### Why does P0443 keep coming back after a new purge valve? If P0443 returns after a new valve, the fault is usually in the wiring, connector, or fuse circuit rather than the valve itself. A chafed wire may short only when the engine moves or heats up. Rarely, the engine computer's internal driver has been damaged and needs repair. ## Sources - [SAE J2012: Diagnostic Trouble Code Definitions](https://www.sae.org/standards/content/j2012_201812/) - [EPA: On-Board Diagnostics (OBD)](https://www.epa.gov/state-and-local-transportation/vehicle-emissions-board-diagnostics-obd) ## Other emissions codes - [P0430 Catalyst System Efficiency Below Threshold (Bank 2)](https://diagxcar.com/codes/p0430) - [P0431 Warm Up Catalyst Efficiency Below Threshold (Bank 2)](https://diagxcar.com/codes/p0431) - [P0440 Evaporative Emission System](https://diagxcar.com/codes/p0440) - [P0441 Evaporative Emission System Incorrect Purge Flow](https://diagxcar.com/codes/p0441) - [P0442 Evaporative Emission System Leak Detected (small leak)](https://diagxcar.com/codes/p0442) - [P0446 Evaporative Emission System Vent Control Circuit](https://diagxcar.com/codes/p0446) - [P0449 Evaporative Emission System Vent Valve/Solenoid Circuit](https://diagxcar.com/codes/p0449) - [P0451 Evaporative Emission System Pressure Sensor/Switch "A" Circuit Range/Performance](https://diagxcar.com/codes/p0451) - [P0452 Evaporative Emission System Pressure Sensor/Switch "A" Circuit Low](https://diagxcar.com/codes/p0452) - [P0455 Evaporative Emission System Leak Detected (large leak)](https://diagxcar.com/codes/p0455) ## Symptoms - [Why does my car smell like gas?](https://diagxcar.com/symptoms/car-smells-like-gas) - [Why is my car idling rough?](https://diagxcar.com/symptoms/rough-idle) ## Repair costs - [EVAP purge valve replacement cost](https://diagxcar.com/cost/evap-purge-valve-replacement): $120-$350 --- Source page: https://diagxcar.com/codes/p0443 Updated: 2026-11-03 General information, not a substitute for a qualified mechanic.