P0443: Evaporative emission system purge control valve circuit
An OBD-II trouble code meaning the engine computer has found a fault in the circuit of the valve that lets fuel vapour into the engine.
How to read it
P0443 is one of the standard OBD-II trouble codes stored when the check engine light comes on. SAE J2012, the standard that defines the codes, names it “Evaporative Emission System Purge Control Valve Circuit”; a generic list of OBD-II codes gives the same name.
Also searched as: code P0443, P0443 code.
Code names follow SAE J2012. Manufacturers add codes of their own, and the same code can have several causes: the vehicle’s service information or a qualified mechanic can say what it means for a particular car.
What the evaporative system monitor checks
The federal rule requires the system to detect any fuel vapour leak at least as large as one caused by a hole 0.040 inch across, and an absence of purge air flow from the evaporative system.
What the manual says to do
Ford’s F-150 manual says that if the indicator stays on, the vehicle should be serviced at the first available opportunity, and that continued driving with it on can mean higher emissions, lower fuel economy, rougher running and more costly repairs.
How the light goes out
Under the federal rule, the check engine light may go out once the fault has not come back during three trips in a row in which its monitor runs without finding it. The system may erase the stored code if the same code has not been registered again in at least 40 engine warm-up cycles.
More OBD-II trouble codes
- P0420: Catalyst system efficiency below threshold (bank 1)
- P0430: Catalyst system efficiency below threshold (bank 2)
- P0300: Random/multiple cylinder misfire detected
- P0301: Cylinder 1 misfire detected
- P0302: Cylinder 2 misfire detected
- P0303: Cylinder 3 misfire detected
- P0304: Cylinder 4 misfire detected
- P0305: Cylinder 5 misfire detected
Sources
- SAE J2012: Diagnostic Trouble Code Definitions (2002), SAE J2012, April 2002 (technically equivalent to ISO/DIS 15031-6), SAE International; published by Public.Resource.Org on the Internet Archive, Appendix B (powertrain DTCs)
- Generic OBD-II Trouble Codes (scanned reference list), Internet Archive (item generic-and-honda-trouble-codes), P0xxx list
- 40 CFR 86.1806-05, On-board diagnostics (2012 edition), 40 CFR 86.1806-05, US Government Publishing Office (Code of Federal Regulations), § 86.1806-05(b) and (c)
- 2020 F-150 Owner's Manual, Ford Motor Company, Instrument Cluster; On-Board Diagnostics (OBD-II)
Last reviewed September 27, 2026 by Rory Hansen. How we research