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Robert, Ford Technician
Category: Ford
Satisfied Customers: 5390
Experience:  Fully qualified 19+yrs exp/self employed technician in the UK
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Engine warning light is on constantly. Sometimes it turns

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Engine warning light is on constantly. Sometimes it turns off for a few hours, then comes back on. The car is working as normal, and have no symptoms and not other warning lights on. It's a Ford s-max 2007. I see error code c41668 in the self diagnostics in the car info screen. I saw in one forum that it was suggested that it might be a defect sensor or something. What can I do here? Any easy fix sensor to replace first before I do anything more serious?
JA: Just to clarify, what are the exact lights you're talking about?
Customer: Yellow engine malfunction warning light
JA: What is the model of your '07 Ford?
Customer: s-max
JA: Are you fixing your vehicle yourself? What have you tried so far?
Customer: Have not tried anything
JA: Anything else you want the Mechanic to know before I connect you?
Customer: no
Customer: replied 7 days ago.
It might of course be that the codes I found is not related to the engine malfunction warning light.


You should never rely on self test codes in my opinion.. the proper way is to get it plugged into a decent scanner and do a complete test on the car and see what other codes are listed and in what modules,that way you'll get clearer idea what might be going imagine there wont be just that one stored as sometimes that code can flag up at the same time as other codes stored or fault elsewhere.. C41668 is network communication error. means there is communication problem regarding the Vehicle Dynamics Control Module/which is essentially run via ABS module...

Customer: replied 1 day ago.
Hi again…I finally managed to get a scanner and read code. I did an automatic scan, and detected a remark on PCM-Powertrain Control module. When I “enter” on this remark, then the following code shows up: P0490:00E. Control circuit highI deleted the code, and the engine warning light disappeared. I am not sure for how long. First time it came back after short time. But now it’s been OK since yesterday.Is it anything I can try to do here to fix the error?

Hi..there..thanks for getting back to me..

Well you see thats why you should never rely on dashboard self tests..because that code you scanned now suggests P0490 Exhaust Gas Recirculation "A" Control Circuit High

That means your EGR is either blocked or the electric solenoid that controls the valve within the EGR is either not being commanded to open or close properly maybe due to seizure of the valve blocked with soot and thus creates a high draw in voltage and sets a code..if the code hasnt come back then give the car good run or try adding some catalytic converter additive to the fuel tank and see if that helps. other then that on them diesels engine dependng which version you replace the EGR means having to renew the entie manifold that egr is bolted not an easy job on them cars im afraid.being situated quite far down at the rear of the engine...

Customer: replied 1 day ago.
Thanks for quick reply. The engine version is S-MAX (WA6) QYWA 1.8 TDCI, 125 HK. I will try to add some catalytic converter additve to the fuel tank. Maybe it's possible to try to clean the valve? But I do not want to dismantle the entire manifold.. But it looks like parts of the unit can be dismantled for checking? Some forums discuss that the egr can be blinded... But I am not sure how smart that is.... And in Norway it's anyways not legal...

Well in sense you can sort of clean it out in situ.but you still need to dismantle it like for example remove the actuator (as per picture) 4 philips screws one is quite hard to get to down the back lower side - /intake tube, the exhaust gas supply tube..this is the metal ribbed one that comes up from the egr cooler..and all wiring across the get enough room you'll need to remove the wipers and the plastic trim that runs along the back..its is possible to remove it from the i say its quite ackward with getting to the you need something at least clean it out is very dirt job to carry be prepared if your going down that route.. I mean the usual procedure on them is the entire manifold off to clean or replace..once you get the room down the back it pretty straght forward..

Also check the plug connector to the egr solinoid..check it fully connected and check the pins for corrosion..spray some contact cleaner into the pins....

"Blanking" the EGR is just masking the problem really..your essentially blank with solid metal plate that metal ribbed tube that carries the exhaust gas that comes up from the cooler and place the blanking plate between that and the egr body/manifold..sometimes that can work on some engines..other times it will just flag a code unless you get it mapped out from the ecu..Yes alot of countries including the UK are now alot tighter on modifications that control emissions or increases them..

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