P0402

Wiring Diagram:

P0402- EGR FLOW EXCESSIVE
The exhaust gas recirculation (EGR) valve consists of a pintle valve, which moves by the use of an internal solenoid, and an internal position sensor (potentiometer) used to determine pintle valve position. The 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. The ECM also monitors the flow rate of exhaust gas through the EGR valve by using the MAP sensor. After certain conditions have been met, the ECM will compare the MAP sensor signal voltage change and its steady state value to a modeled MAP sensor signal value after the EGR valve has been commanded On. This once per ignition cycle test is based off of the narrow engine speed and load range listed under DTC parameters. DTC P0402 sets when the MAP sensor signal voltage changes or its steady state value is above a certain threshold (indicating too much change in intake manifold pressure) when the EGR valve is commanded to a certain duty cycle.

DTC PARAMETERS
DTC P0402 will set if the ECM determines EGR flow to be excessive by comparing the MAP sensor signal voltage change along with a steady state value to a modeled value when:
^ Condition exists for longer than 9 seconds continuously or for a total of 9 seconds up to three independent tests
^ EGR solenoid is commanded to a 60% duty cycle
^ Engine speed is between 1600 and 2200 rpm
^ Engine load is between 35% and 65%
^ Engine load change rate is less than 0.35%
^ Accumulated air mass is greater than 0.5 kg since engine start
^ Altitude is less than 2750 meters (9023 ft.)

DTC P0402 diagnostic runs once per ignition cycle up to 9 seconds once the above conditions have been met. However, the diagnostic may take only three seconds to pass.

P0402 is a type B DTC

DIAGNOSTIC AIDS

IMPORTANT: If any MAP, EGR sensor or EGR solenoid DTCs are also set, diagnose those DTCs first.

This DTC may set if the MAP sensor air tube is plugged or partially plugged or if the sensor has a leak around the sealing grommet.

NOTE: It takes up to a 40% or more duty cycle to make the EGR valve move.

Remove EGR valve and check EGR gasket for damage and EGR passage for carbon pieces that may have gotten caught in the EGR valve causing it to stick. Clean debris if any is found, then replace EGR valve.