What is this code p1401

Did you use a genuine replacement sensor. I ask this because aftermarket sensors have different parameters (settings) to original and the cpu still thinks there is a fault

Sounds like the EGR valve is sticking open.

Codes don't have a certain location, a code means a problem has occurred in a system of the electronics of the cars fuel control or emission control system.
P1401 NISSAN - EGR Temperature SensorPossible causes- EGR Temperature Sensor harness is open or shorted
- EGR Temperature Sensor circuit poor electrical connection
- Faulty EGR Temperature Sensor
- Malfunction of EGR function, EGRC-BPT valve or EGRC-solenoid valve
- Blocked EGR passages When is the code detected?An excessively low voltage from the Exhaust Gas Recirculation (EGR) temperature sensor is sent to Engine Control Module (ECM) even when engine coolant temperature is low, or an excessively high voltage from the EGR temperature sensor is sent to ECM even when engine coolant temperature is high.
P1401 NISSAN Description The Exhaust Gas Recirculation (EGR) temperature sensor detects temperature changes in the EGR passage way. When the EGR valve opens, hot exhaust gases flow, and the temperature in the passage way changes. The EGR temperature sensor is a thermistor that modifies a voltage signal sent from the Engine Control Module (ECM). This modified signal then returns to the ECM as an input signal. As the temperature increases, EGR temperature sensor resistance decreases.
This sensor is not used to control the engine system. It is used only for the on board diagnosis

CODE P1401 IS SENSOR CIRCUIT HIGH INPUT. POSSIBLE CAUSES DPFE SENSOR SIGNAL CIRCUIT IS OPEN.DPFE SENSOR GROUND CIRCUIT IS OPEN.DPFE SENSOR SIGNAL IS SHORTED TO VREF 5V. DPFE SENSOR IS DAMAGED OR IT HAS FAILED. PCM HAS FAILED.******* WHEN YOU SEE CODE P1401 FLASHING ********** WHAT IS HAPPENING ENGINE RUNNING AND THE PCM DETECTED THE DPF EGR SENSOR SIGNAL WAS MORE THAN THE MAXIMUM CALIBRATED VALUE OF 4.5 VOLTS. ON THIS VECHICLE APPLICATION THE DPPE EGR VALVE AND EVR SOLENOID ARE INTEGRATED INTO THE ESM ASSEMBLY.

P1401 - DPFE Circuit High Input

Description Of The Code:
The EGR monitor checks the DPF EGR sensor signal to the PCM for high voltage. The test fails when the average voltage to the PCM goes to a voltage greater than the maximum calibrated value.

Possible Causes:

DPF EGR circuit open.

VREF short to PWR.

Damaged DPF EGR sensor.

DPFEGR circuit short to PWR.

SIG RTN circuit open.

Damaged PCM.

Possible Solution:
A DPF EGR PID reading greater than 4.5 volts with the key ON and engine OFF or running indicates a hard fault.

no-this should not... dpef is just a emission control device and usually will have no symptoms.

P1401 - DPFE EGR CIRCUIT HIGH INPUT

Your DPFE is no good hate to say but probably was your proplem the whole time none of the other parts not needed except the fuel filter and pcv good PM stuff there. The DPFE is either going to be a silver or black box around where the egr valve is. be sure not to get the hoses crossed when putting it back on.

Keep us updated.

The P1401--EGR Sensor Circuit High Voltage Detected
I can not tell you what the problem is,without the vehicle and doing some tests.

The P1944- I don't have,but it apears to be,as you were told, trans related. Maybe an output sensor on trans?

Theses auto stores don't help much,by pulling codes and leaving you hanging.

What problems are you having? Obviously,drivability and shifting.

Differential Pressure Feedback Electronic Sensor circuit High Voltage. Sensor could be bad, check for water inside of sensor, also check the vacuum hose going to it.

Check the pipe that feeds the DPFE for cracks, if that's ok, check the Engine's back pressure at the front O2 sensor port. It should have no more than about 1 lb of back pressure max. If it's higher, you may have a faulty cat converter. (they're not cheap) When they go they sometimes plug the muffler with debris.