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Keep Getting PO401 code even with new EGR Valve and getting 5V on reference circuit (D) and 12 Volts on the ground circuit (E). Note: No movable parts on the EGR Valve.

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  • Cars & Trucks Master
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Posted on Oct 14, 2013

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SOURCE: I have a 99 Windstar 3.8L Keep getting DTC PO401

Does the egr vavle open ? You will need to use a scanner to test the dpfe voltage when the egr valve is energized you should read around 3.5 4.00 volts. Also you could remove the vacume line from the egr valve and with the engine running you should see around 100 rpm drop in engine rpm at least this would indicate the egr valve is capable of flowing egr gases through the system to the cylinders.

Posted on May 30, 2010

pchambley
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SOURCE: OBD II code PO401 EGR Problem? Change Solenoid and

The EGR solenoid hardley ever goes out..Probably a flow problem,,If its the 4.2 its more than likely the EGR ports...Please list the engine..I may know what to tell you to fix it..

Posted on Sep 14, 2011

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Code PO401


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

Nov 10, 2013 | 2004 Ford Explorer

2 Answers

Is there a "computer flash update" for my 2001 isuzu rodeo ls 3.2l (v-6)


code p1120 refers tothrottle position sensor1--circuit malfunction---causes ---wiring open cuircuit--/short circuit to ground/short circuit to positive---throttlecontrol unit---ECM
code p0401 refers to exhaust gas recirculation(EGR) valve system---insufficient flow detected. ---causes hose leak/blockage--basic setting not carried out (if applicable)---wiring---EGR valve---EGR solenoid----ECM. I would replace the EGR valve for starters Get unit from the wreckers. You may have to have the CPu reset with a code reader tool

Mar 31, 2013 | 2001 Isuzu Rodeo

1 Answer

OBD II code PO401 EGR Problem? Change Solenoid and pressure sensor; egr valve working good. Pressure sensor have 5 volt reference and ground; solenoide have 12 volt in red cable and negative is ok. Ford...


The EGR solenoid hardley ever goes out..Probably a flow problem,,If its the 4.2 its more than likely the EGR ports...Please list the engine..I may know what to tell you to fix it..

Sep 14, 2011 | Ford E-250 Cars & Trucks

1 Answer

Erg code 405 how do test it


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.

Jun 24, 2011 | Chevrolet S 10 Cars & Trucks

1 Answer

1998 chevy.s10 code 405


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.

Jun 24, 2011 | 1998 Chevrolet S-10 Pickup

1 Answer

Po401 ive cleaned the egr & replaced the egr but i keep getting this code??


depending on your model, there may be a solenoid valve that turns the vacuum to the egr valve on. If the solenoid fails, the egr valve will not open. Follow the vacuum line on the egr valve--does it go to a solenoid valve? If yes, apply 12 volts directly to the solenoid blades to see if it clicks open. If it doesn't click, replace the solenoid.

Apr 09, 2011 | Chevrolet Lumina Cars & Trucks

1 Answer

Check engine light on egr code


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. ---

Sep 24, 2010 | 2000 Mercury Cougar

1 Answer

I have a 99 Windstar 3.8L Keep getting DTC PO401 have replaced DPFE EGR Valve and EGR tube still keep getting Code PO401


Does the egr vavle open ? You will need to use a scanner to test the dpfe voltage when the egr valve is energized you should read around 3.5 4.00 volts. Also you could remove the vacume line from the egr valve and with the engine running you should see around 100 rpm drop in engine rpm at least this would indicate the egr valve is capable of flowing egr gases through the system to the cylinders.

May 30, 2010 | 1999 Ford Windstar

1 Answer

What component does engine code P1635B on a GM vehicle deal with?


Trouble Code: P1635

5-Volt Reference 'A' Circuit Malfunction
Possible Causes:


5v VREF circuit is shorted to sensor ground or chassis ground 5v VREF circuit, MAP or FTP sensor circuit is shorted to (B+) 5v VREF circuit shorted to EGR sensor High signal circuit EGR solenoid valve (and sensor) is damaged or has failed PCM has failed

Sep 03, 2009 | 2003 Pontiac Aztek

1 Answer

Turned car off at gas station want start back acts like missin


all of these problem codes refer to EGR valve and emission controls. It may be, if egr was fixed, it would be ok!! take off EGR valve and clean carbon from egr hole in engine and from EGR valve. if egr valve is bad or plugged with carbon then the car will act like it is not getting fuel, it will bog down.

Jan 07, 2009 | 1998 Chevrolet Malibu

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