2000mazda b2500 2.5l rough idle dpfe sensor circuit high voltage signal p1401 code

The P1401 code could be for anything Egr related. Usually it is a defective DPFE (differential pressure feedback Exhaust) But, it can also be caused by a defective EGR valve or EVR (Exhaust Valve Regulator) solenoid/switch. --or an air leak at any part of the system including the silicone hoses that feed the DPFE/

Exhaust gas recirculation module check:


1. Note the Differential Pressure Feedback Exhaust Gas Recirculation (DPFE) sensor voltage through the scan tool or backprobe the Brown/Light Green (BN/LG) wire of the Exhaust Gas Recirculation System Module (ESM). Voltage should indicate a reading of 0.5-1.2 volts.

2. If the voltage of the DPFE sensor is out of range, low or high, disconnect the ESM and note that the voltage of the DPFE sensor circuit should indicate a reading of 5.0 volts.

3. If the DPFE sensor voltage is out of range connected and the reading shows 5.0 volts with the ESM disconnected, reconnect the ESM and verify that the Brown/White (BN/WH) wire shows a 5.0 volt reading and that the Grey/Red (GY/RD) wire shows to be a good ground, indicating a voltage of less than 0.1 volts. If these circuits check to be ok, replace the ESM due to a faulty DPFE sensor.

4. If the DPFE sensor voltage in step 1 is found to be ok, verify that both vacuum hoses to the ESM have full engine vacuum to them when it's running.

5. With the engine idling, backprobe the Brown/Pink (BN/PK) wire and hold it to ground. This should activate the Exhaust Gas Recirculation Vacuum Regulator (EVR) solenoid of the ESM. The EGR valve should open, the engine should run rough, and the DPFE sensor voltage should climb.

6. Replace the ESM for a faulty EGR valve, EVR solenoid, or DPFE sensor if the DPFE sensor or engine does not respond to ground activation of the BN/PK wire

Sounds like the EGR valve is sticking open.

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.

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.

DTC P0401 - Insufficient EGR Flow

EGR stands for Exhaust Gas Recirculation. It is part of the vehicle emmissions system, and is used to reduce combustion temperature and pressure to control Oxides of Nitrogen. There are generally three parts to the EGR system: the EGR valve, an actuator solenoid, and a differential pressure sensor EGR (DPFE). These things work together to deliver the correct amount of recirculation based on engine temperature, load, etc. The P0401 code means that OBD detected an insufficient amount of EGR.

Causes: A code P0401 most likely means one or more of the following has happened:
* The DPFE (differential pressure feedback EGR) sensor is faulty and needs to be replaced
* There is a blockage in the EGR (tube), most likely carbon buildup
* The EGR valve is faulty
* The EGR valve may not be opening due to a lack of vaccuum

Possible Solutions: In fixing this code, it is quite common for people to just replace the EGR valve only to have the OBD code return. The EGR valve is not always the culprit.
* Use a vacuum pump and pull the EGR valve open while monitoring engine RPM's & DPFE voltage. There should be a noticable difference in RPM's with the EGR open
* Clean out the EGR valve and/or tubing to remove deposits
* Check the voltage at the DPFE, compare to specified values (refer to a repair manual for your specific model)
* Replace the DPFE sensor (with a good quality / OEM one)
* Replace the EGR valve


DTC P1401 - Differential Pressure Feedback Electronic Sensor circuit High Voltage

I think that you need a new DPFE; first check it, you could also have something restricted. There are ports in the throttle body that can cause this as well. Check THIS LINK.

Hope helps.

Answer P1401 - DPF EGR Sensor Circuit High Voltage Detected The EGR monitor checks the DPFE 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: DPFE circuit open VREF short to PWR Damaged DPFE sensor DPFE circuit short to PWR SIGNAL RTN circuit open Damaged PCM Look at scan data stream for a reading greater than 4.5 volts with the key ON and engine OFF or running. This indicates a hard fault.

Exhaust gas recirculation flow reduced. Could be caused by valve or gunk in the flow path. I'll paste a little bit about troubleshooting below. If you need specific instructions for repairing your system, please reply with your engine size/type.

The Exhaust Gas Recirculation (EGR) system is designed to reintroduce exhaust gas into the combustion chambers, thereby lowering combustion temperatures and reducing the formation of Oxides of Nitrogen (NO x ).
The amount of exhaust gas that is reintroduced into the combustion cycle is determined by several factors, such as: engine speed, engine vacuum, exhaust system backpressure, coolant temperature, throttle position. All EGR valves are vacuum operated. The EGR vacuum diagram for your particular vehicle is displayed on the Vehicle Emission Control Information (VECI) label.
The EGR system is Differential Pressure Feedback EGR (DPFE) system, controlled by the Powertrain Control Module (PCM) and composed of the following components: DPFE sensor (also referred to as the backpressure transducer), EGR Vacuum Regulator (EVR) solenoid, EGR valve, and assorted hoses.

COMPONENT TESTING

DPFE Sensor

1. Disconnect the pressure hoses at the DPFE sensor.
2. Connect a hand vacuum pump to the downstream pickup marked REF on the sensor.
3. Using a multimeter, backprobe the SIG RTN circuit at the DPFE connector.
4. With the ignition ON , signal voltage should be 0.20-0.70 volts.
5. Apply 8-9 in. Hg of vacuum to the sensor. Voltage should be greater than 4 volts.
6. Quickly release the vacuum from the sensor. Voltage should drop to less than 1 volt in 3 seconds.
7. If the sensor does not respond as specified, check the power and ground circuits.
8. If power and ground circuits are functional, the sensor is faulty.

EGR Valve Control Solenoid

1. Remove the EVR solenoid.
2. Attempt to lightly blow air into the EVR solenoid.
   1. If air blows through the solenoid, replace the solenoid with a new one.
   2. If air does not pass freely through the solenoid, continue with the test.
   
   
3. Apply battery voltage (approximately 12 volts) and a ground to the EVR solenoid electrical terminals. Attempt to lightly blow air, once again, through the solenoid.
   1. If air does not pass through the solenoid, replace the solenoid with a new one.
   2. If air does not flow through the solenoid, the solenoid is OK.
   
   
4. If the solenoid is functional but the problem still exists, check the power and ground circuits.

EGR Valve

1. Install a tachometer on the engine, following the manufacturer's instructions.
2. Detach the engine wiring harness connector from the Idle Air Control (IAC) solenoid.
3. Disconnect and plug the vacuum supply hose from the EGR valve.
4. Start the engine, then apply the parking brake, block the rear wheels and position the transmission in Neutral.
5. Observe and note the idle speed.

If the engine will not idle with the IAC solenoid disconnected, provide an air bypass to the engine by slightly opening the throttle plate or by creating an intake vacuum leak. Do not allow the idle speed to exceed typical idle rpm.

1. Using a hand-held vacuum pump, slowly apply 5-10 in. Hg (17-34 kPa) of vacuum to the EGR valve nipple.
   1. If the idle speed drops more than 100 rpm with the vacuum applied and returns to normal after the vacuum is removed, the EGR valve is OK.
   2. If the idle speed does not drop more than 100 rpm with the vacuum applied and return to normal after the vacuum is removed, inspect the EGR valve for a blockage; clean it if a blockage is found. Replace the EGR valve if no blockage is found, or if cleaning the valve does not remedy the malfunction.
   
   

Check the EGR valve for functioning:

COMPONENT TESTING DPFE Sensor

1. Disconnect the pressure hoses at the DPFE sensor.
2. Connect a hand vacuum pump to the downstream pickup marked REF on the sensor.
3. Using a multimeter, backprobe the SIG RTN circuit at the DPFE connector.
4. With the ignition ON, signal voltage should be 0.20-0.70 volts.
5. Apply 8-9 in. Hg of vacuum to the sensor. Voltage should be greater than 4 volts.
6. Quickly release the vacuum from the sensor. Voltage should drop to less than 1 volt in 3 seconds.
7. If the sensor does not respond as specified, check the power and ground circuits.
8. If power and ground circuits are functional, the sensor is faulty.

EVR Solenoid

1. Remove the EVR solenoid.
2. Attempt to lightly blow air into the EVR solenoid.
   1. If air blows through the solenoid, replace the solenoid with a new one.
   2. If air does not pass freely through the solenoid, continue with the test.
3. Apply battery voltage (approximately 12 volts) and a ground to the EVR solenoid electrical terminals. Attempt to lightly blow air, once again, through the solenoid.
   1. If air does not pass through the solenoid, replace the solenoid with a new one.
   2. If air does not flow through the solenoid, the solenoid is OK.
4. If the solenoid is functional but the problem still exists, check the power and ground circuits.

EGR Valve

1. Install a tachometer on the engine, following the manufacturer's instructions.
2. Detach the engine wiring harness connector from the Idle Air Control (IAC) solenoid.
3. Disconnect and plug the vacuum supply hose from the EGR valve.
4. Start the engine, then apply the parking brake, block the rear wheels and position the transmission in Neutral.
5. Observe and note the idle speed. NOTE: If the engine will not idle with the IAC solenoid disconnected, provide an air bypass to the engine by slightly opening the throttle plate or by creating an intake vacuum leak. Do not allow the idle speed to exceed typical idle rpm.
   
6. Using a hand-held vacuum pump, slowly apply 5-10 in. Hg (17-34 kPa) of vacuum to the EGR valve nipple.
   1. If the idle speed drops more than 100 rpm with the vacuum applied and returns to normal after the vacuum is removed, the EGR valve is OK.
   2. If the idle speed does not drop more than 100 rpm with the vacuum applied and return to normal after the vacuum is removed, inspect the EGR valve for a blockage; clean it if a blockage is found. Replace the EGR valve if no blockage is found, or if cleaning the valve does not remedy the malfunction. ---