Outside Temp Display is wrong temp - PeachParts Mercedes-Benz Forum

GregMN · #1 11-18-2009, 12:30 PM

1991 350SDL

A week ago the outside temp display seemed to be accurate. Now the displayed temp is about 20 to 30 degrees F too high. The sensor is mounted behind the license plate and has not moved itself to a warmer location for the winter.

Has anyone else experienced an inaccurate temp reading and figured out what the problem was?

Thanks,
Greg

F18 · #2 11-18-2009, 02:34 PM

Quote:

Originally Posted by GregMN

1991 350SDL

A week ago the outside temp display seemed to be accurate. Now the displayed temp is about 20 to 30 degrees F too high. The sensor is mounted behind the license plate and has not moved itself to a warmer location for the winter.

Has anyone else experienced an inaccurate temp reading and figured out what the problem was?

Thanks,
Greg

Greg.... that is an odd one! I have seen the temp displays sometimes reset to Centigrade which would show lower digits than the normal Farenheit temp scale. Usually that occurs when someone hits and holds the wrong botton or a battery is disconnected for a while.
Most of those temp sensors just quit working when defective.
Are you looking at it after the engine is parked and idelling for a while?....which would be influenced by rising engine temps. Does it settle back to normal while driving?

Graplr · #3 11-18-2009, 02:41 PM

Did you block your grill recently? I noticed a bit of a change when I did that.

How long have you noticed this change and how much has the car been driven during this time?

GregMN · #4 11-18-2009, 03:46 PM

I notice it driving at speed were it was accurate before.
No modifications have been done to the car in the last 2 weeks.
No battery disconnects or dead battery.

Biodiesel300TD · #5 11-18-2009, 04:09 PM

Its the WVO it has broken the sensor!

I'd look at the wire coming from the probe. It could have gotten frayed or cut. Does the temp go up and down or does it read a constant number all the time?

BigBen · #6 11-18-2009, 11:15 PM

Quote:

Originally Posted by GregMN

1991 350SDL

A week ago the outside temp display seemed to be accurate. Now the displayed temp is about 20 to 30 degrees F too high. The sensor is mounted behind the license plate and has not moved itself to a warmer location for the winter.

Has anyone else experienced an inaccurate temp reading and figured out what the problem was?

Thanks,
Greg

My 1992 300D has the exact same problem.

I have a more important problem with a likely bad injector to worry about. If it's just an injector, then I'll have a look at this issue. Let me know if you find something.

I looked at the price of a new probe and found it didn't make sense (+100$) I think...

Bye,

i-osprey · #7 11-19-2009, 12:50 AM

My '93 300D reads exactly 17F low.

It is perfectly consistent at all temperature ranges but it reads 17F low.

I looked into replacing it too but the $100 was too much for my blood too.

GregMN · #8 01-08-2010, 06:22 PM

I had occasion to remove the gauge cluster. After I re-installed it, the outside temp gauge seems to be reading correctly now. Must be a microsoft thing, unplug it for a while, plug it back in and turn it on and now it works.

compress ignite · #9 01-08-2010, 07:26 PM

"Somewhere" here I read a how to by "Somebody" on the use of a generic temp
sensor (AT Greatly reduced cost).If/When I locate it I'll post.

ErrrrgrrK ! Here Ya Go !

"barrie is offline
Registered User

Join Date: Jan 2000
Location: buckhorn, ontario, Canada
Posts: 101
Sensor Replacement
Ron,

What you get from the dealer is a sensor soldered to one end of a 2-conductor wire. This enables you to replace the sensor cable to the display connector (around the fuse box). Because of the labor involved in routing the cable through the engine wire bundle, many mechanics will just cut-off a piece and splice it to the old cable (not recommended!). Others, to avoid the splice, will desolder the sensor from the new cable and replace the old sensor.

In any event, all you need is the sensor itself which is an NTC thermistor. Units such as the Fenwal #192-302LET-A01 or Thermometrics #EC95F302W are more durable and accurate than the original spec. The Thermometrics unit, for example, lists for $3.75 and is available from electronics suppliers such as Newark and Allied.

Hope this helps.

[Edited by barrie on 02-27-2001 at 04:04 PM]
Reply With Quote"

Damn, You really can find ANYTHING with "Froogle" and Amazon...

http://www.newark.com/jsp/search/productdetail.jsp?SKU=52F3338&CMP=AFC-GB100000001

http://www.google.com/products?q=+Fenwal+%23192-302LET-A01&aq=f