P0128 Tstat
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Junior Member
Joined: Aug 2013
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2004 CLK 55 Cabriolet
P0128 Tstat
So i've poked around and read a few threads about the P0128 code. I replaced the air hose and cleared the code a few days ago. It popped up again today so I guess the problem hasn't gone away. I'm fine with replacing the tstat but my car seems to be operating pretty reliably at around 80 degrees, sometimes a bit more, sometimes a bit less. Wouldn't it run cooler or hotter if the tstat were bad?
Like I said, i'm fine replacing the tstat but i'm kinda concerned that it's a wiring issue or something.
Thoughts?
Like I said, i'm fine replacing the tstat but i'm kinda concerned that it's a wiring issue or something.
Thoughts?
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From: Boston, MA
'14 ML350, '13 C220 CDI, '07 C280, '98 ML320
Thermostat could be sticking intermittently. Eventually it will be stuck, permanently.
Most of the times, these thermostats get stuck in open position. If it were to get stuck in closed position, engine will be in trouble very quickly.
If I were you, I'd buy a thermostat online and replace it at the earliest convenience.
Most of the times, these thermostats get stuck in open position. If it were to get stuck in closed position, engine will be in trouble very quickly.
If I were you, I'd buy a thermostat online and replace it at the earliest convenience.
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From: Llandudno, Cape Town, South Africa
late 2009 CLK 350 Coupe Elegance, '65 Jaguar S Type wires
80 degrees is too cold. That's why you are getting a 128. The standard thermostat starts opening at 87 deg C & is fully open at 90 deg C. That should be the operating temp.
Replace your stat.
Replace your stat.
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c230k
As pcy states the thermostat is probably sticking. My code come up last month but engine temp was sort of warm at first, and then after another week it was very low. I'd go ahead and replace it; it won't take more than an hour tops.
Thread Starter
Junior Member
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2004 CLK 55 Cabriolet
Thanks. I called the dealer and asked about price. He quoted me $58 plus a few more for rings. I told him i would just order it online and then he came down to $38 plus shipping. I still told him i'd order it online.
Is Wahler the tstat oem?
Is Wahler the tstat oem?
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Joined: Aug 2013
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From: Toronto, ON
2012 C300 Sport 4MATIC (current) 2006 C280 Elegance 4MATIC (sold)
I'm not getting any CEL or codes but in the cold weather (Below 0 Celsius) my engine temperature only goes up to about 75 or 80. Only in warmer weather will it go to the 85-87 mark. Should I replace mine? What about the temperature sensor? The coolant level is good and the coolant looks very clean.
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From: Austin, TX
2005 C230K(sold), Mk7 Jetta
I bought Wahler from Autohaus a year ago, it had two o-rings. One like a normal ring, and one ring with square profile. You may want to check parts dot com for the o-rings...
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2004 CLK 55 Cabriolet
I think you guys are right. I drove my car tonight probably 10 mins, let it sit for an hour or so, and then 10 mins home and it never got above 80 so I think you're right, the tstat is stuck at least partially open. Is it bad to drive for the next week or so until the new unit arrives?
Ps. It's probably in the high 20s-freezing here
Ps. It's probably in the high 20s-freezing here
Last edited by slimpee; Jan 14, 2014 at 11:17 PM.
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From: Raleigh, NC
2005 C230K, 2019 Honda CR-V, '74 Lotus Europa
I have the same problem. My car will eventually get up to 80 (which is just shy of 180F which is a reasonable temperature). Elsewhere Glyn advises babying your car till it gets good and warm - something I've been doing mostly because of my rather old habits to not stress a car till it's warm.
I have no doubt that it's important but I've wondered just why it's important now, though. It used to be because you needed to get the oil up to temperature so it would be a bit thinner and lubricate better but it seems that would be less important with oil that is 0 weight when cold. I wonder if it's to get to the heavier weight of the oil since 0w40 would act like 40 weight when it's hot. Maybe someone can clue us in on why it's still important.
In the meantime, I would follow Glyn's advice.
I have no doubt that it's important but I've wondered just why it's important now, though. It used to be because you needed to get the oil up to temperature so it would be a bit thinner and lubricate better but it seems that would be less important with oil that is 0 weight when cold. I wonder if it's to get to the heavier weight of the oil since 0w40 would act like 40 weight when it's hot. Maybe someone can clue us in on why it's still important.
In the meantime, I would follow Glyn's advice.
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From: Llandudno, Cape Town, South Africa
late 2009 CLK 350 Coupe Elegance, '65 Jaguar S Type wires
I have the same problem. My car will eventually get up to 80 (which is just shy of 180F which is a reasonable temperature). Elsewhere Glyn advises babying your car till it gets good and warm - something I've been doing mostly because of my rather old habits to not stress a car till it's warm.
I have no doubt that it's important but I've wondered just why it's important now, though. It used to be because you needed to get the oil up to temperature so it would be a bit thinner and lubricate better but it seems that would be less important with oil that is 0 weight when cold. I wonder if it's to get to the heavier weight of the oil since 0w40 would act like 40 weight when it's hot. Maybe someone can clue us in on why it's still important.
In the meantime, I would follow Glyn's advice.
I have no doubt that it's important but I've wondered just why it's important now, though. It used to be because you needed to get the oil up to temperature so it would be a bit thinner and lubricate better but it seems that would be less important with oil that is 0 weight when cold. I wonder if it's to get to the heavier weight of the oil since 0w40 would act like 40 weight when it's hot. Maybe someone can clue us in on why it's still important.
In the meantime, I would follow Glyn's advice.
The biggest reason to warm up a vehicle before making maximum power demands is to normalise all engine clearances & thus achieve proper hydrodynamic lubrication where appropriate.
Last edited by Glyn M Ruck; Jan 15, 2014 at 07:22 AM.
Senior Member
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From: Toronto, ON
2012 C300 Sport 4MATIC (current) 2006 C280 Elegance 4MATIC (sold)
Is the Wahler unit a fail safe type thermostat? I guess if I go ahead and change the thermostat I might as well change the coolant instead of reusing the old coolant.
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From: Austin, TX
2005 C230K(sold), Mk7 Jetta
AutohausAZ lists Wahler as OEM: http://www.autohausaz.com/search/pro...200@Thermostat
Super Moderator
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From: Llandudno, Cape Town, South Africa
late 2009 CLK 350 Coupe Elegance, '65 Jaguar S Type wires
I don't understand that. Even the "so called" winter thermostats were somewhere in the 90~93 deg C range.
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Joined: Jun 2008
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From: Llandudno, Cape Town, South Africa
late 2009 CLK 350 Coupe Elegance, '65 Jaguar S Type wires
Anybody here with a car that runs at 100 deg C?
Edit: Interestingly I note that conventional thermostats as fitted to M271 & M112 engines by Wahler are listed as 87 deg C stats. The Electronic thermostats as fitted to the M272/273 engines are listed as 100 deg C.
Edit: Interestingly I note that conventional thermostats as fitted to M271 & M112 engines by Wahler are listed as 87 deg C stats. The Electronic thermostats as fitted to the M272/273 engines are listed as 100 deg C.
Last edited by Glyn M Ruck; Jan 19, 2014 at 07:14 PM.
