What P0443 means
The evaporative emission (EVAP) system stores fuel vapour from the tank in a charcoal canister; a purge valve lets the engine draw it off, and a vent valve opens the canister to fresh air.
How the engine computer detects it
P0443 is the electrical check of purge valve A, which the module switches to ground in pulses; it compares the driver's feedback voltage with the commanded state. GM uses it for an open circuit (200 kΩ or more, 20 of 25 samples, MIL after two trips) and reports shorts as P0458/P0459; Ford covers open and short in P0443 (5 s). Purging then stops, the canister is no longer regenerated, and the leak and purge monitors are suspended.
Written from public technical sources and not yet checked by a mechanic. How we write these pages
Symptoms
- Check engine light on
- Possibly fuel smell (no purging)
- EVAP leak test does not run
Common causes
- Purge valve connector corroded, loose or off Most likely
- Purge valve coil open or shorted Possible
- Control wire broken or chafed, or supply missing (fuse, main relay) Possible
- Driver in the engine module Less likely
How to diagnose P0443
- Read every stored code with an OBD-II scanner. If misfire or fuel trim codes are there too, fix those first: they often cause this one.
- Inspect the parts involved: evap purge valve, purge valve wiring, engine control module.
- Work through the causes above from most to least likely, cheapest checks first.
- Clear the code and drive a full drive cycle to confirm the repair held.
Vehicles that report P0443 most
| Vehicle | Years | Reports | Share | Median miles |
|---|---|---|---|---|
| Ford Focus | 2012–2016 | 5 | — | |
| Chevrolet Volt | 2016–2018 | 4 | — |
Counts of owner complaints to the NHTSA that mention P0443 (17 in total), not failure rates: popular models get more complaints simply because more of them are on the road. Models with fewer than 3 complaints are left out.
Reading the code
- P
- Powertrain
- 0
- Generic (SAE) code
- 4
- Auxiliary emission controls
- 43
- Specific fault
Questions drivers ask
Can I drive with code P0443?
Usually yes for a short time, if the car drives normally, the temperature gauge reads normal and the check engine light is steady. If the light flashes, the engine loses power or overheats, or other warning lights come on, pull over and have it checked.
Will my car pass an emissions inspection with P0443?
Probably not in states that test vehicles with an OBD-II scan: an emissions-related code that keeps the check engine light on is usually an automatic fail. Rules differ by state and county, so check yours.
Will P0443 clear by itself?
The light can go off after several drive cycles without the fault, but the code returns if the cause is still there. After a repair, the readiness monitors need a full drive cycle before an inspection.
Can I fix P0443 myself?
Often yes, with an OBD-II scanner and basic tools. Difficulty: easy. Start with the cheapest checks before replacing expensive parts.
Often reported together
Codes that owners mention in the same NHTSA complaints as P0443. They can point to a shared cause, so it's worth checking them together.
- P0135O2 Sensor Heater Circuit Bank 1 Sensor 15 complaints
- P0030HO2S Heater Control Circuit (Bank 1 Sensor 1)4 complaints
- P0031HO2S Heater Control Circuit Low (Bank 1 Sensor 1)4 complaints
- P0403EGR A Control Circuit/Open4 complaints
- P0458EVAP System Purge Control Valve A Circuit Low4 complaints
- P0489EGR A Control Circuit Low4 complaints
This page is general information, not a substitute for a professional diagnosis. Repair costs are rough estimates for parts and labor and vary by vehicle and region.