Hi All,
Just bought my 1st Benz (1999 E300DT). Before I bought it the AC was not working, previous owner took it to have it looked at and mech said it just needed the system reset and that it was probably due to car sitting / low battery. Well AC works fine, but I decided to have a look at the error codes.
Here is what I got:
Sensor
1 - 80
2 - 78
3 - 44 Left Heater Core Temp
4 - 40 Right Heater Core Temp
5 - 32
6 - 159
7 - 15
8 - 114

Errors
B1128 Heater core temperature (B10/1)
B1229 Heater core temperature (B10/1)

From EclassBenz AC diag

• Your A/C system is working properly. The evaporator temperature is 32 degrees.
• If your problem is air flow, rather than air temperature, it's likely that your blower regulator went bad.
• Code B1228 Explanation: This sensor measures the temperature in the left side heater core. It is reporting an implausible temperature or voltage reading.
• Code B1229 Explanation: This sensor measures the temperature in the right side heater core. It is reporting an implausible temperature or voltage reading.

Near as I can tell everything works; AC, heat, blower, defrost, etc. I have searched a bunch of forums and can find nothing on the heater core temp sensors.
Is this even an issue? In my looking around B10/1 is also called Duo-temp sensor and I believe is located behind the radio (or there abouts!).

What car are we talkin about? Those who can help will need to know...

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'85 300D, 'Lance',250k, ... winter beater (100k on franken-Frybrid 3 Valve Kit)
'82 300D, 'Tex', 228k body / 170k engine ... summer car
'83 300TD Cali Wagon 210k, wife's car

Sorry did not set up my signature yet!
1999 E300DT

Doesnt look bad to me although I would defer to Matt L who is much better with AC.

If it were mine i'd erase the codes and check it again in a few hours.

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Terry Allison
N. Calif. & Boca Chica, Panama

09' E320 Bluetec 77k (USA)
09' Hyundai Santa Fe Diesel 48k (S.A.)

Thanks Terry,
I will try that and report back.
The thing that makes me think I have a problem is I that the only way I get heat is by turning on front defrost. AC seems fine.

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Mike

Current 2015 GLK 350 16k miles

Past 1999 E300DT 330k

Finally getting back to this issue.
I have reset the codes (a couple of times) and these 2 errors always come back.
The sensor is cheap and looks pretty easy to replace so I may try swaptronics to fix.

Any feedback would be greatly appreciated!

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Mike

Current 2015 GLK 350 16k miles

Past 1999 E300DT 330k