EGR system fault

DTC P1406 Exhaust Gas Recirculation (EGR) Position Sensor Performance
Circuit Description
The PCM monitors the EGR valve pintle position input to ensure that the valve responds properly to commands from the PCM and to detect a fault if the pintle position sensor and control circuits are open or shorted. If the PCM detects a pintle position signal voltage outside the normal range of the pintle position sensor, or a signal voltage that is not within a tolerance considered acceptable for proper EGR system operation, the PCM will set DTC P1406.
PCM - powertrain control module ,engine computer .
Diagnostic Aids
Check for the following conditions:
• Excessive deposits on EGR valve pintle or seat. 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 EGR actual 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 fault.
Important: If the EGR valve shows signs of excessive heat, check the exhaust system for blockage (possibly a plugged catalytic converter) using the Restricted Exhaust System Check.
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 occurs. This may assist in diagnosing the condition.

whats the year , make , model and engine code

This DTC says nothing about changing the sensor or the connector or pig tail ! It's a circuit voltage low code
P0405 - DPF EGR Sensor Circuit Low Voltage Detected See DTC P1400 Problem with wiring or PCM !
P1400 - DPF EGR Sensor Circuit Low Voltage Detected The EGR monitor checks the DPF EGR sensor signal to the PCM for low voltage. The test fails when the average voltage to the PCM drops to a voltage less than the minimum calibrated value.

• DPFEGR circuit short to GND
• Damaged DPF EGR sensor
• VREF short to GND
• Damaged PCM

A DPF EGR PID reading less than 0.2 volt with the key ON and engine OFF or running, indicates a hard fault.

cleanout egr valve and troutle body . Or replace egr with new one, clean, check vacumm lines , check for clogged check , depending on modle of car you can pippoint problem as some have a common part problem depeding with make of car. But all have to do with exaust system. Insufficient flow exaust flow. Im not an expert, all I know it is related to this, I have it myself so im googling it.

Ford EGR valve

The OBDII fault code P0401 means that the engine computer has detected that the Exhaust Gas Recirculation (EGR) system flow is insufficient. Read more how the EGR system works below. What could cause the code P0401 - clogged or restricted EGR passages
- faulty EGR valve
- EGR valve stuck closed
- problems with the DPFE sensor (Ford)
- problems with hoses to the DPFE sensor (Ford)
- problem with the EGR vacuum switching valve (Toyota)
- clogged catalytic converter
- carboned up EGR temperature sensor
- vacuum supply issues at the vacuum-operated EGR valve
- electrical problems with the EGR valve control circuit
- engine computer problems
helpful website helps you with pinpoint and sou;ution related to auto make and model shows you most common cause of code reading.
www.samarins.com

Hi there:
DTC P0403 - Exhaust Gas Recirculation Circuit Malfunction
The causes for a P0403 EGR code could be any of the following:
- Bad EGR solenoid

- Excessive resistance in control circuit (PCM controlled ground) due to an open, chafing or damage to the harness
- Poor connection at the EGR solenoid harness (worn or loose pins)
- Water intrusion at the EGR solenoid harness
- Blockage in EGR control solenoid holding solenoid open or closed causing excessive resistance
- Loss of supply voltage to EGR solenoid
- Bad PCM
DTC P0406 - Exhaust Gas Recirculation Sensor A Circuit HighAccording with the previous fault code, it's an electronic linear egr valve, you need a new one.

DTC P0108 - MAP Pressure Circuit High Input

Potential causes of a P0108 code:
- Bad MAP sensor
- Leak in vacuum supply line to MAP sensor
- Engine vacuum leak
- Short on signal wire to PCM
- Short on reference voltage wire from PCM
- Open in ground circuit to MAP
- Worn engine causing low vacuum


A good way to diagnose if the MAP sensor is to blame would be to compare the KOEO (key on engine off) MAP sensor reading on a scan tool with the Barometric pressure reading. They should be the same because they both measure atmospheric pressure.


If the MAP reading is greater than 0.5 volt off of the BARO reading, then replacing the MAP sensor would likely fix the problem. Otherwise, start the engine and observe the MAP reading at idle. It should normally be about 1.5 volts (varies according to altitude).


a. If it is, the problem is likely intermittent. Check all the vacuum hoses for damage and replace as necessary. You can also try wiggle testing the harness and connector to reproduce the problem.
b. If the scan tool MAP reading is more than 4.5 volts, check the actual engine vacuum reading with the engine running. If it is less than 15 or 16 in. Hg, then the PCM is probably not seeing enough vacuum (due to a worn engine, perhaps) for a given operating condition (which causes a higher than normal voltage signal to the PCM) and setting the code. Repair the engine vacuum problem and retest.
c. But, if the actual engine vacuum reading is 16 in. Hg or more, then unplug the MAP sensor. The scan tool MAP reading should indicate that there is no voltage present. Check that the ground from the PCM is intact and also that the MAP sensor connector and terminals are tight. If the connection is good, then replace the map sensor.
d. However if, with KOEO, & the MAP sensor unplugged, the scan tool shows a voltage reading, then there may be a short in the harness to the MAP sensor. Turn the ignition off. At the PCM unplug connector and remove the MAP signal wire from the connector. Re-attach the PCM connector and see if with KOEO, the scan tool MAP reading shows voltage. If it still does, replace the PCM. If not, check for voltage on the signal wire you just removed from the PCM. If there is voltage on the signal wire, find the short in the harness and repair.
Hope this helps; also keep in mind that your feedback is important and I`ll appreciate your time and consideration if you leave some testimonial comment about this answer.

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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

Potential causes of a P0405 code include:
Short to ground in EGR signal or Reference circuits
Short to voltage in EGR ground or signal circuits
Bad EGR valve
Bad PCM wiring issues due to chafing or loose terminals


Possible Solutions:
If you have access to a scan tool you can command the EGR valve on. If it responds and the feedback indicates the valve is moving properly then the problem may be intermittent. Sometimes in cold weather, moisture can freeze in the valve causing it to stick. After the vehicle warms up the problem may disappear. Carbon or other debris can lodge in a valve causing it to stick also

If the EGR valve doesn't respond to your commands with the scan tool, disconnect the EGR harness connector. Turn the key to on position, engine off (KOEO). Using a voltmeter, check for 5 volts on the reference wire to the EGR valve. If there is no 5 volts, is there any voltage at all? If there is 12 volts, then repair short to voltage in the 5 volt reference circuit. If there is no voltage connect a test light to battery voltage and probe the 5 volt reference wire. If the test light illuminates, the 5 volt reference circuit is shorted to ground. Repair as necessary. If the test light doesn't illuminate check for an open in the 5 volt reference circuit. Repair as necessary

If there is no apparent problem and there is no 5 volt reference, PCM may be at fault, however other codes will likely be present. If 5 volts are present on the reference circuit, jumper the 5 volts to the EGR signal circuit. Now the EGR position on the scan tool should read 100 percent. If it doesn't connect test light to battery voltage and probe the EGR signal circuit. If it illuminates, then the signal circuit is shorted to ground. Repair as necessary. If the light doesn't illuminate, check for an open on the EGR signal circuit. Repair as necessary.

If, after jumpering the 5 volt reference circuit to the EGR signal circuit the scan tool EGR position reads 100 percent, then check for poor terminal tension at the EGR valve connector. If the wiring is okay, replace the EGR valve.

Hope this helps.

DTC P0405 - Exhaust Gas Recirculation Sensor A Circuit Low

There are different designs of EGR (Exhaust Gas Recirculation) systems, but they all operate in a similar way. The EGR valve is a PCM (Powertrain Control Module) controlled valve that allows measured amounts of exhaust gasses to pass back into the cylinders to be burned with the air/fuel mixture. Since exhaust gas is an inert gas that displaces oxygen, injecting it back into the cylinder can lower combustion temperatures which helps to improve NOx (oxides of nitrogen) emissions. EGR isn't needed on cold startup or at idle. EGR is commanded on under certain conditions like startup or at idle. EGR is commanded on under certain conditions like partial throttle or decel depending on engine temperature and load, etc. Exhaust gasses are supplied to the EGR valve from an exhaust pipe or the EGR valve may be mounted directly in the exhaust manifold. When needed, the valve is commanded "on" allowing the gasses to pass into the cylinders. Some systems divert exhaust gasses directly into the cylinders while others simply inject it into the intake manifold where it is then pulled into the cylinders. while others simply inject it into the intake manifold where it is then pulled into the cylinders.

Some EGR systems are quite simple while others are a little more complicated. Electrically controlled EGR valves are directly controlled by the PCM. A wiring harness plugs into the valve itself and is commanded by the PCM as it sees the need. These can be 4 or 5 wire. Usually 1 or 2 grounds 12 volt ignition feed, a 5 volt reference circuit, and a feedback circuit. Other systems are vacuum controlled. These are quite simple. The PCM controls a vacuum solenoid which when activated, allows vacuum to travel to the EGR valve and open it. There should also be an electrical connector on this type of EGR valve for the feedback circuit. The EGR system feedback circuit allows the PCM to see if the EGR valve pintle is actually moving as it should. If the feedback circuit detects that the voltage is unusually low, or it's position is lower than it's commanded to be, P0405 may set.


Symptoms of a P0405 DTC may include:
MIL (Malfunction Indicator Lamp) illumination


Potential causes of a P0405 code include:
Short to ground in EGR signal or Reference circuits
Short to voltage in EGR ground or signal circuits
Bad EGR valve
Bad PCM wiring issues due to chafing or loose terminals


Possible Solutions:
If you have access to a scan tool you can command the EGR valve on. If it responds and the feedback indicates the valve is moving properly then the problem may be intermittent. Sometimes in cold weather, moisture can freeze in the valve causing it to stick. After the vehicle warms up the problem may disappear. Carbon or other debris can lodge in a valve causing it to stick also

If the EGR valve doesn't respond to your commands with the scan tool, disconnect the EGR harness connector. Turn the key to on position, engine off (KOEO). Using a voltmeter, check for 5 volts on the reference wire to the EGR valve. If there is no 5 volts, is there any voltage at all? If there is 12 volts, then repair short to voltage in the 5 volt reference circuit. If there is no voltage connect a test light to battery voltage and probe the 5 volt reference wire. If the test light illuminates, the 5 volt reference circuit is shorted to ground. Repair as necessary. If the test light doesn't illuminate check for an open in the 5 volt reference circuit. Repair as necessary

If there is no apparent problem and there is no 5 volt reference, PCM may be at fault, however other codes will likely be present. If 5 volts are present on the reference circuit, jumper the 5 volts to the EGR signal circuit. Now the EGR position on the scan tool should read 100 percent. If it doesn't connect test light to battery voltage and probe the EGR signal circuit. If it illuminates, then the signal circuit is shorted to ground. Repair as necessary. If the light doesn't illuminate, check for an open on the EGR signal circuit. Repair as necessary.

If, after jumpering the 5 volt reference circuit to the EGR signal circuit the scan tool EGR position reads 100 percent, then check for poor terminal tension at the EGR valve connector. If the wiring is okay, replace the EGR valve.

Hope this 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.

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