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
Hope helps (remember to rate and comment this answer).
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