Help on PO128

[vmaganti]

Hi,
Last week my 2000 s40 got Check engine light and when I verified at local autozone center, they told it was PO128, faulty Engine coolant tempurature sensor.
I took it to the dealer and they told $500 for replacing Engine coolant temporature sensor and Thermostat.

I want to find out if anyone had experince on it and if it can be a DIY or not

Thanks,
Veera

[MadeInJapan]

It is not that hard...either you can do it if you're mechanically inclined or have an independant mechanic do it for much cheaper. It is best to go ahead and replace the thermostat with the 87degree one rather than the higher temperature rated one (especially with winter coming on, and also if you live in a cold region). www.fcpgroton.com sells both but I noticed that the temp sensor (Engine Coolant Sensor or ECT Sensor) is not listed on their site so you'll have to call them, if you're wanting to buy the parts yourself for a savings.

[USN89]

Veera,

First of, I hope your P0128 problem has been resolved.

I have encountered the same code 3 weeks ago right after changing transmission fluid in my 01 S40. My code book states temperature sensor senses low temperature and it does not specify which temp sensor (engine or tranny).

Thinking of the obvious, I went back to my garage and checked the tranny fluid level. It looked like I overfilled it just a bit. I drained about 1/4 quart of fluid, erased the code, and it did not show up again. I suppose the extra fluid kept the temperature too low for the sensor's operating temp.

If this isn't it, I think Made In Japan is right on track in your case.

NOTE ON DRAINING SMALL AMOUNT OF FLUID:

Do not remove the drain plug completely otherwise you won't be able to control the flow; you'd either end up having a deluge or worse, get burned by hot fluid. Just loosen it slowly until you see a drop forming. Then, tilt the now loose plug away from the pan with a slight finger pressure and you would be able to control a tiny flow of the pink stuff.

I hope this helps anyone.