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sean, UK Ford Master Technician
Category: UK Ford
Satisfied Customers: 3104
Experience:  Ford Master Tech since 2001 & MOT tester mechanic since 1984.
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Ford mondeo: hi, i have the check engine light on after i

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i have the check engine light on after i refill gas today

i did run the self check diagnostic test and have the following DTC codes:


what dose each of this codes means? are they related to the check engine light?


Hello, I hope I can offer you some assistance.

How did you obtain the codes? You say about the self check diagnostic, do you mean in the cluster?

Let me know and I'll reply as soon as I'm able to.

Thank you.

Customer: replied 4 years ago.

hi, thank you for your reply


that's right:


i obtain the codes from digital screen on my car "cluster", i access the test mode by holding "ok" on steering wheel and turn the key to position 2

self diagnosis starts and i find this DTC codes



Hello again,

it is a common misconception that the instrument cluster self test gives DTC's for the engine management system, it provides cluster related DTC's on test 10 of the cluster self test, DTC should be displayed above the code, these will be displayed at 1 second intervals, once you press OK again the cluster will scroll to the next test, the format of the codes shown in the cluster is designed for Ford engineering and can only be translated into usable codes by Ford IDS.

The only way to find out why the engine management light is on is to have a scan of the engine management control module carried out using an appropriate code reader, this will give you the standard EOBD codes for example a catalyst efficiency code would show P0420. If you want to do this on a DIY basis then cheap code readers are available on the internet for around £35, these code readers also reset the light after the fault has been fixed.

Let me know if I can assist any further or if you have more questions regarding this and I'll reply as soon as I'm able to.

Best wishes,


Customer: replied 4 years ago.

thanks a lot for your reply,

i will buy a code reader to discover this codes,

but today i recognize a serious problem after this engine light is on:


i did turn my car running the test mode again but scrolling to "engine temperature value"

the engine usually works normally under 95 C degree ,

but i noticed that (only) when i am driving idle or stopping for traffic light; engine temperature raises, it keep getting overheated unless i drive, or push accelerate pedal ??


the Temp. gauge doesn't show any change until the engine temp is above 110 C !! , that's why i am monitoring by cluster display.

see the picture from this link


so could you please tell me, on what parts should i check ?


please note that the fans are working fine, overheating only occur while stopping, there is no sign for water leak or Valve problems.




Hello again,

have you the chassis number of the car? This way I can check for any concerns known to Ford. When the car is overheating does the coolant boil? Or is it just the gauge is going into the red?

Let me know.

Thank you.

Customer: replied 4 years ago.

i don't know if it boil, how can i check ?

when i release the cap a little bit the water level rise above the MAX level (if that help) i don't know what kind of this coolant water but it color is red


i didn't release the cap until the engine cool down.






Hello again,

at the moment the Ford site is down so I will check against the chassis number later today when it comes back online, this should be around 14.00 UK time (not sure where you are SAU). If no coolant is coming out of the expansion tank cap when the gauge is reading 110 degrees then I suspect that this will be a calibration issue with the engine management control module.

You need to have the latest level software loaded into the PCM, this needs to be done using a suitable diagnostic tool for example Ford IDS. The light may well be on due to the PCM detecting an over heat condition even though the engine isn't actually over heating. I believe there was a message from Ford about this to dealers but until the Ford site comes back online I can't confirm this.

Have the software calibration level checked and updated and go from there, I'll reply later today when the Ford site is up if I find the broadcast message regarding this.

Let me know if I can assist further and I'll reply as soon as I'm able to.

Best wishes,


Hello again,

there is a revised thermostat for this engine, the Ford finis code is(NNN) NNN-NNNNso it would be a good idea to fit this along with the revised software level in the PCM.

Let me know if I can assist further and I'll reply as soon as I can but I'm unsure of the time difference between the UK and Saudi (the car was registered new in Saudi Arabia).

Best wishes,


Customer: replied 4 years ago.

Dear sean,


i think i found the problem , thank to you


when the engine start overheating again, i release the coolant cap

the coolant boil, and i found what it seems; a small crack from the tank

as it shown in this video:


the engine light goes off this morning.


so i hope once i fix the crack every thing will get back to normal


best regards


Hello again,

hopefully that may be the concern, but remember that when the engine is hot and you release the expansion tank cap the coolant will boil as you've dropped the pressure in the system.

Let me know if I can assist further.

Thank you.

Customer: replied 4 years ago.

yes thanks a lot,


one last question regarding this please,

from the video above and from your knowledge, is this a crack?

or the tank are equipped with a hole to leak over filled coolant,

because what i see; a hole that is very perfect shaped to be a crack!!


thanks for you answers



Hello again,

it appears from the video that this is the hole for coolant to flow out of if the expansion tank cap releases the pressure if it exceeds the preset limit. The cap may have a number on it that indicates the pressure at which the cap will allow pressure to release, from memory I think it's around 0.5 bar or 7 to 8 PSI.

If when the engine is running as normal no coolant is coming out this way then I wouldn't worry about this, I would go back to my original suggestions.

Let me know if I can help any further.

Best regards,


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