OBD-II trouble code
P0487: Exhaust Gas Recirculation Throttle Control Circuit "A" Open
The engine computer commanded the EGR throttle actuator and no current flowed at all. The word "open" in the title is doing real work here — it rules out most of what people normally check on an EGR throttle, including the carbon cleaning that fixes its neighbour code.
Quick facts
- System
- Powertrain
- Category
- Emissions / EGR
- Severity
- Medium severity
- Drivable
- Usually safe to drive short-term
- Repair cost range
- $90 – $950
- DIY difficulty
- Intermediate DIY
What does P0487 mean?
An EGR throttle is not the same thing as an EGR valve. It is a plate in the intake tract, upstream of where recirculated exhaust joins, and its job is to restrict incoming fresh air slightly so that intake pressure falls below exhaust pressure and gas will actually flow the way the system needs it to. Diesels rely on it heavily because a diesel throttles nothing under normal running and therefore generates almost no intake vacuum of its own. Some heavily EGR-dependent gasoline engines use one as well.
What separates P0487 from every other code on that hardware is the last word of its title. This is not a generic circuit malfunction and not a performance complaint. The module energised its output, monitored the current flowing through it, and found none — the circuit is electrically dead. That single fact eliminates a large share of the usual suspects. A soot-bound throttle plate still conducts. A sticking shaft still conducts. A worn position sensor still conducts. None of them can produce an open circuit, which means the most common repair performed on EGR throttles — pulling the assembly and cleaning the carbon out of it — will not fix a P0487 and is the most frequently wasted labour on this code.
What remains is a short and testable list: an actuator motor whose winding has gone open internally, a broken conductor in the harness, a connector that was pushed together without latching, a terminal that has backed out of its housing while looking fully seated, or a failed driver in the module. One resistance measurement across the actuator's two control pins, with the connector unplugged, splits that list in half — a reading in the expected range clears the actuator and sends you to the harness, while an infinite reading condemns it.
The driveability picture surprises people. Many EGR throttle designs are sprung to sit wide open when nothing is energising them, on the sensible principle that an intake restriction which fails should fail out of the way. A throttle that is stuck open is a throttle that is not restricting anything, so the engine breathes normally and the car often drives exactly as it always did. The consequences are that EGR flow falls short, oxides of nitrogen rise, an emissions test will fail, and on some diesels the reduced EGR control shifts more work onto the particulate filter over time.
Common causes
- Open winding inside the EGR throttle actuator motor
- Broken conductor in the EGR throttle control harness, often near a heat source or a flex point
- Connector pushed together but never latched, most commonly after unrelated intake work
- Terminal backed out of the connector housing while appearing fully seated from outside
- Corrosion at the actuator connector interrupting the circuit entirely
- Blown fuse or open supply feeding the EGR throttle actuator
- Failed output driver inside the engine control module
- Aftermarket EGR delete or blanking hardware leaving the actuator disconnected
Symptoms
- Check engine light on with P0487 stored
- Often no change in how the vehicle drives, because a de-energised EGR throttle usually parks open
- Failed emissions or inspection test
- Reduced power or limp mode on some diesel applications
- Longer warm-up or reduced exhaust temperature on engines that use the throttle to build heat
- Additional EGR flow codes appearing over time as recirculation falls short
- Code that returns immediately on the next key cycle rather than after a drive
Diagnostic steps
- 1.Confirm the code's exact wording before starting. "Open" narrows the diagnosis to a circuit carrying no current, which excludes sticking, carbon, and position-feedback faults entirely.
- 2.Unplug the EGR throttle actuator and measure resistance across its two control pins. An infinite reading condemns the actuator; a reading within specification moves the diagnosis to the harness.
- 3.Inspect the connector before anything else is removed. Push it firmly together and confirm the latch clicks — an unlatched plug after prior intake work is a leading cause.
- 4.Pull gently on each wire at the back of the connector. A terminal that has backed out of its housing looks perfectly seated until it moves.
- 5.With the connector unplugged, check for continuity from each actuator pin back to the module connector to find a broken conductor.
- 6.Verify the actuator's supply fuse and feed voltage with the key on before condemning the motor.
- 7.Command the EGR throttle with a scan tool and watch for any movement at all. No movement together with an open reading is consistent; movement with the code stored suggests an intermittent connection.
- 8.Do not begin by removing and cleaning the throttle assembly. Carbon cannot create an open circuit, and this step is the most common wasted labour on the code.
Repair cost
$90 – $950
A connector that simply was not latched costs nothing beyond the diagnostic fee. Repairing a broken wire or replacing a backed-out terminal runs $120-$350. An EGR throttle actuator supplied as a separate part is $150-$400 in parts; where it is integral to the throttle body or EGR housing, the complete assembly is $250-$700 with 1-3 hours of labour depending on how far into the intake it sits. Diagnosis is typically $90-$160. Note that cleaning the assembly, often quoted first on EGR throttle complaints, does not address this particular code.
Estimate your repair
Run the numbers for your vehicle
Open the Repair Cost Estimator with throttle body replacement preselected. Adjust labor rate and vehicle category to fit your situation.
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.