Thermostat replacement - '02 E320
Thread Starter
Junior Member
Joined: Sep 2014
Posts: 33
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From: San Jose, CA
2002 E320 sedan, 1990 Mazda Miata
Thermostat replacement - '02 E320
Well, I may have my first opportunity to get my hands dirty after a month of owning our 2002 E320. While I was away working the SCCA Runoffs my wife took the car up to a wedding in Sacramento and the check engine light came on steady while she and her friend were coming home.
So I went out and bought an OBDII scan tool from Horrible Freight, plugged it in and it gave me the code P0128 - coolant thermostat. I have a good idea of where the thermostat is located; is it much of a hassle to replace (doesn't appear so to me)?
BTW, I did search first, and the whole first page of search hits were threads from a vendor.
Thanks in advance!
So I went out and bought an OBDII scan tool from Horrible Freight, plugged it in and it gave me the code P0128 - coolant thermostat. I have a good idea of where the thermostat is located; is it much of a hassle to replace (doesn't appear so to me)?
BTW, I did search first, and the whole first page of search hits were threads from a vendor.
Thanks in advance!
Thread Starter
Junior Member
Joined: Sep 2014
Posts: 33
Likes: 0
From: San Jose, CA
2002 E320 sedan, 1990 Mazda Miata
I was all set to change the 'stat...
I bought myself a set of external Torx sockets (which is fine; I understand I may need them for future jobs) and a Wahler thermostat assembly from Pelican Parts which came in yesterday. So this morning I had planned to put in the new thermostat; figured I had time because the wife needs the car around ten this morning.
I walked out to the garage, started the car so I could move it out of the driveway and put it up on ramps... and the CEL is no longer on! Given that the code I mentioned in my original post is the only one it returned, anyone have an idea why? In my experience, there's no such thing as an intermittent thermostat problem...
I walked out to the garage, started the car so I could move it out of the driveway and put it up on ramps... and the CEL is no longer on! Given that the code I mentioned in my original post is the only one it returned, anyone have an idea why? In my experience, there's no such thing as an intermittent thermostat problem...
MBWorld Fanatic!
Joined: Jan 2004
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From: Seattle WA
99 E320
trouble codes are not exact. they may be delayed and an inventory temporarily
cached in memory to prevent false positives. they also (re)interrogate the
sensors to see if previously stored 'hits' still exist. they check and double check
so may sometimes reset. some codes must be manually reset by someone with
advance diagnostic equipment. CEL codes tend to be at the lower end, low
stress, low alert category (in my opinion) which can automatically reset
cached in memory to prevent false positives. they also (re)interrogate the
sensors to see if previously stored 'hits' still exist. they check and double check
so may sometimes reset. some codes must be manually reset by someone with
advance diagnostic equipment. CEL codes tend to be at the lower end, low
stress, low alert category (in my opinion) which can automatically reset
Last edited by raymond g-; Oct 17, 2014 at 11:06 PM.
Thread Starter
Junior Member
Joined: Sep 2014
Posts: 33
Likes: 0
From: San Jose, CA
2002 E320 sedan, 1990 Mazda Miata
Last night the CEL came on again. I pulled codes this morning and it came up the same as my previous test. Guess I need that new thermostat after all!
I will also replace the radiator hoses, as I noticed the upper feels pretty soft.
I will also replace the radiator hoses, as I noticed the upper feels pretty soft.
