p0128 ect code?
 

good day all

I have a 2002 volvo s40 with only 50k miles and the code popped up at first I cleared the code and it didn't register again for another few weeks, seems like when the temperature drops around 20 degrees outside here in new York it affects the code never the less I replaced both the thermostat and ect sensor which where oem (lol 17 years old) with oem volvo parts

I only removed the upper hose to the tstat housing very little fluid spilled out I replaced both and started the car adding coolant till the middle of the reserve bottle.

I ran the car and drove for over an hour the code didn't clear itself the car never ran over 194 degrees and neither of the two fans came on?? I did bleed the system to the best I know how unless I missed a step I do have good hot air flow out of the vents ….is the radiator and cooling efficiency that great that I cant get the temperature over 195???? do is till clear the code and see if it returns I thought these codes reset themselves like my other cars ??? and yes I did remove the battery cables and the code was still there, seems like it was stored in memory so I am guess its supposed to be scanner erased ?

any suggestions TIA

good day, the better question is do I need to reset the code or does it clear by itself upon driving several times?

I have driven about 200 miles and still code hasn't cleared itself so I am assuming I need to reset via the scanner

I'm not sure about the code resetting itself, but it's certainly one I'd have no qualms about resetting manually (other than if I was due for an inspection, and worried that it would also set my readiness indicators in the process).

I don't think it's too unusual that the fans aren't coming on - they really only come on when the temperature is quite a bit higher, and the cool weather in the northeast could certainly keep that from happening (after all, our engines are very efficient).

I wouldn't worry about it too much as long as your temperature indicator needle is about where it should be (center on my V50), indicating that the coolant really IS coming up to a reasonable temperature. You almost certainly fixed the problem with the thermostat (and the sensor was probably a fairly low-$ "insurance item" to prevent a second trip to the shop, which I'd do all day long if I lived where you do! ;-)

Thanks! Habbyguy, well on the third day driving ,the CEL actually cleared itself, must of been one of those codes that after certain number of times turning the car on or miles driven it will clear the CEL car runs like a dream and still getting 27 miles to the gallon I was afraid of the temperature being too cool to keep running rich, still almost every part oem (17 years old but only 51k miles lol )

the CEL light may go out on some codes but the code itself is still stored. If you don't have a scanner (my $39 model from Harbor Freight does all the P codes ), just go over to Autozone and "rent" a scanner (its free at most stores) to clear the code. I doubt if it will return. You probably didn't get much air into the system (I never needed to burb the system after doing the ECT and when I did the upper radiator hose (its a good idea to keep one of those handy for the gen 1s, they tend to leak a the junction where the tube goes to the overflow tank) so I'm betting you are fine.