Hi guys I keep getting a code 9 on my 91 Protege LX and that says it is the coolant temp sensor in my manual. So I checked it the way they explain and it checks out ok. When I check the other coolant sensor in the thermostat housing it checks bad, could that be the one that throws the code? I also don't think my fan kicks on and I checked it through the diagnostic port and it worked fine but I never hear it or see it kick on. My temp guage stays right about in the middle all the time when running but when the engine gets warmed up usually when it is hot out it will develop a erratic idle and sputter at first when you up shift kind of like it isn't getting any fuel but run out fine after the little stumble. Then it may go away and may not do it for a while then come back or keep doing it. It does not seem to do this when it is cooler at night and doesn't do it until the motor warms up. I don't care to change some things but at $20 bucks or more a pop for all these sensors it could get expensive pretty quick. It seems like it may be overheating a little but by my guage it doesn't seem to be. I also read that somehow the temp sensor effects the fuel injection somehow. Sorry so long winded but this problem is driving me crazy. Thanks for any help.
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code 9 is the coolant temp sensor. Has nothing to do with your fan coming on or off, like jturbo said, check your fan relay and your thermostat. Assides from that, just by-pass your relay and hook up a switch for the fan so you can set i.
Don't forget to unhook your battery when you change out your sensor, sometimes your ECU won't notice the change.
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So should I replace the coolant temp sensor even though it checks out ok. I tested it for resistance both hot and cold and it checked out ok according to my manual. What does the temp sensor (switch) that is in the thermostat housing do? Would it have anything to do with fan? It does check bad.
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Originally posted by gd71 View PostSo should I replace the coolant temp sensor even though it checks out ok. I tested it for resistance both hot and cold and it checked out ok according to my manual. What does the temp sensor (switch) that is in the thermostat housing do? Would it have anything to do with fan? It does check bad.1993 Protege LX-Midnight's shadow SOLD
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2010 VW routon
Originally posted by jay.....they totally underestimated the number of gearheads such as myself that have families but refuse to grow the hell up and stop playing with cars, or that otherwise see the utility of having 4 doors. Obviously I ain't alone, as there are a helluva lotta sti and evo here. Bueler? Beuler? Mazda? Mazda?
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Well I ended up changing all three sensors and it is now running fine and the fans are kicking on. No more code 9 either. The only problem now is the idle likes to fluctuate from about 250 to 900 rpm's sometimes but not always. I am going to try to clean the throttle body and check for vac leaks. Thanks for all your help.
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