P0406 EGR sensor A circuit high
What P0406 means
The engine control unit sees a voltage from the exhaust gas recirculation (EGR) feedback sensor that is above its normal range. The ECU can no longer trust the EGR valve position and may switch EGR off.
P0406 is a generic SAE J2012 code: it means the same on every make. The exact cause still depends on the car, so read the freeze-frame data before replacing parts.
At a glance
- Severity
- Medium
- Typical repair cost
- 60–400 €
- Workshop time
- 0.3–2 h
- Repair difficulty
- Medium
- DIY possible
- Yes
- Check engine light
- Yes
- Affects emissions test
- Yes
Parts and labour at an independent workshop in Europe. Main dealers charge more; the cause decides the bill, not the code.
Symptoms
- Check engine light on
- Possible rough idle or hesitation
- Higher emissions at technical inspection
Common causes
- Faulty EGR position sensor or EGR valve assembly
- Open ground circuit to the sensor
- Signal wire shorted to a voltage source
- Corroded or loose connector
Can I keep driving with P0406?
You can keep driving, but have it checked within one to two weeks.
What to check first
- Inspect the connector and wiring at the EGR valve
- Check the sensor ground and the signal voltage with the valve closed
- Look for a short to voltage in the signal wire
- Replace the sensor or EGR valve if the circuit is good
Related codes
- P0405 EGR sensor A circuit low
- P0404 EGR A control circuit range/performance
- P0403 EGR A control circuit/open
- P0402 EGR flow excessive detected
- P0401 Exhaust gas recirculation (EGR) A flow insufficient
- P0400 Exhaust gas recirculation (EGR) A flow malfunction
- P0410 Secondary air injection system A
- P0411 Secondary air injection system incorrect flow detected
Data: TORKO fault-code catalogue, built on OBDex (CC0-1.0) and reviewed against workshop practice. Informational only — it does not replace a diagnosis by a mechanic.
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