Aftermarket Coolant Temperature Sensor?

Has anyone used one and passed emissions testing? I think the OEM one
on my 91 Civic has finally bit the dust and is why my car is failing
emissions and has slightly reduced mileage lately. Autozone has the A/
M ones for $23.

This comes after quite a lot of diagnosis effort. Today I think I had
the proverbial breakthrough: The purge cut-off solenoid valve (in the
evaporative emissions control system) was stuck in atmosphere vent
mode, whereas once the rad fan has come on once, it is supposed to
send a vacuum signal to the charcoal canister's diaphragm. I found the
electric signal to the solenoid valve was constant at battery voltage,
which tells me the ECM is not varying its signal to the valve, which
implicates AFAIC the danged TW sensor. With J Beam's observations on
the TW sensor of a few months ago, and slightly reduced mileage of
late, and some other things (like the importance of doing emissions
testing in warmer weather on these old Hondas and how much control the
TW sensor has in open loop operation) it all seems to add up.

 

why aftermarket? oem are ~$26. it's in the "engine sub cord clamp"
section of majestic and bk's listings.

 

In a rush to pass emissions. Plus add $5-$10 for s/h when using the
online OEM parts sites. Gonna see if the junkyard has any newer used
OEM ones today.

 

in my experience here in the bay area, the honda kids that surf junkyards
clean those out quickly - only the old stuff is left. i'd buy new and
save yourself the gas - unless you have other reasons to go.

good diagnostics btw - good for the archive.



tegger, istr that you'd had oil getting dirty quickly. as a data point,
part of the reason i got alerted to this tw sensor problem was because i
have two identical engines in a civic and crx. one was exhibiting
problems, the other not. among the differences was that the civic, the
one with the problem, was showing much more carbon load in the oil much
more quickly. makes sense if you consider what results with the fuel
mixture if the temperature is "too low".

 

I sold the car yesterday (see other post today), per my goal of a few
weeks. But I continue to suspect the ECT sensor may be a cause of the
idle emissions problems. Before the sale, I put a shiny looking ECT
sensor in from I think it was a 97 junkyard Civic (same ECT sensor,
per bkhondaparts.com) and got no improvement. However, I am not ruling
out that a brand new one would have improved things. Maybe the ECT
sensor has a short life. In my massive effort to fix the emissions
problem quickly, I saw other sites that backed up your contention
about ECT sensors.

IOW, I think the ECT sensor is a ripe item to replace when one fails
emissions and or maybe every 10 years/150k miles.

(How many other car makes have a maintenance schedule with 10-year/
150k miles items?)