Exhaust Gas Recirculation Throttle Position Control Circuit
Your engine's EGR valve control isn't communicating properly with the computer. Think of it like a stuck throttle on a bicycle—the brake system knows something is wrong, but can't adjust it correctly.
The ECM monitors the EGR throttle control circuit voltage and resistance to ensure proper position feedback. It expects a linear voltage signal between 0.5V and 4.5V as the valve opens and closes. A fault occurs when the signal falls outside expected parameters or shows no response to commanded positions.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| EGR Throttle Position Voltage | 0.5V to 4.5V (proportional to position) | Below 0.5V or above 4.5V, or no change during command |
| Circuit Resistance | 50–150 ohms (wiring integrity) | Open circuit (infinite ohms) or short to ground (near 0 ohms) |
Code P0487 is a moderate fault. You can generally drive to a workshop, but avoid long trips or high-load driving (motorway, uphill towing) until it is diagnosed. If the code keeps returning after clearing, or if you notice the symptoms listed above worsening, do not delay professional diagnosis. Many moderate codes have multiple possible root causes — a mechanic with live OBD data can identify the exact fault more efficiently than part-by-part trial and error.
Once the fault is repaired, P0487 can be cleared using any OBD-II scanner. Connect the scanner, navigate to "Clear Codes" or "Erase DTCs," and confirm. The check engine light turns off immediately.
The code will return if the root cause was not actually fixed. The ECM re-detects the fault within 1–3 drive cycles and sets the code again.