CorAegean

Thermostat question if anyone can help: 2009 SL550 CEL is on. Code is p0128 "thermostat stuck open." But here's a pic of my temp-gauge showing temp right about where it should be, and my heater warms up fine. Is there possibly a problem with the sensor? Or, does the thermostat "stick" and then re-close? (CEL HAS gone out & then back on) If so, is there any coolant system recommended "treatment" that can condition the system to free up sticky parts?
I'm trying to avoid replacement if possible. If I do have to replace, does anyone know of a good tutorial specific to r230 they can point me to? Indy shop wants $625+tax...big NTY. Can get one online as low as $29!

Thanks much for any advice.
Reid C
Collierville/Memphis TN

Gene Fiorot

Find a new Mechanic Quickly. And for the diy guy it is an easy repair.

CorAegean

Anybody out there know a good indy/labor only in the Memphis, TN area? Have lost contact with my old guy.