02 Trooper Check Engine Light Code indicates EGR valve, EGR valve replaced, BG Carbon chemical flush, Seals replaced to assist with vaccum, battery terminal disconnected, check engine light continues to come on. Please Help

you are right posible bad egr valve or you have carbon bild in the egr system and when came loose block the seat at the egr valve seat instal new egr valve with speciar gasket with screen an posible you save a lot

Its either a faulty EGR valve or it has carbon build up inside.Take valve off and clean carbon out using a non-chrlonated brake cleaner and wire brush.

The EGR Valve and System - it's just three letters, but EGR can result in AGGravation.

Common in automobile emission systems since the early 1970s, the EGR (Exhaust Gas Recirculation) valve controls an engine's emission of smog-causing nitrous oxides, or NOx. Its job is to route a portion of the exhaust gases back into the intake manifold. That lowers combustion temperature to below 2,500 degrees Fahrenheit - the temperature at which NOx gases form.

EGR flow is controlled by the engine's computer, which opens or closes the valve as needed. The EGR system is, for the most part, in the "out of sight, out of mind" category, and typical doesn't require regular maintenance. But if it gets clogged with carbon deposits, you'll see your "check engine" light come on, and a code (perhaps P0401 or P0402 or P0403) will show that there is insufficient flow. That typically results from a vehicle being driven persistently on short trips that don't allow the engine to fully warm up. Flow problems also can be caused by carbon buildup due to failure to change the oil frequently enough.

A clogged EGR valve not only results in higher emissions, it can affect fuel economy and cause rough idling - even serious engine damage. Valves can usually be cleaned, but replacement is often recommended.

A code P0401 most likely means one or more of the following has happened:
* The DPFE (differential pressure feedback EGR) sensor is faulty and needs to be replaced
* There is a blockage in the EGR (tube), most likely carbon buildup
* The EGR valve is faulty
* The EGR valve may not be opening due to a lack of vaccuum

Possible Solutions: In fixing this code, it is quite common for people to just replace the EGR valve only to have the OBD code return. The EGR valve is not always the culprit.
* Use a vacuum pump and pull the EGR valve open while monitoring engine RPM's & DPFE voltage. There should be a noticable difference in RPM's with the EGR open
* Clean out the EGR valve and/or tubing to remove deposits
* Check the voltage at the DPFE, compare to specified values (refer to a repair manual for your specific model)
* Replace the DPFE sensor (with a good quality / OEM one)
* Replace the EGR valve

p0401 is an insufficient EGR flow. check your vaccum line that is connected to the egr valve to see if it is cracked. then start the car and unhook the vaccum line and it should have suction similar to a vaccum. If that is good then you need to take your EGR valve off and look up inside of it and make sure it is not clogged up. Also look where the valve connects to the engine and make sure the hole there is not clogged up with carbon. If that is all clean then your egr valve is bad

1. po401 refers to an insuffient flow of EGR gasses
2. locate egr valve
3. with engine running at idle
4. on the underside of the valve you can access the diaphram.
5. wearing glove if ness
6. lift diaphram while idling
7. does engine stall or run very rough?
8. if not remove valve
9. start engine
10. you should hear a very large vaccum leak and exhaust noise
11. if either are missing investigate cause
12. if ok reassemble.
13. locate DPFE sensor
14. inspect sensor for damage
15. inspect hose to sensor for damage
16. replace sensor

P0401: Isufficient Flow Detected in EGR system.
-clean the EGR port with the carburetor cleaner.
-clean the EGR passage inside the EGR valve with the caburetor cleaner.
Reset the light, if the light still coming back, then replace the EGR valve.

Everyone says to test out your DPFE sensor. This controls the flow of the egr. When the codes pull up, everyone thinks its the egr, but really its this little guy.
Take it by a shop and see if they can mess with the bugger. They usually run about $50+.

I have a 2000 Isuzu Trooper that had a PO401 code that would reset and then 2 miles later the light was on again - I found if you remove the EGR valve and start the engine that the engine should idle rough - If it doesnt and you have vacumn at the intake port spray carb cleaner down the port slowly and see how long it takes for the engine to run rough - Keep spraying till the engine dies and spray some more down the passage and let the engine set for 5 minutes and then restart the engine - it will run rough at first but clear out - you should be able to feel the engine RPM change when you put your finger over the intake vaccumn port for the egr - If not then repeat the cleaning method again - If you do feel the rpm change then put the egr valve back on and clear the code and run your drive cycle to see if it is fixed.

check inside the egr port on the intake for carbon build up.if so clean it out with a piece clothes wire.then vacuum up debri with shop vac.

The Egr ports are plugged in the intake. Remove the throttle body elbow behind the throttle body, and clean out the carbon. I can walk you through it if you need me too. This is common on the 4.6