P0406 — Exhaust Gas Recirculation Sensor A Circuit High
Category: Powertrain Severity: Low
Updated:
DTC code P0406 means: Exhaust Gas Recirculation Sensor A Circuit High. It falls under the "Powertrain" category, with an estimated severity of Low. Common causes include faulty EGR valve stuck open or malfunctioning, faulty EGR position sensor and wiring/connector issue; it's worth confirming the diagnosis before replacing parts.
Possible causes
- Faulty EGR valve stuck open or malfunctioning
- Faulty EGR position sensor
- Wiring/connector issue
- Carbon buildup affecting valve movement
Symptoms
- Rough or unstable idle
- Engine hesitation or stalling
- Check engine light on
- Possible failed emissions test
How to diagnose it step by step
- Check the position sensor ground.
- Check the wiring.
- Replace the EGR valve.
How to fix it
Check the EGR valve for carbon buildup that could keep it stuck; clean or replace it if needed. Test the position sensor and its wiring separately before assuming the valve itself is bad.
Estimated repair cost
$200–650.
Frequently asked questions
What does DTC code P0406 mean?
Exhaust Gas Recirculation Sensor A Circuit High.
Is code P0406 serious?
Severity Low. Usually a minor fault; check the causes listed.
Can I keep driving with code P0406?
Yes, carefully.
Related codes
P0405 P0404 P0403 P0402 P0401 P0400 P0410 P0411 P0420 P0421
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