I have a 2008 Ford Escape Limited with about 110,000 miles on it.

Recently, the CEL turned on so I scanned for a code and got P402, Insufficient EGR flow. I figured the EGR valve must be stuck, so I removed it and cleaned it, and verified that it would move freely.

Now I just get a P403 code, Exhaust Gas Recirculation Circuit Malfunction.

Not sure what else I need to check. Does anyone have any ideas?

I appreciate the help! I hate having to take a vehicle into the shop when I can just DIY.

 

I *think* you can get the second code if you turned on the system with the EGR unplugged. It *knows* how far the valve is open by a variable resistor modifying signal voltage. If plugged in, and commanded to X, the resistance would cause a specific voltage reading, but didn't. That is how it got the 1st code, I think. The second code would be for a disconnected or electrically inoperative EGR valve, where the result is either zero or way off. Translated, the 1st says it moved, but not to where it was expected, the second says there's nothing out there to move... sort of. I think.
tom

 

I looked at the valve and there are no electronics in it or wires, just a vacuum tube, the exhaust tube, and the tube going to the intake manifold. There is a solenoid connected inline with the vacuum tube line, and a sensor connected to the exhaust tube. Could it be one of them?

 

You're right, I just went and looked. There is a gizmo connected or teed into the vacuum line, directly behind the EGR valve. It senses the vacuum applied to the diaphragm. I think some have a sensor that compares vacuum to exhaust gas back pressure. It can give false readings when it gets carboned up, and set the code for inadequate flow. Dang, I was right. DPFE noted below.

I searched a bit and came up with:
A code P0402 most likely means one or more of the following has happened:

* The DPFE (differential pressure) sensor is faulty and needs to be replaced
* There is a blockage in the EGR (most likely carbon buildup)
* The EGR valve is faulty
* The EGR valve may not be opening due to a lack of vaccuum

Possible Solutions
With a P0402, it is common for people to replace the EGR valve, only to have the problem return. The most likely solution is to replace the DPFE sensor.

* Check the voltage at the DPFE sensor both at idle and when the EGR is open
* Replace the DPFE sensor

P0403
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

Possible Solutions

With the ignition on and engine off, use a scan tool to activate the EGR solenoid. Listen or feel for a clicking, indicating that the solenoid is operating.

If the solenoid does operate, you'll have to check current draw on the ground circuit. It should be less than one amp. If it is then the problem is intermittent. If it isn't then there is excessive resistance in the circuit and perform the following

1. When it's activated see if you can blow lightly through it. IF you can\'t there may be a blockage causing excessive resistance. Replace EGR solenoid as needed. If there is no blockage, disconnect the EGR solenoid and the PCM connector containing the EGR solenoid control circuit. Using a digital Volt-Ohm meter (DVOM) check resistence between the control circuit and battery ground. It should be infinite. If it isn't, then there is a short to ground on the control circuit. Repair the short to ground and retest as needed.

2. If the solenoid doesn't click as it should, disconnect the EGR solenoid connector and connect a test light between the two wires. Using the scan tool, command the EGR solenoid on. The light should light up. If it does, replace the EGR solenoid. If it does not perform the following: a. Check for 12 Volts on the ignition supply voltage to the solenoid. If it isn't present, inspect the supply circuit for an open, or a short due to chafing or breakage and re-test. b. If it still doesn't operate: then manually ground the EGR solenoid control circuit. The light should light. If it does, repair open in EGR solenoid control circuit and re-test. If it doesn't, replace EGR solenoid.

Go here, the source of some of the verbiage: http://www.obd-codes.com/

 

I remember working on the EGR system on my '97 Ranger. I had to use a hand vacuum pump and measured voltage somewhere.

Ended to be the EGR valve itself. The fitting to the EGR wouldn't come loose. I even purchased a flare nut wrench, took it to work, had it heated to bend to clear the dome on the EGR valve. Tried all kinds of solvents, heat, etc. but nothing worked. Had two thirds of the nut cut with a Dremel and still wouldn't budge. I had the wheel off and wheel well cover off too. Gave up and decided to replace the EGR tube but it was froze in the exhaust manifold. Out came the SawsAll!!