answersLogoWhite

0


Best Answer

Check the EGR selenoid valve. The vacuum will pass throught the defective selenoid valve and go the EGR valve even if it has not been activated. The ECM will not detect a defective selenoid valve - only an EGR problem.

DPFE sensorIf it's a Ford product, you may need a DPFE sensor. You should also check for a restriction in the EGR passageway.
User Avatar

Wiki User

8y ago
This answer is:
User Avatar

Add your answer:

Earn +20 pts
Q: What can you check or replace if the check engine light comes back on and the code is P401 and you have already replaced the EGR valve?
Write your answer...
Submit
Still have questions?
magnify glass
imp
Related questions

How do you replace the check engine light bulb in the dashboard on a 1994 Toyota Camry you know the bulb needs to be replaced and its not a fuse bc all the other ones work just the check engine light?

To replace the check engine light bulb, you will need to remove the dashboard. Once you have removed the dashboard, the bulb for the light will be exposed and can be changed.


Why wont the new starter you replaced on your 93 ford ranger 4 cylinder disengage after starting engine?

Check and or replace your starter solenoid.


How do you replace a bulb located in the rear of a 1999 Lexus gS300?

2006 Lexus gs300 awd check engine on after spark plugs replaced


Engine check light comes on and computer reads knock sensor?

You need to test/replace the knock sensor. ireplaced it already.


You have replaced the O2 sensors in your 1998 Mercury Mystique how do you reset the check engine light w no diagnostic scanner?

I have a 98 mystique, and when the check engine light comes on, I simply disconnect the positive battery terminal for a couple of minutes. When I replace it, the check engine light is cleared. It resets the computer.


How often a PCV valve should be replaced in a 2000nissan altima?

replace only when u get a check engine light. the valve is good for the life of the motor(should be)


How to replace Nox sensor on 2003 Chevrolet 5.3 engine?

There are 2 knock sensor on the 5.3L engine. And they are under the intake manifold. To get to them you will have to remove the whole top of the engine- INTAKE MANIFOLD. Why do you think they need replaced???? check engine light came on for 2 sensor


What could cause the Check Engine light to come on already replaced the gas cap and the light went off for a couple of days now is back on again?

There are pages and pages of things that can cause a check engine light. You need to have it checked with a scantool. Then the code can be diagnosed and repaired.


What does the pedal relay mean when you check engine light comes on?

It means that your relay is out, and has to be replaced with a new one, and once its been replaced, your check engine light will turn off in about 20 minutes or so.


Reset check engine?

check engine light reset on a 1999 Acura CL 3.0.. Just replaced the egr valve. Thx


Should you do 60000 mile maintenance for your 1998 Toyota Camry?

Yes, you have to. Engine oil, engine filter, transmission fluid, transmission filter, differential fluid, coolant have to be replaced. Also you need to check all hoses. Rotate tires, check battery. Make alignment. Probably replace sparks and spark wires. Check brake fluid and stirring fluid. Replace air filter.


What can you do if your lights won't turn on and you've already replaced the light switch?

Did you check the fuse?