Trying to clear a "Check Engine" situation.

Most recent state inspection revealed a discrepancy between the coolant temp and the OEM thermostat spec (192 F I believe). I have learned from this forum that the code was most likely P0128 - I didn't ask. Anyway they cleared it for me and I was not overly concerned. However, my wife, who drives this car on a daily basis is starting to drive me nuts - she hates those little lights.

The expansion tank took a bit of coolant - maybe a quart to a quart and a half. Have a new t-stat in hand, but am waiting to see if packing the system with coolant will clear the permissive.

Currently have the battery disconnected and am wondering if waiting an hour or two before re-energizing will clear the warning (if that was the problem).

If that amount of time is normally sufficient to reset the computer and the light still appears, I will change the t-stat next. And then it's on to checking the connections to the sensor and then R&R the sensor.

Next: vacuum leaks in the emissions system.

When I removed the gas cap (which appeared to be nice and tight) I did not hear that tell-tale hiss that indicates an in-rush of air. Should I have heard that sound?

Jerry

Post moved. Member notified.

Change the thermostat you should be fine. Get a good one from volvo not aftermarket junk from the local parts store.