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EricFromCT, ASE Certified Technician
Category: UK Car
Satisfied Customers: 3809
Experience:  ASE Master certified L1, L2, Diesel Certified 16 years experience
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A P0404 error - have tried 2 replacement EGR valves (both

Customer Question

A P0404 error - have tried 2 replacement EGR valves (both used) and cleaned everything out. Don't know where to go next. I am not an expert - a mechanic has done it for me
JA: Sometimes things that you think will be really complicated end up being easy to fix with a Nissan. The Nissan Mechanic I'm going to connect you with knows all the tricks and shortcuts. Tell me a bit more about what's going on so he can help you best. Are you hoping to fix this yourself?
Customer: no, my neighbour is a professional, but he has run out of ideas
JA: OK! The Nissan Mechanic will help you with the diagnostics so you are sure to get this fixed right. Is there anything else important you think the Nissan Mechanic should know about your Nissan?
Customer: X Trail Diesel 2.2 L 2004
JA: OK. Got it. Last thing - JustAnswer charges a fee (generally around $18) to post your type of question (you only pay if satisfied). While you're filling out that form, I'll tell the Nissan Mechanic about your situation and then connect you two.
Submitted: 1 year ago.
Category: UK Car
Expert:  EricFromCT replied 1 year ago.

Hi. Please have your mechanic check the egr cooler. They can plug up and cause lack of egr flow and set p0404. Is this something he will do for you?

Customer: replied 1 year ago.
EricYou say they can "plug up"? I am not sure what you mean here, do mean they can get blocked? I know he has cleaned out anything he can, but I will ask him if he has looked at the cooler. He did say he could do with a wiring diagram to enable him to check the valves are opening and shutting properly and to rule out electrical problems. He has spent a lot of time on it already, so is a bit reluctant to spend too much more time, but interestingly the car is performing better than ever, with tremendous acceleration.
Expert:  EricFromCT replied 1 year ago.

What I mean by plugging up is that the exhaust gasses that run through the EGR cooler can collect soot on the fins of the cooler and actually restrict the egr flow. Setting p0404. Unfortunately I do not have the diagrams for the X-Trail. Also if there was an electrical problem with a valve or the wiring a circuit code would be being set in the computer.

Customer: replied 1 year ago.
Thanks for explaining clearly - I will see if he has checked that.
Expert:  EricFromCT replied 1 year ago.

Your welcome. Thank you and please rate my service and let me know what your mechanic says. Thank you.

Customer: replied 1 year ago.
My mechanic says had cleaned out everything he can including the cooler. I am getting him a workshop book so he can see the wring diagram and check that the EGR valve is opening and closing. Since we have tried 3 EGR valves, we wonder if perhaps the connector is poor or something along those lines. The problem happened after he put a new clutch in and to do so he disconnected the EGR, and re-connected afterwards.