For 1990-2009 cars

### Circuit Description

The exhaust gas recirculation (EGR) value consists of a pintle valve that moves by the use of an internal solenoid and an internal position sensor, potentiometer, used to determine pintle valve position. The engine control module (ECM) controls the solenoid by supplying it ground whenever exhaust gas needs to be recirculated into the intake manifold. The ECM monitors the EGR solenoid and position sensor circuit for correct voltage levels at certain times. Normal EGR sensor voltages range from 0.5-1 volts at a 0 percent commanded duty cycle up to 4.2-4.7 volts at a 100 percent commanded duty cycle. DTC P0409 sets when the actual EGR sensor signal position differs from the ECM desired sensor position, based on the duty cycle of the solenoid, greater than a calibrated amount for a certain length of time.

### Conditions for Setting the DTC

DTC P0409 will set if the EGR sensor signal position differs from the ECM desired sensor position greater than +/- 20 percent when:

• | The condition exists for longer than 10 seconds.

• | The EGR is being commanded ON.

DTC P0409 diagnostic runs continuously with the engine running.

DTC P0409 is a type B DTC.

### Diagnostic Aids

Important: If any other EGR sensor or EGR solenoid DTCs except P0401 or P0402 is also set, diagnose that DTC first.

Possible causes for DTC P0409:

• | Corrosion or resistance in the sensor connector or splice pack connectors. Normal EGR SENSOR values for a closed EGR valve should be within 0.5-1 volts.

• | The EGR valve is sticking.