New to me low mileage E430 has the EC light coming on after 15-20 minutes driving. Until the light comes on, AC seems to work fine. Checked codes and see a B1226 as only fault. Resetting buys me another 15-20 minutes of AC. My question is: I see both an in-car temperature sensor that looks like a small cylinder with a plug on one end and a metal point on the other (URO Parts Cabin Air Temperature Sensor | 2108300072) and a Mercedes branded part that is a small box with a fan and pins for a plug (Mercedes Interior Temperature Sensor - Genuine Mercedes 1408300008). Can someone tell me which is correct part to replace the "in-car temperature sensor". I've seen the fan described as both the sensor fan and the temperature sensor itself. Is the URO part above something that goes inside of the "fan box" or a completely different part? Thanks for your help.

 

I think you're going too fast chasing after the wrong item.
The fanned temp-sensors don't fail that fast !
passenger footwell sensor gets easily damaged...

Can you troubleshoot the AAC Module ?
See what climate data are reported vs. failed.
Solution may become clear.

 

Ok, so there is more than one in-car temp sensor? I'll pull the values from the climate control unit and see what that says. Since I only had one code - B1226, I thought it would be the in-car temp sensor... but if there are two of them, I'll keep going. Thanks

 

yes, keep going... this is a Mercedes: you've got half dozen A/C temp sensors.
What are that DTC specifics ?

 

You need the Mercedes part with the fan (#1408300008). That whole unit is the sensor. The fan pulls cabin air across the actual sensor inside the box. The little URO cylinder is a different part. Your fault code is for the sensor that the fan unit reads. Replace the fan assembly and your problem should be fixed.