Service engine soon light.


Asked by Mar 07, 2016 at 10:39 AM about the 2003 Ford Mustang Base

Question type: Maintenance & Repair

My 03 mustang has been a problem since day one,
after 1 month, the engine cooling sensor has been
replaced treat has also been replaced along with
the fan because it over heated on us. So after a
couple of months I noticed the temperature was
reading right I would drive 9 miles and temperature
stayed at cool. So my husband change  fuel filter
and also did a oil change on it. He left the car idling
and it over heated again. He took it auto zone and
they did dig test and it was the cooling engine
sensor agian, we changed that just 3days ago. So I
had my a/c on and car was idling parked and it
over heated agian and now service engine soon
light Is on... please help

6 Answers

Tom Demyan

The sensor is probably tripping the CEL due to the high temperature, You have to figure why it is overheating in the first place. Low coolant level, stuck closed thermostat, fan not coming on, etc.


It defently sounds like you have cooling system issues, the cooling fan should turn on when the A/C is turned on, if it does and you still overheat then the most common cause is a radiator restriction, and that requires a radiator replacement. If the A/C is not on then the fan normally kicks in at around 200 to 220 degrees, depending on ECM settings, if it doesn't then there maybe a wiring or relay problem. This is assuming the thermostat is operating properly. HTH


The fan has been replaced less then a year ago. I did put coolant in it. So what do you recommend me to do about engine light on.. I will be replacing fan and going to get a radiator flush...


If it overheats wen idling and a/c on, typically its either fans not cooling it fast enough or radiator plugged. Wen u drive moderate speeds the cool air will help cool it, but not at idle. There u need fans to kick on and off as temps rise. Since u replaced fans, etc and assuming antifreeze is filled and there are no other issues I would guess restricted radiator. Can try flushing it, but I don't think they"re worth the hassle, they to me only buy a little time. Look at rock for maybe good price


I wouldn't even bother with a flush at this point in time, that is usually just a maintence procedure not meant to cure already existing cooling trouble, just replace the radiator. As far as the check engine light, you need to find out what it is telling you so a code check is the next step on that end, write them down and repost them back here and someone will jump in and help you out with further diagnosis. HTH


Also did or husband mix antifreeze? They are not all compatible with each other, they can gel! Make sure no gelling has occurred and use right antifreeze!

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