Artbuc

My niece just called and said her Check Emissions light came on. She also got a message to check her gas cap which she did but light is still on. Car seems to be running fine.

I am not familiar with this feature. Can you access diagnostic codes just like you do when you get a Check Engine light?

Any ideas about what typically causes the Check Emissions light to come on? Thanks.

kipsy

its usually the gas cap or some temperatire sensor under the hood.

Artbuc

Update: I was mistaken about the gas cap message. She only got the "Check Emissions System" message. The only code detected is P0128 with no other codes pending.

Since we have no other ECT related codes, is it a fair assumption that we need a new thermostat? Thanks.

kipsy

check the coolant reservoir and fill to the proper line (hot or cold) with honda coolant and go for a drive of 30 minutes, seems to help - see the link

http://www.acura-tsx.com/forums/showthread.php?t=717835

Artbuc

Coolant level is fine - was the first thing we checked.

DuckDodgers

P0128 "Cooling System Malfunction"

Need to check coolant level and this one is likely a Honda/Acura Specialist or Stealership issue if nothing is obviously wrong. The code is too general and covers too many things...however you should confirm the radiator fan is working at some point.

Otherwise, it's likely a sensor issue.

ALPH4

p0128 = coolant temperature is below the thermostat regulating temperature

DuckDodgers

ALPH4, actually, P0128 is "Cooling System Malfuntion" on '06-'08, US model TSX's. Got that straight from the Service Manual. Your explaination sounds like a generic reader code...and note that Acura is concerned with an overtemperature possibility on code P0128 because of the check of the radiator fan.

Artbuc

Everything checked out ok. Thermostat started to open around 170 and was fully open at 190. ECT2 turned on the fans at 215 (measured at top of radiator so actual temp at ECT2 was probably 10 degrees or so cooler). Access to both ECT's was too tight for me to ohm them but pins were clean with no sign of corrosion. CE light has stayed off for 5 drive cycles. Since I don't have a scanner, I don't know what the PCM thinks the engine temp is but the dash gage is where it always has been.

DuckDodgers

Sounds like a sensor issue is most likely, but with everything looking OK, I just don't know.

Artbuc

Yep. My guess is that the thermostat may be opening a tad too soon and the ECT may be indicating on the low side of range. Acting together, the PCM concluded that it took too long to warm-up. I assume the PCM has to see this condition 3 times before the CE light comes on so something isn't right and hopefully it isn't the PCM.

DuckDodgers

Standard Thermostat:

Lift height: Above 8.0 mm (0.31 in.)

Starts opening: 169-176F (76-80C)

Fully open: 194F (90C)


Looks like the thermostat is fine...

The real problem is that one of the key checks is clearing the P0128 and looking for a new code to check if everything seems OK (as it seems with you). Unfortunately, it gives no hint what those codes are.

The easiest (relatively) check now is substitute of a known good ECM/PCM...but that prohibitively expensive outside the dealership.

Artbuc

To clarify, I did not remove the thermostat and check it in a pan of hot water. I estimated the opening temp by observing coolant movement in the radiator, feeling the temperature of the top radiator hose and measuring the coolant temp in the top of the radiator. I also had a thermocouple attached to the engine block at ECT which read about 9 degrees cooler than actual. I did not bother attaching a thermocouple to the thermostat housing as it is plastic and would have had too much conduction loss. So, it is possible that the thermostat opened at 10-15 degrees sooner than I think.

PS I would not go to the trouble of removing the thermostat without installing a new one, even if the old one checked-out ok.