Check for the following conditions:
- Open EGR ignition filter circuit. An open in the EGR ignition filter circuit will cause erratic EGR Position Error readings while the EGR valve is operating. With the ignition ON, a test light should illuminate when connected between ground and the EGR ignition filter circuit at the PCM connector. If not, locate and repair the open in the EGR ignition filter circuit.
- pink wire pin 68 PCM connector C1(blue)
- Excessive deposits on EGR valve pintle or seat. Remove the EGR valve and check for deposits that may interfere with the EGR valve pintle extending completely or cause the pintle to stick.
- Poor connection or damaged harness. Inspect the wiring harness for damage. If the harness appears to be OK, observe the Actual EGR position display on the scan tool while moving connectors and wiring harnesses related to the EGR valve. A change in the display will indicate the location of the malfunction.
- EGR Valve Icing. EGR valve icing can occur during cold ambient conditions. An EGR valve icing condition will affect EGR system operation by causing the pintle to stick in the closed position. If DTC P1406 sets, EGR system operation may be inhibited for the remainder of the trip.
Reviewing the Fail Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to be set