Hi, last week I purchased a 2006 "06" Mondeo TDCI 130 bhp euro 4 which had done 163000 miles. To be fair the car drives fine and the gearbox is spot on. So far I have been averaging 55 mpg. I bought it cheap (£850) because the engine light was illuminated. Apparently it has been like it for two years but the previous owner did not repair it as the car was driving fine. It has two error codes P0401 and P0405 which both relate to the EGR. The EGR was not blanked. The easiest thing to do was clear the codes but they came back within 20-30 miles. I then replaced the EGR valve but again they came back within 20-30 miles. My understanding (which is not great) is that the code P0405 (flow sensor A circuit low input) could relate to the wiring of the EGR valve and the P0401 relates to the flow through the valve is insufficient. There does not appear to be any blockages in or around the EGR valve preventing flow. I have the 3 wire EGR valve. I disconnected and checked the current at the 3 pin plug with the ignition on. One wire (blue/white) was showing 6 volt, the middle one zero and the other one was showing around 10 to 11 volts.

Do these figures look right?

If not, could the faulty current/signal be causing the P0401 error code?

Although the car drives fine it just annoys me having the engine light illuminated all the time.

Regards, Lee.

Hello and welcome to the forum!

The symptoms appear similar to having a blanked EGR valve on a Euro4 mk3 Mondeo

If you have replaced the EGR valve there is not very much more you can do to fix it (if its the ECU it could be a very expensive fix)

And as the engine is running fine (if the EGR valve is not opening/ working - better than fine)

Then on balance you are probably better leaving it well alone

Or perhaps fit a solid EGR blanking plate as a precaution (in case the valve leaks ) cost = approx £5

The EML (engine management light) is annoying but is just a light - the new MOT will fail a car with an EML on (not sure if its advisory or compulsary, or when it comes into force etc) - but its only relevant on the day of the test - so keep the code reader handy, if you know what i mean

If its the ECU it could cost £1000+ to replace, recode the injectors/ turbo actuator to the ECU , not sure if the ECU and body control unit is in the same module , if so you may have to change the locks etc as well (this is all from the "top of my head"- would need to be researched in detail) - see why the last owner just left it?

Thanks for the comprehensive reply. If it is electrical/ECU issue I will definately leave well alone and delete the codes just before the MOT!

However, somebody has suggested it may be the vacuum solenoid/regulator which attaches to the EGR via a small pipe. I'm not really technically minded but I presume the simplest test will be to check my regulator/solenoid to see if I have suction when I remove the pipe from the EGR valve with the engine running? Thanks, Lee.

As above, get it blanked to make sure, then if your not having any problems, just ignore the EML until testing day. I think it has become part of the test now, but if thats the case, ,eople tend to use a code reader just before it goes in for testing to erase the fault. It is unlikely to come on whilst in the test then, so you should pass on that with no problems.

I went out this morning to test the vacuum hose into the EGR valve. I have a black vacuum solenoid with a white top. There is a two wire plug which goes to it and there are three hoses which leave it. The first one marked "in" goes to the brake vacuum which I presume supplies the vacuum to the solenoid. The second one marked "out" goes to the EGR and the third one is the largest hose and this should go into the top of the air filter box. However, mine was just hanging loose in the engine bay. I have now connected it to the air filter box (I was hoping this would solve my issue but after clearing the codes again the P0405 came back as a pending within a few minutes). The large hose to the air filter box has a lot of suction on it. When I put my finger over it it really applies some suction. When I block this hose fully the car stalls and beeps, is this normal? The hose to the EGR has very little suction (it has some but nowhere near as much as the other hose). This was with the car idling and getting warm but not fully operating temperature. Should I run the test again when the engine is hot after a long journey? Does this make any sense to anybody. Any help would be appreciated. Lee.

Okay, I drove 10 miles to work. Engine was up to normal operating temperature. With the engine running I reset the fault codes and then disconnected the hose from the vacuum to the EGR. There was hardly any suction or vacuum created at all. Maybe enough to hold onto a very small piece of toilet tissue but nowehere near enough to hold onto my A4 folded piece of paper. Out of interest the other pipe to the air filter housing was again really powerful suction and held onto the piece of paper easily. I'm thinking the vacuum solenoid is knackered not allowing sufficient suction go to the EGR. I will try to get another one from a scrap yard. Does it have to come from a diesel or would any identical one suffice? Lee.

To be honest the EGR on the ford mondeos are silly because you could fix all the problems and it still would clog up! It's a really bad design. I would suggest just getting rid all together your engine will run a lot better of fresh air not re-cycled air! Pluss less carbon out of the exhaust