What does the check engine code p0406 mean on my dodge caravan with a 3.3L engine?

P0406 - Exhaust Gas Recirculation Sensor A Circuit High
An improper voltage signal is sent to ECM through the valve

Early Models : The EGR valve control the amount of exhaust gas routed to the intake manifold. Vacuum is applied to the EGR valve in response to the throttle opening. The vacuum control the movement of the taper valve connected to the vacuum diaphragm in the EGR valve.



Late Models : The EGR volume control valve uses a step motor to control the flow rate of EGR from exhaust manifold. This motor has four winding phases. It operates according to the output pulse signal of the ECM. Two windings are turned ON and OFF in sequence. Each time an ON pulse is issued, the valve opens or closes, changing the flow rate. When no change in the flow rate is needed, the ECM does not issue the pulse signal. A certain voltage signal is issued so that the valve remains at that particular opening.



Symptoms
- Engine Light ON (or Service Engine Soon Warning Light)
- Engine hesitation

Possible causes
- Harness or connectors (EGR volume control valve circuit is open or shorted.)
- EGR volume control solenoid valve
- EGR temperature sensor and circuit

Possible solution
- Repair EGR harness or connector
- Replaced EGR volume control solenoid valve
- Replaced EGR volume control valve


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