2000 mitsubishi montero sport, engine light is on code 403. I replace the egr, but engine light still on. What ma be the problem?

code p0400 refers to exhaust gas recirculation (EGR) system--flow malfunction===causes--hoseleak/blockage, basic setting not carried out (if applicable)--wiring---EGR valve--EGR solenoid---ECM
As the EGR unit is susceptepable to corrosion. Check it out or replace it

Code 400 is for a problem with the EGR valve gas flow or the flow sensor.

Trouble Code: P0403

EGR Control Circuit Malfunction
Possible Causes:


EGR solenoid control circuit is open or shorted to ground . EGR solenoid power circuit is open (check power from relay) . EGR solenoid is damaged or has failed . PCM has failed .

Your new EGR valve (assuming it wasn't defective out of the box), is fine, but the car's computer just needs to have its code 403 cleared. Even though you've corrected the problem, the computer will still light the "Check Engine" light, and store code 403 until the code is cleared using an OBD-II (On-Board Diagnostics 2) code scanner.
Note that the car will function perfectly with its new EGR valve, a lit "Check Engine" light and a code 403 stored. Its just a good idea to clear the code, so that then only NEW problems will become the reason that the "Check Engine" light gets lit.

code P0403 EGR ( exhaust gas recirculation ) valve solenoid malfunction, could be many things most likely would be just a bad control solenoid but could be the wiring to the solenoid, but most likely is not a bad EGR valve.

Use a vacuum pump to operate the EGR, at idle. If it stalls out then the egr valve is fine. If there is a vacuum leak then you found a problem in the EGR Valve diaphragm in that it is leaking air (not hold vacuum).

If there is an electrical problem with the EGR Valve Solenoid, then it will be picked up by the computer.

Good luck on this repair.

get the code so you know what system is causing this

The Cat code could have cleared itself if the computer doesn't detect a problem anymore. Fix the EGR problem as it is still active.

its an egr CIRCUIT MALFUNCTION which means can be any type of problem with the whole circuit -- wiring --connections fuses relays etc not just the egr valve more than likely the valve was good need to check and test the whole egr system

when your vehical throws a code and you replace the defective part, you must clear the code or the ecm will still recognize it as an active code.