OBD codes / P0406
P0406
ModerateExhaust Gas Recirculation Sensor A Circuit High
P0406 is generally safe to drive with short-term — it's mainly an emissions code. If you feel pinging under load, address it sooner. It will fail an emissions test until fixed. Check the wiring and connector before replacing the sensor.
What this code means
The EGR position sensor tells the computer how far the EGR valve is open. P0406 means that sensor's signal is reading too high. The usual causes are a failed EGR position sensor, a wiring fault (open or shorted high), or a corroded connector. On many EGR valves the position sensor is built into the valve, so the repair can mean replacing the valve assembly. It's mostly an emissions issue and rarely changes how the car drives.
Symptoms you might notice
- Check-engine light, usually with no obvious change
- Occasional rough idle or light pinging under load
- Failed emissions test
What it costs to fix
Typical range: $60–$400 · about ~0.3–1.5 hrs of labor
| If the cause is… | Part | Labor |
|---|---|---|
| EGR position sensor | $25–$100 | ~0.3–1 hrs |
| EGR valve (sensor integrated) | $50–$300 | ~0.5–1.5 hrs |
| Wiring / connector repair | $10–$120 | ~0.5–1.5 hrs |
A standalone position sensor is cheap. The cost rises only if the sensor is built into the EGR valve and the whole valve is replaced. A wiring/connector fix is inexpensive once located.
The price swings on which cause it turns out to be — so confirm the cause before paying. Diagnose P0406 for my exact vehicle →
Frequently asked
Can I drive with P0406?
Usually yes, short-term — it's primarily an emissions code. Address any pinging sooner, and plan to fix it before an emissions test.
Is P0406 the sensor or the valve?
Often the EGR position sensor or its wiring. On valves where the sensor is built in, the repair may mean the whole valve assembly. Checking the wiring first can save replacing a part that was fine.
What does 'circuit high' mean for P0406?
The EGR position sensor's voltage is at the high end, which usually means a failed sensor or a wire shorted high rather than a real valve position. Diagnosis confirms which.
How much does it cost to fix P0406?
Inexpensive if it's a standalone sensor or wiring; more if the sensor is integrated into the EGR valve and the valve is replaced. Check the connector before buying parts.
Seeing P0406 on your car? Get a diagnosis specific to your exact year, make and model.
Diagnose P0406 for my vehicleGeneric OBD-II reference. Manufacturer-specific behavior varies — confirm with a scan tool and, for safety-related codes, a professional inspection.