I have a 5.0 Litre in my 96 Explorer AWD. The "Check Engine" light comes on and off intermitently while driving. No rough running or driveability problems. A guy at Autozone pulled the code with an OBD II analyzer and the code read "402". According to the SAE code list, this is "EGR Flow Excessive". I can understand a low flow condition from carbon, but what malfunction would generate a high flow condition? Have I read the correct fault for code "402"? Any thoughts on this subject would be appreciated.

 

Hi. I just checked my notes on engine codes and I don't have one for 402. That doesn'tmean there isn't one there though. If it is an excessive egr flow it may be carbon in the valve causing the vale to not close properly an will cause a crappy idle as well. The valves are not hard to clean either. Also try pulling the vacuum hose off and see if it makes a diference in the idle quality. There shouldn't be any vacuum at idle. If there is it is the evr solinoid that controls the vacuum to the egr. Mine was full of dirt. They can be serviced by carefully taking them apart and cleaning the filter and the rubbercoated disk in the bottom. This is where my problem was. The egr valve when taken off should be sealed. If you can blow through it, it is carboned up and needs to be cleaned. I used brake cleaner on mine(all I had at the time) and that did the trick. Also the idle valve on the side of the throttle body gets carboned up too and can be cleaned by removing and spraying with carb/choke, F.I. cleaner, or brake cleaner. Don't spray brake cleaner on the throttle body itself (there is a special coating on the throttle bore) and never spray any type of cleaners into a running engine as it will toast the 02 sensor. Hope this is of some help.

 

Thanks. The SAE code list for OBD II lists code 402 as "EGR Flow Excessive". The Chiltons "Manual" lists 402 as "EGR Flow at Idle". A leaky valve or solenoid makes sense. The idle quality is still good, however. I had an EGR valve leak on a Mopar and the engine would not idle at all. Just a magnitude of "how bad is bad", I guess.

Thanks for the tips. I'll try to soak the valve and check the solenoid for leaks.

 

The code P0402 refers to excessive EGR gases flow. One of the most common things that happens on our Police Crown Vics, is the EGR regulator filter gets dirty. Follow the EGR valve vacumn hose, to the regulator(has two vacumn hoses and a wire connector attached). There is a small round cap, about the size of a half dollar, it pops off and under the cap is a peice of foam, this is what needs to be cleaned. The "filter gets clogged and won't release the vacumn from the EGR so it keeps the EGR valve engaged longer than it should be. Clean it out, doesn't cost a dime. But you'll need to have the codes cleared by someone with a scanner.

Doug

 

He can also disconnect the battery for 10 minutes to clear the code. His engine will need to relearn its idle and operating parameters but it is much more convenient than trying to find someone with a scanner to clear the codes. The advantage to using a scanner is it doesn't erase the operating parameters. If the problem is stil there after clearing the codes, the light will come back on regardless of whether or not he uses a scanner or disconnects the battery.

 

If I am correct, the EGR regulator folter is under a plastic cap that rotates freely when turned. It is a @#$% to pop off as there are a number of tabs that have to be disengaged. Any particular trick to this?