P2143Exhaust Gas Recirculation Vent Control Circuit/Open
The control circuit for the EGR vent solenoid, which releases vacuum or pressure to let the EGR valve close, is open or not responding.
Definition
On EGR systems that use a vent valve, the PCM energizes a vent control solenoid to bleed off actuator vacuum or pressure so the EGR valve can return toward closed. P2143 sets when the PCM detects an open circuit or no current flow in that vent control circuit. Depending on the failure, EGR may remain stuck flowing (causing rough idle, stalling, or hesitation) or unable to modulate correctly, and the vehicle will show a MIL and can fail an emissions test for NOx or an EGR monitor fault.
Common causes
- Failed EGR vent control solenoid winding (open coil)
- Broken or chafed wire between the PCM and solenoid
- Corroded or disconnected solenoid connector
- Blown fuse or open feed supplying the solenoid
- PCM driver failure (rare)
Common misdiagnoses
- EGR valve replaced when only the vent solenoid circuit is faulty
- Vacuum lines replaced for an electrical open circuit
- PCM replaced without checking solenoid coil resistance
- DPFE or EGR position sensor replaced unnecessarily
Troubleshooting steps
1.Locate and identify the vent solenoid
Consult the vehicle-specific diagram; on vent-equipped systems it is plumbed opposite the EGR vacuum regulator solenoid.
2.Measure solenoid coil resistance
Compare to spec (commonly 20-100 ohms); an open reading confirms a failed solenoid.
3.Check power and PCM control at the connector
Verify switched voltage on the feed side and use a test light or scope to confirm the PCM pulls the control side low when commanded.
4.Inspect wiring between PCM and solenoid
Check continuity end-to-end; look for chafe points near the intake and harness brackets.
5.Command the solenoid and verify EGR response
With a bidirectional scan tool, actuate the vent solenoid and confirm the EGR valve or its position sensor responds appropriately.