Ok guys - here's the scenario. I have an '03 AP1 w/ 26k on the odometer, located in Central Florida (hot).

I noticed about a month ago that my coolant temp gauge went from 3 bars to 2, and then back to 3, even after car was at full operating temp. I figured it may have been a fluke, since it didn't happen again for a week or so.

A couple weeks go by, and temp gauge does the same thing, except this time it cycled from 3 bars to 2 a few times.

Another week goes by and she's starting to do the 3 bars to 2 cycle more often, almost about every time I drive. I starting thinking that maybe the S2000's just run a little cooler depending on weather as the Florida temps have been coming down some. Well, today on the way to work the CEL comes on (full steady, no blink).

I get home, search on the boards, figure out how to the DIY DTC test. CEL shows code 8-7 on the blink test. Search again and find out it's CEL Code P0128 - Coolant Temp Below Thermostat Regulating Temp.

My question is given the scenario, is it likely it's just a radiator cap issue, or being that the symptoms have gotten worse over the past month time frame, it's probably an intermittent thermostat that was getting worse over time and now finally just stuck open.

The auto parts stores are closed in my city and I'm just trying to get my ducks in a row before I run to the store tomorrow. Also, I assume as long as I stay out of Vtec, there really shouldn't be any real danger of driving her to and from work (about 14 miles round trip) until the weekend when I can put her on jackstands and start wrenching on her.

Any advice is much appreciated.

Thanks in advance!

 

I usually take it into the honda dealership garage and ask them if they know whats wrong......then they tell you "what it could be", then they say "we could take it back" which they will charge you 89.50 to look at it. Thats when i say thanks for the info and get out.

 

I have a hard enough time letting someone valet my car, nonetheless letting some stealership take it behind into their garage and touch it with their grubby little hands - regardless if I have to pay for it or not.

I'm not losing any coolant either, radiator is still filled to the rim.

 

I have seen this be a bad temp sensor. Fairly cheap and not that hard to replace either.