P0128 code thermostat reading
02-06-2015, 12:04 AM
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01 ML55 / 97 E320/01 CLK55/ 2010 S550
P0128 code thermostat reading
Just recently on my 2010 S550 the check engine light came up and I pulled the code P0128 and I've read it is mostly from a bad thermostat or the built in non replaceable sensor. Dumb design, they should've had the sensor threaded to replace. Now your forced to buy the whole damn housing and all. Now it seems my operating temperature is working fine, heating works fine and all. I think the sensor is defective. Now I've tried searching but did not find. Anyone knows what the sensor on the thermostat housing should be reading? I wanted to meter it. Perhaps anyone who is willing to meter their working one can chime on this. I cannot find any info on this. I will call the dealer for this info but I feel they won't give me an answer and I'd be forced to buy a new setup. Another thing that failed recently on my car is the bottom seat heater. Back works but bottom not.
02-11-2015, 04:24 PM
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I just got my thermostat replaced by a shop I thought would be able to at least replace a thermostat on a car. Replaced the unit, check engine light (P0128) gone, and now I have the joys os a squicky belt sound in addition to wierd humming coming from my steering pump. Replaced steering pump fluid, no change. Same sound,
03-03-2015, 10:08 PM
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01 ML55 / 97 E320/01 CLK55/ 2010 S550
In case you want to know the procedure to replace the unit yourself:
It's relatively easy. Can be done in an hour. If my memory serves me right, I paid around $130 for it. First you need to drain the coolant from the lower corner of the radiator (driverside) by twisting the valve open, remove the serpentine belt by using a socket wrench to release the tension from the belt, then remove the pulley in front of the thermostat, remove the sensor plug, and then use an 8mm. box end wrench (gear wrench type) and remove the two torx bolts. The housing will pull out and then remove the clip that holds the hose stationary. Reverse the procedure, very easy.
Bob
It's relatively easy. Can be done in an hour. If my memory serves me right, I paid around $130 for it. First you need to drain the coolant from the lower corner of the radiator (driverside) by twisting the valve open, remove the serpentine belt by using a socket wrench to release the tension from the belt, then remove the pulley in front of the thermostat, remove the sensor plug, and then use an 8mm. box end wrench (gear wrench type) and remove the two torx bolts. The housing will pull out and then remove the clip that holds the hose stationary. Reverse the procedure, very easy.
Bob
