Circuit Description
The exhaust gas recirculation (EGR) solenoid and pintle value assembly serve to reduce the temperature of combustion by introducing non-volatile exhaust gas into the combustion chambers. The EGR flow check diagnostic runs once per ignition cycle after 1.5 kg of air passed through the engine. The ECM compares the MAP sensor reading to a modeled value that it calculates. DTC P0401 will set if the measured value is less than a calibrated value of the modeled value.
DTC Parameters
DTC P0401will set if the measured manifold pressure is less than 70 percent of the calculated pressure (based on engine load and EGR position) when:
| • | Engine speed is between 1600 and 2200 RPM. |
| • | Engine load is between 35% and 65%. |
| • | Altitude is less than 9000 ft. |
DTC P0401 diagnostic runs once per ignition cycle for up to 15 seconds.
P0401 is a (type B) DTC.
Diagnostic Aids
DTC P0401 may set due to buildup around the EGR pintle valve bore opening restricting exhaust gas flow.
Diagnose other DTCs, especially a MAP DTC before diagnosing this DTC.
Possible causes:
| • | EGR valve stuck closed or carbon plugged. |
| • | EGR valve passage plugged restricted. |
