OBD-II trouble code
P2145: Exhaust Gas Recirculation Vent Control Circuit High
One code, two completely different repairs. A high reading means the module could not pull the control line down, and that happens either because the circuit is broken or because it is tied to power — a five-dollar terminal fix and an hours-long harness trace, told apart by a single resistance measurement before anything is bought.
Quick facts
- System
- Powertrain
- Category
- Emissions / EGR
- Severity
- Medium severity
- Drivable
- Usually safe to drive short-term
- Repair cost range
- $60 – $500
- DIY difficulty
- Intermediate DIY
Browse every code in P2100–P2199, or start from the full code library.
What does P2145 mean?
P2145 is stored when the module commands the recirculation vent solenoid on, looks at the control terminal expecting it to fall close to zero volts, and finds it still sitting up near battery voltage. The module can only report what it measured. It cannot tell you why, and the reason this page exists is that there are two unrelated reasons, they cost very different amounts to fix, and the code does not distinguish between them.
The first is an open circuit. A broken conductor, a corroded terminal, an unlatched connector or an open solenoid winding all leave the module's driver with nothing to pull down against, so the measured voltage never moves. The second is a short to a powered wire. Here the conductor is intact, but something upstream is feeding battery voltage into the line and the module's driver cannot win against it, so again the voltage refuses to fall. The symptom is identical. The measurement is identical. The repairs are not remotely alike.
Sorting them takes one test, and it should happen before a single part is ordered. Unplug the solenoid and measure resistance across its two terminals. A healthy solenoid of this type reads a specific low resistance, typically in the tens of ohms. An infinite reading means the winding is open and the solenoid is the fault, full stop. A normal reading means the solenoid is fine and the problem is in the harness — at which point you unplug the module connector too and check whether the control wire has voltage on it with everything disconnected. Voltage present with both ends off the circuit is a short to power and nothing else, and now you know you are looking for a chafe rather than a break.
That matters commercially, because the reflex on this code is to buy the solenoid. It is cheap, it is accessible, and it is named in the code description, so it gets replaced first. When the winding measured normal, replacing it achieves nothing except a part in the bin and a customer who now believes the diagnosis was guesswork. The resistance check costs nothing and prevents that outcome entirely.
There is a third possibility that is not a fault at all, and it is common enough to check before anything else. If the solenoid is simply unplugged, the module sees exactly the open circuit described above and sets this code. Connectors get left off after intake work, timing work, turbo work, injector work — anything that required the harness to be moved aside. Before diagnosing a car that has recently been in a workshop, look at the connector and make sure it is mated and latched. A surprising share of these codes end there.
As for how the vehicle behaves, a solenoid that cannot be energised is a vent that never opens, and the consequences follow from that. Vacuum admitted to the recirculation valve's diaphragm has no route out, so the valve hangs part open after it has been told to close. That is a rough, hunting idle, a stumble pulling away, and stalling at junctions and in slow traffic, with the vehicle behaving normally at cruise. It is the same driveability picture that an open on this circuit has always produced, so P2145 and a stored open-circuit code on the same solenoid frequently appear together and describe the same underlying situation from two angles.
Where the short-to-power case is concerned, geography is worth knowing. The solenoid's control wire and its own fused positive feed usually travel in the same bundle for at least part of the route, because they both terminate at the same two-pin connector. A single chafe inside that bundle can therefore short the control wire to the very supply that powers the device it controls, which produces this code with no other circuit in the car affected. That is why a careful inspection of the last few inches of harness before the connector is more productive than a full-length trace, and it is where to start.
Common causes
- Solenoid connector left unmated or unlatched after other work in the area
- Open winding inside the vent solenoid or vacuum regulator assembly
- Broken conductor in the control wire, often just behind the connector where the harness flexes
- Corroded or spread terminal that has lost contact inside the connector body
- Control wire chafed through to its own positive feed inside the shared two-wire bundle
- Control wire shorted to another switched or fused supply where the harness crosses a bracket
- Damaged or pushed-out terminal from a previous probe or a forced connector
- Repair splice made to the wrong wire, joining control to a power feed
- Connector seal hardened with age, letting moisture corrode the pins open
- Module output driver failed open, which is uncommon and should be the last conclusion
Symptoms
- Check engine light with a recirculation vent control circuit high code stored
- Rough or hunting idle that clears as soon as engine speed comes up
- Stalling when coming to a stop, at junctions or in slow-moving traffic
- Stumble or hesitation pulling away from rest
- Normal power and normal manners at steady cruise
- An open-circuit code on the same vent solenoid stored alongside this one
- Recirculation valve that does not close fully when commanded shut with a scan tool
- Idle that is noticeably worse once the engine is fully warmed up
- Failed emissions test on a vehicle whose only real complaint is the idle
- Symptoms that appeared immediately after unrelated work under the bonnet
Diagnostic steps
- 1.Look at the connector first and confirm it is fully seated and latched. An unplugged solenoid produces this exact code, and recent work in the area makes that the single most likely explanation.
- 2.Unplug the solenoid and measure resistance across its terminals. An infinite reading condemns the solenoid outright; a normal reading of a few tens of ohms clears it and sends you into the harness.
- 3.With the solenoid still unplugged and the module connector also disconnected, check for voltage on the control wire. Voltage present with both ends off the circuit is a short to power and rules out an open.
- 4.If there is no voltage and no continuity, check the control wire end to end for an open, then repeat the check with the harness flexed, since a broken strand inside intact insulation can read connected at rest.
- 5.Concentrate the chafe search on the last stretch of harness before the connector, where the control wire and the solenoid's own positive feed run together and a single rub-through shorts one to the other.
- 6.Inspect the terminals themselves for spread contacts, push-out or corrosion, and drag-test each one with a matching pin rather than judging by eye.
- 7.Verify the positive feed to the solenoid is present and fused correctly, so a genuine open in the supply is not mistaken for a control-side problem.
- 8.Once the circuit is sound, command the solenoid on and off with a scan tool while back-probing the control terminal and confirm the voltage actually swings to near zero on command.
- 9.Confirm the vent bleeds vacuum mechanically when energised, because the electrical repair fixes the circuit and not a blocked atmospheric port, and a blocked port produces the same idle complaint with no code at all.
- 10.Road test after clearing and verify the idle complaint is gone rather than only that the code has not returned, since the code can stay away while a partly open valve keeps stalling the car.
Repair cost
$60 – $500
The cheapest outcome is genuinely free: a connector that was left off costs nothing but the time to notice it. Diagnosis where the fault is real is $100 to $220. An open winding means a vent solenoid or vacuum regulator at $40 to $180 in parts plus 0.4 to 1.5 hours, so $110 to $350 complete. A terminal repair or a single splice behind the connector is $80 to $200. A short to power that has to be chased through a bundle running along the top of the engine is the expensive version at $200 to $450, because the whole cost is labour spent unwrapping loom. Order the resistance check before the part and the wasted-solenoid outcome — a common $120 mistake on this code — disappears.
Estimate your repair
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DIY vs shop
This is an intermediate DIY job. It usually involves diagnostic steps, specialty parts, and some careful work in tight spaces. If you have the tools and a service manual or trustworthy video for your specific vehicle, it is achievable in a weekend. Otherwise, a competent independent shop will be faster.