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2002 Chevrolet Impala

Question: OBD Code P0118

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Ditto, 3.4L V6, Compton, CA, April 23, 2011, 01:11
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 Rookie

Originally I had taken my car to have the radiator fan assembly changed as I notice the car would heat up when driving on street and would cool completely down on highway...Well I had it replaced and then got OBD codes P0117 and P0118 so the ECT sensor was replaced and code P0117 disappeared, but P0118 is still there and the ECT sensor needs to be disconnected in order for the fans to turn on, but they stay on all the time while the car is on. The mechanic told me the PCM was damaged, but I'm a little skeptical, I've had the PCM replaced when my car would just shut down in the middle of my drive wherever I was and this time it seems to running good. So I'm curious to know if the PCM is really damaged or this is just his way to temporarily fix the problem? If I connect the new ECT sensor the fans completely stop working unless I am driving on highway, If the sensor is umplugged the fans stay on until the car is shut off ( I also replaced the fan relays) I was also wondering if a clogged radiator may be causing this issue? Any suggestions???

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  • Answer #1

    cogcan April 23, 2011, 05:07
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     Journeyman

    you say the fans come on driving down the hwy ,how do u know that, if its cause it cools down, thats probably cause your moving air through radiator, not fans being on.i gotta think about this one for a while.
    p0118 NOTE: Usually, P0118 is indicative of a bad temperature sensor, but doesn't rule out these other possibilities.
    A bad connection at the sensor
    An open in the ground circuit between the ECT sensor and the PCM
    i read that unplugging sensor makes fans come on for safety sake, sure sounds like ect or its circuit
    A short in the voltage feed between the sensor and the PCM
    A bad PCM (less likely)
    A bad temperature sensor (shorted internally)

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    Ditto, April 23, 2011, 12:36
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     Rookie

    Well while you ponder on that one, let's say it is the radiator being cooled down, could that mean the radiator is not allowing a proper flow of coolant? I appreciate your note, but Ive already read this on another site, I was hoping for a little more info based on My car's actual symptoms..Like I mentioned previously the ECT sensor has been changed and these codes appeared only after the radiator fan assembly was changed. I was wondering if all these issues are related to one another?

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    cogcan, April 25, 2011, 06:59
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     Journeyman

    as far as the overheating issue ,have you changed the thermostat, i dont see it mentioned,i assume its really overheating since u say it cools down on hywy ,also i dont believe the new fan has anything to do with the codes, i also dont suspect the pcm. p0118 means pcm reading too low a temp, but gauge is showing too hot-confusing! if u can check resistance of sensor cold -not running, should be around 2000-3000 ohms. start car and idle, should drop to around 200 gradually. u should erase all the codes to make sure u arent looking at history codes.

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