P0401 OBD Trouble Code

Exhaust Gas Recirculation "A" Flow Insufficient Detected

EGR System Fault Conditions

Engine speed from 1900-2400 rpm, ECT sensor input over 170°F, closed loop enabled, throttle at off-idle, MAP in mid-range, VSS over 3 mph, then with the EGR test enabled, the PCM detected that the measured change in SHRTFT compensation value shift during the EGR Flow Rate Test was less than 7.4%, or that it was more than 20%.

EGR Insufficient Flow Detected Conditions

Engine running in steady state driving conditions (closed loop), then the PCM detected that the signal from the DPFE sensor indicated insufficient EGR gas flow.

EGR Flow Insufficient Conditions

No CKP, ECT, EGR Pintle, Fuel Injector, IAC, IAT, MAF, MAP, Misfire, TP or VSS codes set, ECT input more than 167°F, BARO input more than 70 kPa, throttle angle below 1%, engine speed 900-1400 rpm, A/C clutch status unchanged, EGR position less than 1%, VSS input over 25 mph, Transmission status unchanged, MAP, RPM, TP and VSS all steady, then the PCM detected the change in the MAP input in the test was too small for 2 seconds.