I changed EGR valve twice and the engine light still comes on.When scanned the reading you get is insufficent air flow.I tried changing air filter and flushing air intake system but it still didn't help.Do you have any suggestion for me that might help to fix this?
- If you need clarification, ask it in the comment box above.
- Better answers use proper spelling and grammar.
- Provide details, support with references or personal experience.
Tell us some more! Your answer needs to include more details to help people.You can't post answers that contain an email address.Please enter a valid email address.The email address entered is already associated to an account.Login to postPlease use English characters only.
Tip: The max point reward for answering a question is 15.
The P0401 is an insufficient flow code and is almost always caused by the DPFE sensor. This sensor measures the back pressure in the exhaust as is a more accurate way of determining EGR flow than the old EGR position sensors. When the EGR valve opens the exhaust back pressure changes and the DPFE sensor informs the processor of this information. If the sensor isn't reading a change when the EGR valve is turned on through the solenoid, it will throuw a p0401 code. The only true way to check this is to install a scan tool and measure the DPFE voltage. Normal DPFE voltage is approx. .9 volts at idle.
The DPFE sensor dealer part price is approx. $140 but you will find cheaper prices at an aftermarket parts store. Good luck.
The code P0401 is often not a problem with the EGR valve itself. Rather, the EGR system is not allowing enough EGR to flow back into the combustion process to sufficiently cool the peak firing temperatures. Once the code P401 has been retrieved with a scan tool, the freeze frame data should be documented and analyzed in order to determine what engine conditions were present when the code was triggered. It is recommended that the vehicle be driven in such a way as to duplicate the code setting conditions with a data streaming scan tool connected, so the behavior of the EGR actuating components and feedback sensors can be monitored. Common Tests to Determine Whether the Problem Is an EGR Control Problem, a Plugged or Restricted System, or a Defective Feedback Device
Does the engine die, not just stumble, when the EGR valve is manually raised to its maximum? (Use either a vacuum pump or bi-directional scan tool if it's a digital EGR valve.)
Is the EGR valve getting sufficient vacuum? (Use the manufacturer EGR vacuum spec.)
Is the EGR system restricted? (The engine stumbles, but does not die.)
Is the EGR system plugged? (Engine RPM does not change.)
Does the EGR valve work?
Raise the RPM to 3000 and check manifold vacuum. Then open the EGR valve to its maximum-the manifold vacuum should drop by at least 3" of mercury. If it does not, there is a flow and/or restriction problem.
Test the EGR temperature sensor (if equipped) with a propane torch and a DVOM.
Test the accuracy of the EGR valve position sensor with a scan tool or DVOM by raising or lowering the EGR valve.
Test the Digital EGR Pressure Feedback Sensor (DPFE) with a data streaming scan tool to verify that the voltage or lift percentage changes according to spec.
Verify that the front Oxygen Sensor readings drop and the Short Term Fuel Trim increases when the EGR valve opens. (EGR leans out the mixture.)
ok here the problem! you replaced the egr for no reason !the problem is all the carbon build up in the intake manifold just under the egr valve! this happens the alot of gm s !to solve the problem intake must b removed and clean out !!! remove all the carbon from the egr port!
what dtc do you have? is it p1401? if so the description is for insufficent air flow egr circuit. this is typicaly caused by a faulty DPFE sensor (delta pressure feedback emission) it is about the size of a buisness card and about 1/2" thick. its black and has a small wiring connector and 2 thick vaccum hoses hoing to it. Fords first step for repair for this DTC is to replace dpfe sensor and to assure hoses are not ruptured. i STRONGLY SUGGEST to use only factory sensors as it is often i replace new aftermarket ones that done work right from the start. this part is relatively inexpensive....good luck!